Web Application Security Testing Guide | Secure Web Apps

Think ofyourweb app as the front doorto your digital business. Your
app is always “live,” processing logins, transactions, and private
information – and this is all done in an online environment. Attackers
are lurking nearby, waiting for a vulnerabilityto slip in through.
Securitythreats are not slowing down. In fact, they become smarter,
faster, and more complex with every newfeature. As teams rush to
deliver updates and enhancements, security can sometimes be
neglected. The truth is, users expect security, even ifthey never ask
for it.
This blog is going to discuss web application securitytesting in depth.
You will get a real-life explanation ofwhytesting is important, how
common vulnerabilities like SQL injection and cross-site scripting
work, and what can happen when they are not tested for. We will also
SECURITYTESTING TESTAUTOMATION
WebApplicationSecurityTesting:The
UltimateGuidetoProtectingWebApps
•
BY QATEAM

compare manual testing with automated testing, identifywho does
what, and howto build security into your development process from
the beginning. Ifyou have any role from coding, testing to leading a
product team, you will leave with the knowledge and tools needed to
ensure your app is secure, safe, and reliable. Let’s go!
Table ofContent
Introduction to Web App Security
WhyWeb Application Security is Not Only For Geeks
The Real-World Cost of Getting It Wrong
Security Is a Moving Target
The Chain Is Only as Strong as Its Weakest Link
WhyWeb Application SecurityTesting Matters ?
The Dark Side of Code
What IfYou Don’t Test Security?
What Does SecurityTesting Actually Involve?
SecurityTesting Is a Habit, Not an Occasional Exercise
A Close Call: The Importance of RegularTesting
Common attack types (XSS, SQLi, CSRF)
1. Cross-Site Scripting (XSS): When Websites Turn
Against You
How it works?
Real-World Example
2. SQL Injection (SQLi): Hacking the Database
How it works?
Real-World Example
3. Cross-Site Request Forgery (CSRF): Fooling Users into
Acting
How it works?
Real-World Example
Who Performs Web Application SecurityTesting
Internal SecurityTeams

QA Engineers with Security Knowledge
Ethical Hackers and Penetration Testers
Third-Party Security Firms
Bug Bounty Hunters
HowWeb App SecurityTesting is being Performed ?
SecurityTesting Types
Manual Testing
Business Logic Testing
Authentication and Authorization Testing
Penetration Testing
Automation Testing
Security Scanners (e.g., ZAP, Burp Suite)
Static Application SecurityTesting (SAST)
Dynamic Application SecurityTesting (DAST)
Interactive Application SecurityTesting (IAST)
Software Composition Analysis (SCA)
Secret Scanning
Testing Approaches
Black Box Testing
White Box Testing
Grey Box Testing
Common Web Application Vulnerabilities
1. Injection Attacks
SQL, Command, and LDAP Injection
Code Injection
XML Injection
2. Cross-Site Scripting (XSS)
Stored, Reflected, DOM-based
Server-Side XSS
Client-Side Framework XSS
3. Cross-Site Request Forgery (CSRF)
How it Works and Prevention
Token Misuse
API-Specific CSRF
4. Broken Access Control

Privilege Escalation Issues
Insecure Direct Object References (IDOR)
Missing Function-Level Access Control
5. Security Misconfigurations
Unpatched Systems, Exposed Headers
Default Configurations
Misconfigured Cloud Services
6. Insecure Deserialization
Remote Code Execution Risks
Data Tampering
Denial of Service (DoS) via Deserialization
Reporting and Remediation: Turning Security Findings into
Action
1. Writing Effective Security Reports
Structure, Clarity, and Impact
Prioritizing Findings
Communicating to Stakeholders
2. Risk Rating and CVSS
Severity Metrics
Qualitative vs. Quantitative Ratings
Temporal and Environmental Factors
3. Collaboration with Developers
Fixing and Validating Vulnerabilities
Building a Security Culture
Handling Resistance
4. Retesting After Fixes
Ensuring Vulnerabilities Are Resolved
Regression Testing
Automated vs. Manual Retesting
5. Monitor & Maintain Security
Continuous Monitoring
Patch Management
SecurityAwareness Training
Best Practices: Incorporating Security into YourWeb

Applications
1. Adopt a Shift-Left Security Mindset
2. Adhere to Secure Coding Practices
3. Enact Strong Authentication and Authorization
4. Secure APIs and Third-Party Integrations
5. Perform Periodic Audits and Updates
6. Conduct Threat Modeling
7. Defend Against Common Vulnerabilities
8. Encrypt Data at Rest and in Transit
9. Test and Monitor Periodically
SecurityTesting Standards & Guidelines: A Simple Guide to
Keeping YourApp Safe
1. OWASPTop 10
Frequent Vulnerabilities and Resolutions
Prioritizing OWASP Risks
Training Teams on OWASP
2. NIST Guidelines
Testing Procedures and Controls
Risk Assessment Processes
Incident Response Planning
3. CWE/SANS Top 25
Most Dangerous Software Errors
Static Analysis for CWE
Error Handling Best Practices
4. PCI-DSS forWeb Security
Security Checklist for Payment Apps
Vulnerability Management
Third-PartyVendor Security
5. ISO 27001 for Security Management
Conclusion
Introduction to WebApp Security
Ifyou have ever done some shopping online, accessed your bank

balance via your phone, or simply looked at social media, then you
have used the applications ofthe web. Such applications are now an
integral part of everyday life that we do not even give it much
thought. Yet, behind each problem-free log in and trouble-free
transaction, there lies an invisible realm of securitythreats, and an
army of individuals who labortirelesslyto keep your data secure.
WhyWebApplication Securityis Not
OnlyForGeeks
Web application security is not just an IT buzzword. It is an issue for
everyone, right from the CEO all the way down to the end user. In
essence, web app security is about ensuring that data that you post
online or offline, whether it is your e-mail address, your credit card, or
your health record remains personal and safe.
Let’s phrase it differently: suppose you are in charge of a small
bakery, and you just introduced an online ordering platform. You
would not want somebodyto break into your kitchen and mess with
your recipes, right? The same goes foryourwebsite. Ifyou do not
secure the virtual doors, someone may break in and create mayhem.
The Real-World Cost ofGetting It Wrong
The prime example ofthings that can go terriblywrong is TalkTalk’s UK
breach.
In 2015, hackers found a flaw in an old part ofTalkTalk’s website. With
it, they accessed the personal details of over 150,000 customers
names, addresses, bank details. The aftermath: TalkTalk lost millions
of pounds, incurred regulatory sanctions, and had its reputation
plummet. All because of one, neglected vulnerability.

SecurityIs a MovingTarget
Here’s the reality: the dangers to web applications are not static.
There are always newtricks being concocted by hackers, and the
technology landscape keeps evolving. What was secure five years ago
would have holes in it today. So, web application security is not a
project that we do once and are done with it. It’s an ongoing effort.
And it’s not all about the technical mistakes, either. Human errors like
“password123” or simply neglecting to install patches can let
attackers in just as quickly as an application flaw.
The Chain Is Onlyas Strong as Its
Weakest Link
It’s possible, even common, forthe weakest link to lie somewhere
otherthan in your own application.
Considerthe BritishAirways incident back in 2018. Attackers didn’t
compromise the airline’s corporate website. Instead, theytargeted an
exploit in an outside script deployed on the checkout page. That small
crack was all they required to steal customer payment data from
hundreds ofthousands oftransactions.
The moral ofthe story? Web application security is about examining
the complete environment, not just your own domain.
WhyWebApplication SecurityTesting
Matters ?
Let’s suppose you just constructed an exquisite new home. Would
you move in before checking the door and window locks? Most likely
not. The reasoning is the same when it comes to web applications.

Before inviting users in, you must ensure everything is secure.
The Dark Side ofCode
Each web application is composed ofthousands, sometimes millions
of lines of code. Even professional developers are prone to errors, and
attackers specialize in uncovering those small mistakes. That’s where
securitytesting takes over. It’s akin to seeking the services of an
expert to examine your home, searching for anyvulnerabilitythat an
intruder can use.
What IfYou Don’tTest Security?
Missing out on securitytesting is similarto walking outside to your car
in a public parking lot with the doors unlocked. Eventually, someone is
going to open the door. The ramifications can be dire:
Data Breaches: Sensitive data can fall into the wrong hands.
Financial Loss: Financial losses may occur directlyfrom theft, or
indirectlythrough lost business and fines. Companies have an
obligation to secure customer data, and failing to do so may lead
to lawsuits and financial penalties.
Reputation Loss: When word spreads that yourwebsite is
unsafe, the customers are unlikelyto want to go back.
A classic example is the TalkTalk hack discussed above. TalkTalk could
have picked up the vulnerabilitywith just a few security checks.
Instead, they paid the cost.
What Does SecurityTestingActually
Involve?
Securitytesting is not about firing out a high-end tool and walking
away. It’s an even balance of automated scans and manual

investigation. This is what it commonly encompasses:
Map OuttheApplication: Tracking down where users can
connect with yourwebsite.
Permissions Checking: Ensuring that users cannot get to
things they shouldn’t.
Attemptingto BreakIn: Ethical hackers, also referred to as
“pen testers,” attempt to take advantage ofweaknesses, similar
to attackers.
Validating Inputs: Preventing anything users can type in, such
as searches or comments from being exploited to inject harmful
code.
ReviewingAuthentication: Ensuring that logon systems are
secure and sessions cannot be hijacked.
SecurityTesting Is a Habit, Not an
Occasional Exercise
It’s all too easyto assume you can just test it once and forget. But
each time you add an update, newfeature, or new infrastructure, new
vulnerabilities can emerge. That’s whythe best teams embed security
testing as part oftheir routine, part oftheirworkflow, and not an
afterthought.
AClose Call:The Importance ofRegular
Testing
One popular online store recentlyfound an open API endpoint that
they didn’t realize existed because of an update. Had attackers
discovered it, theywould have exposed customer orders and personal
information. Thankfully, because theywere performing automated
security checks that they do regularly, they caught the problem
before it ever manifested. That’s the value of proactive testing.

Common attacktypes (XSS, SQLi, CSRF)
1. Cross-Site Scripting (XSS): When
WebsitesTurnAgainstYou
An attacker learns to place malicious scripts on pages that other
users visit. These scripts typically execute within the victim’s browser,
and the attacker can use them to steal cookies, hijack sessions, or
deface the site.
Howitworks?
1. The website does not adequately sanitize user input.
2. An attacker makes a post or message with an embedded script.
3. The script automatically runs when another uservisits the page.
Real-World Example
The British Airways hack compromise involved attackers inserting
malicious data into an external script. When each customerwould
input theirfinancial information, the script would secretlytransmit
that data to the hackers. It’s an all-too-familiar display of XSS.
2. SQLInjection (SQLi): Hacking the
Database
SQL injection is an oldie but goodie in the hacker’s playbook. It occurs
when an attacker places specially created input into the form field,
which makes the application execute unknown commands against
the database.
Howitworks?

1. The login form does not verify anything that users input.
2. An attacker inputs SQL code where the username or password
would go.
3. The database runs the code, revealing or changing sensitive
information.
Real-World Example
The TalkTalkhack occurred as a consequence of SQL injection.
Hackers utilized it to gain entry into customer data, simply because
the application failed to validate input.
3. Cross-Site Request Forgery(CSRF):
Fooling Users intoActing
CSRF is more insidious. It convinces users to do things they didn’t
mean to, such as resetting their password or sending money, just by
visiting an evil website while still logged into another service.
Howitworks?
1. The victim is already signed in to a website (e.g., their bank).
2. The attackerforwards them with a link or embeds an invisible
request in an email orwebpage.
3. Unbeknownst to the victim, the victim’s browser makes an
automated request to the bank, conducting an act as though
done bythe victim.
Real-World Example
Suppose that a customer is logged into their bank account. He
browses an untrustworthywebsite, which quietly posts a form to
initiate an orderfortransferring money out oftheir account. Ifthe
bank’s website does not verifythe source where the request is

initiated, the money is transferred without asking questions.
Who Performs WebApplication Security
Testing
Web application securitytesting is a collaborative effort that involves
a variety of specialized roles. Each group brings unique skills,
perspectives, and tools to the table, ensuring comprehensive
coverage against a wide spectrum ofthreats. Here’s a breakdown of
the key players involved in web application securitytesting:
Internal SecurityTeams
Internal securityteams are dedicated professionals working within an
organization. Their deep understanding ofthe company’s
infrastructure, applications, and business processes allows them to
identifyvulnerabilities that are specific to the organization’s
environment. These teams often:
Develop and implement security policies and procedures.
Conduct regularvulnerability assessments and penetration
tests.
Respond quicklyto incidents and emerging threats.
Collaborate closelywith development and ITteams to remediate
issues.
Having an internal team ensures ongoing vigilance and a proactive
approach to web application security.
QAEngineerswith SecurityKnowledge
QualityAssurance (QA) engineers traditionallyfocus onfunctional
and performancetesting, but those with security expertise add
immense value to the development lifecycle. Security-aware QA

engineers:
Integrate securitytest cases into standard QA processes.
Identifyflaws in business logic, authentication, and
authorization.
Use both manual and automated tools to uncovervulnerabilities
early.
Advocate for secure coding practices and “shift-left” security.
By embedding security into QA, organizations can catch issues
before they reach production, saving time and resources.
Ethical Hackers and PenetrationTesters
Ethical hackers, also known as “white-hat” hackers, and penetration
testers simulate real-world attacks to uncovervulnerabilities before
malicious actors do. Their approach includes:
Using advanced tools and creative techniques to bypass security
controls.
Performing both automatedtesting and manual testing to
mimic attacker behavior.
Providing detailed reports with proof-of-concept exploits and
remediation advice.
Staying updated with the latest threat landscapes and attack
vectors.
Their outsider perspective and adversarial mindset are crucial for
identifying weaknesses that may be overlooked by internal teams.
Third-PartySecurityFirms
Many organizations engage third-party securityfirms to conduct
independent assessments. These firms offer:

Objective, unbiased evaluations ofweb application security.
Access to a broad range of expertise and specialized testing
tools.
Comprehensive reports aligned with industry standards (e.g.,
OWASP, NIST).
Validation for compliance and regulatory requirements.
Third-party assessments add credibility and often reveal hidden
issues, making them a valuable part of a robust security strategy.
Bug BountyHunters
Bug bounty hunters are independent security researchers who
participate in public or private bug bounty programs. They:
Search forvulnerabilities in exchange for monetary rewards or
recognition.
Bring diverse skills and perspectives from around the globe.
Often discover unique or previously unknown vulnerabilities.
Help organizations crowdsource securitytesting via many
methods beyond traditional.
Bug bounty programs harness the collective intelligence ofthe
security community, providing an additional layer of defense.
Each ofthese groups plays a vital role in securing web applications.
By leveraging their combined expertise, organizations can build
resilient, secure, and trustworthyweb platforms.
HowWebApp SecurityTesting is being
Performed ?
Web app securitytesting is a systematic, stages of effort, process for
recognizing and addressing vulnerabilities.

It ultimately begins with scoping and collecting information on the
app. Then starts the standard acquisition of information, with
automated scans using scanning tools like Burp Suite, to identify
common issues like injection vulnerabilities or misconfigurations.
Experts than conduct their manual review ofthe code, looking forthe
more complex bugs found in logic errors. Penetration tests are done
as simulacra of hackers testing the effectiveness ofthe entire
security ofthe web application. The action plan outlining all issues
that need to be fixed is reported in detail, with ranked levels of
importance in some cases. The teams then work collaboratively on
the critical fixes, maybe to introduce secure headers or change input
validation.
Finally, they all must retest properlyto ensure there are no
outstanding issues, and further maintain the integrity ofthe security
ofthe web application.

Aside from the formalized steps, web app securitytesting is best
considered as a team sport that applies, incorporates and adapts
cutting-edge techniques, test models and pre-emptive methods that
are constantly evolving to assess evolving threats. The team can use
threat intelligence feeds to track evolving attack patterns, or do red
team exercises to validate their assumptions of security posture, or
employ chaos engineering to test the application’s abilityto perform
in unforeseen conditions. Instead of just the developers and security
teams working collaboratively, the executive level can also be
engaged in security as part ofthe larger DevOps workflow strategy,
with continuous integration sweeps of checking software security
with founder or CTO signing off at the end; while enabling an AI-
driven testing tools to analyze the software for multiple, niche
vulnerabilities that manual testing may miss.
Ultimately by implementing this whole-of-business approach, the
goal is to achieve not just securityforthe organization, but also
create a security-first mindset throughout the organization.
SecurityTestingTypes
Securitytesting isn’t one-size-fits-all. What works for one company
might fall completelyflat for another. That’s whywe break it into

types-so you can mix and match based on howyour app works, what
data it touches, and honestly, how paranoid you are (or should be).
ManualTesting
There’s still a lot ofvalue in a human just poking around, trying things
out, clicking through weird edge cases. Automated tools are great,
but they don’t have intuition, creativity, orthat “wait, what if I…”
mindset. Manual testers can spot subtle flaws in logic, workflow, and
user experience that machines simply overlook.
Business LogicTesting
Focuses on howthe app behaves, not just the code.
Testers tryto misuse features in ways that still technically
“followthe rules.”
Example? Maybe a coupon code meant for new users works for
returning ones. That logic has gone rogue.
Business logic bugs are some ofthe hardest to spot and fix. They’re
not about “bad code” but about “unexpected consequences.” Imagine
a workflowwhere a refund can be requested twice, orwhere a user
can escalate privileges by chaining together harmless actions. These
issues often require a deep understanding ofthe business and the
app’s intended flow. Automated tools rarely catch these because they
don’t understand intent or context-their job is to look for patterns.
Authentication andAuthorizationTesting
Verifies who can access what-and when.
Tries things like bypassing login, messing with session tokens, or
accessing admin pages as a normal user.
This is where testers get creative: Can you change a user ID in the
URL and see someone else’s data? Can you replay an expired session

token? Can you access features meant for admins bytweaking a
cookie or HTTP header? These are classic “broken access control” and
“broken authentication” issues, and they’re among the most common
real-world vulnerabilities. Manual testers often uncoverthese by
simplythinking, “What if I trythis as a different user?”
PenetrationTesting
Ethical hackers simulate real-world attacks.
Goes beyond checklists-testers chain vulnerabilities, try social
engineering, and look for creative exploits.
Pen testing is like a dress rehearsal for a real attack. Testers try
everything from SQL injection to chaining minor bugs into a major
breach. They’ll also look at your infrastructure, APIs, and even your
cloud setup. The value here is in the unpredictability-good pen
testers think outside the box and often find things automated tools
neverwould.
AutomationTesting
Automation doesn’t replace humans, but it can definitely help.
Especiallyfor catching obvious or repetitive issues that you’d rather
not spend hours manually checking every release.
SecurityScanners (e.g., ZAP, Burp Suite)
Scans for common vulnerabilities like XSS or SQL injection.
Helps map out the app to find interesting endpoints.
Security scanners are yourfirst line of defense. They’re great at
finding low-hanging fruit: outdated libraries, open ports,
misconfigured headers, and the classic OWASP Top 10 issues (think
XSS, SQLi, CSRF). They’re fast and efficient, but they have limits-they
can’t understand business logic, and they sometimes miss issues

that require context. Still, running a scanner regularly is a must.
StaticApplication SecurityTesting (SAST)
Looks at the source code without running it.
Flags insecure functions, hardcoded secrets, or poor coding
patterns.
SAST is like a spell-checkerforyour codebase. It scans for dangerous
functions, hardcoded credentials, and insecure patterns-before your
code even runs. Particularly in large teams or open-source projects,
this is crucial for identifying problems early. Drawbacks? SAST may
produce false positives and is unable to detect problems that only
manifest during runtime, such as logical errors or configuration
errors.
DynamicApplication SecurityTesting (DAST)
Tests the running application.
Acts more like a hackerwould: sending inputs, watching
responses.
Your DAST is your “black box” test: it won’t mind about your code, but
ratherwhat your application does when probed and tested. It is
excellent at identifying real-world vulnerabilities, such as injection
flaws, XSS, and misconfigurations. DASTtools emulate attacks and
observe howyour application reacts to them, making them a must-
have for staging and production environments.
InteractiveApplication SecurityTesting (IAST)
Combines SAST and DAST by monitoring the app from the inside
while it runs.
Provides real-time, context-aware vulnerability detection.
IASTtools instrument your app so they can see both the code and the

data as it flows through the system. More actionable insights and
fewerfalse positives are the results ofthis hybrid approach. IAST is
particularly helpful in contemporary, dynamic environments where
infrastructure and code change frequently. The trade-off? It can add
some performance overhead and usually requires more setup.
Software CompositionAnalysis (SCA)
Scans open-source and third-party components.
Identifies vulnerabilities, licensing risks, and outdated
dependencies.
Most apps today are built on a mountain ofthird-party libraries. SCA
tools scan your dependencies for known vulnerabilities and
compliance issues. They’re essential for avoiding “supply chain”
attacks, where a bug in a libraryyou didn’t write becomes your
problem.
Secret Scanning
Finds hardcoded credentials, API keys, and tokens in source
code and CI/CD pipelines.
Prevents accidental leaks before they become breaches.
For sensitive information in your codebase, secret scanning tools are
similarto metal detectors. They aid in preventing the embarrassing
(and hazardous) disclosure ofAPI keys, passwords, and other secrets
that hackers love to discover.
TestingApproaches
Different approaches change how you test-not just what tools you
use. It’s a bit like wondering, “Howfamiliarwith the system do I need
to be before I attempt to find its weaknesses?”

Black BoxTesting
The tester knows nothing about the internals.
Simulates an outside attacker.
Black box testing is the ultimate outsider perspective. Testers use the
app like regular users would, without access to inside documents or
source code. This method is great for simulating real-world attacks,
but it might cause you to miss some more subtle or deeper issues
that aren’t visible to the public eye.
White BoxTesting
Full access to source code, architecture, and logic.
Can be verythorough.
Source code, documentation, architecture diagrams, the works, the
keys to the kingdom, that white box testing provides fortesters This
enables extensive testing, which is perfect for spotting logical errors
and minor bugs. It also takes a lot oftime and isn’t always practical
unless you’re worried about extremely qualified attackers or insider
threats.
GreyBoxTesting
Somewhere in between.
The tester knows some things, like user roles or general
architecture.
Grey box testing is the sweet spot for manyteams. Testers get
enough info to be effective (like API docs or user roles) but not so
much that they lose the attacker’s perspective. This approach
balances realism and depth, catching a wide range of issues without
requiring total access orworking completely in the dark.

Common WebApplicationVulnerabilities
Web apps have become an integral part of our life today because
people use them for shopping, banking, and connecting with their
friends, but, at the same time, they present numerous challenges.
Recently, I have become more interested in web security. It’s quite
amazing and a bit frightening how manythings can go wrong. One
miscalculation in your steps can lead to app data breaches or leaks.
Let me explain further. Togetherwith my research and other people’s
experience, I will explain some practical ideas regarding the six
common vulnerabilities outlined in the OWASPTop Ten web
application vulnerabilities. So let’s begin.
1. InjectionAttacks
Injection attacks are like someone slipping a prank into your app’s
input fields, turning a harmless form into a disaster. They’re scary
because they’re so simple, an attacker just needs to find a weak spot

in your input handling, and boom, chaos ensues. I remember reading
about a companythat lost millions of records because of a poorly
handled form field. Let’s look at the ways this can happen.
SQL, Command, and LDAPInjection
What’s Happening?
SQL injection is the classic example. An attackertypes something like
' OR '1'='1 into a login form, and ifyour app doesn’t sanitize
inputs, that string can manipulate your database queryto bypass
authentication. Command injection targets the operating system,
letting attackers run arbitrary commands. LDAP injection, less
common but still nasty, messes with directory services, potentially
exposing user data. I saw a demo once where a single quote in a form
field dumped an entire usertable, that’s wild.
Fix
Sanitize Inputs: Always validate and sanitize user inputs. Use
prepared statements or parameterized queries for SQL
frameworks like Django make this a breeze.
Escape Special Characters: For LDAP, escape characters like
* or & . For command injection, avoid passing user input to
system calls.
Use ORM: Object-Relational Mapping tools can abstract queries,
reducing injection risks.
Least Privilege: Run your database or system with minimal
permissions to limit damage.
Code Injection
What’s Happening?
Here the hackers injects the code of PHP or Python which is

executable. This happened manytimes to CMS where attackers
upload a script that ran on the server.You can think of a eval() in
JavaScript, which is scary.
Fix
Avoid Eval: Never use functions like eval() or equivalent in
any language.
InputValidation: Strictlyvalidate inputs to ensure they’re not
executable code.
Sandboxing: Run risky operations in a sandboxed environment if
you must.
Code Reviews: Regularly audit your codebase for dangerous
functions.
XMLInjection
What’s Happening?
XML injection targets apps that parse XML inputs, like APIs or
configuration files. Attackers can manipulate XMLto alter app
behavior or extract data. I read about a case where an attacker
injected XMLto bypass authentication in a SOAP-based API. It’s less
common but still a real threat.
Fix
Validate XML: Use strict XML parsers and schemas to reject
malformed input.
Sanitize Inputs: Strip out dangerous XMLtags or attributes.
Use Safe Libraries: Libraries like libxml2 can help with
secure parsing.
Limit XMLFeatures: Disable external entity processing to

prevent XXE attacks.
2. Cross-Site Scripting (XSS)
It is also a type of injection but slightly different. Here the scripts are
injected into a trusted website in the form of a script from browser
side to another end user.
It’s like setting a concealed snare that activates when a user
accesses yourwebpage. I’ve seen this on old forums where a single
malicious comment could hijack sessions. Let’s break down the types.
Stored, Reflected, DOM-based
What’s Happening?
Stored XSS: The code will run for every userwho accesses the
page because it is stored like a comment on an active script
runner server.
Reflected XSS: The script is embedded in a URL orform input,
affecting users who click a malicious link.
DOM-based XSS: This one’s trickier, it manipulates the browser’s
DOM directly, often without hitting the server. I clicked a demo
link once that stole cookies just bytweaking a URL parameter.
Not cool.
Fix
Encode Outputs: Escape HTML characters (like < and > )
before displaying user input. OWASP’s ESAPI is a great library
that do this job better.
Content SecurityPolicy(CSP): Implement CSP headers to limit
the execution of specific scripts.
FrameworkProtections: React orAngular have built-in XSS
defenses, but verifyyour setup.

Validate Inputs: Filter out dangerous characters server-side,
too.
Server-Side XSS
What’s Happening?
Server-side XSS is basicallywhen someone sneaks their nasty little
scripts into stuffyour server spits out, think error messages,
templates, whatever. Ifyour server’s letting any old dynamic crap
through without scrubbing it clean, yeah, attackers are gonna
pounce. I once saw an app where an error page displayed raw user
input, opening the doorto scripts.
Fix
Sanitize ServerOutput: Ensure all server-generated content is
encoded properly.
Use SafeTemplating: Frameworks like Jinja2 or Handlebars
have escaping built in, use them.
AuditTemplates: Check yourtemplates for places where user
input might sneak in.
CSPHeaders: Again, CSP can limit the damage even if a script
slips through.
Client-Side Framework XSS
What’s Happening?
Ifyou think, widely used frameworks like React orVue are fully
protected, but that doesn’t automatically protect you from making
mistakes.
For instance, ifyou start playing around with things like
dangerouslySetInnerHTML in React and neglect input sanitization,
you’re moving ahead towards trouble.
Yeah, that’s true. I mean, who names something “dangerously”?

They’re not exactly being subtle about the risks. I’ve seen developers
assume frameworks are bulletproof, onlyto get burned by edge
cases.
Fix
Avoid DangerousAPIs: Steer clear of dangerouslySetInnerHTML
or similar unless absolutely necessary.
Sanitize Inputs: Use libraries like DOMPurifyto clean user input
before rendering.
FrameworkBest Practices: Followyourframework’s security
guidelines religiously.
RegularTesting: Use tools like Burp Suite to test for XSS in your
app.
3. Cross-Site Request Forgery(CSRF)
CSRF is basically someone sliding into your account and pretending
to be you like they just forged your signature on something shady.
You didn’t sayyes, but nowyour name’s on it. Sketchy, right?
It tricks a user’s browser into making a request to a site they’re logged
into, without their knowledge. I read about a forum post with a hidden
<img> tag that triggered account deletions.
Howit Works and Prevention
What’s Happening?
CSRF exploits the fact that browsers send cookies automaticallywith
requests. Attackers craft a malicious form or link that submits a
request like transferring moneyfrom your bank account, while you’re
logged in. It’s sneaky because it relies on your existing session.

Fix
Anti-CSRFTokens: Toss in these one-of-a-kind, totally random
tokens for every user session, and don’t just toss them, double-
check them on the server, too. No shortcuts.
SameSite Cookies: Seriously, just slap that SameSite label on
your cookies. That pretty much tells cross-site requests to buzz
off.
ExplicitActions: Require re-entering passwords for sensitive
actions.
Header-BasedAuth: Use tokens in headers instead of relying
solely on cookies.
Token Misuse
What’s Happening?
Even with CSRFtokens, attackers can exploit weak implementations.
For example, iftokens are predictable or not tied to a session,
attackers can bypass them. I once saw a case where a static token
was reused across sessions, It’s a big mistake.
Fix
RandomizeTokens: Ensure tokens are cryptographically secure
and unique per session.
Session Binding: Tie tokens to a specific user session.
Short Expiry: Make tokens expire quicklyto limit theirwindow of
use.
Validate Origin: Check the Origin or Referer headerto
ensure requests come from your site.
API-Specific CSRF

What’s Happening?
APIs, especially RESTful can be vulnerable to CSRF ifthey depend on
cookie-based authentication. Basically, ifyourAPI leans on cookies,
someone can just fool a browser into firing off requests on your
behalf. I’ve seen this in apps where APIs didn’t enforce propertoken
checks.
Fix
Use BearerTokens: Prefertoken-based authentication (like
JWT) in headers over cookies.
CORS Configuration: Set strict CORS policies to limit which
domains can send requests.
Anti-CSRFTokens: Applytokens to API endpoints, not just web
forms.
Disable CookiesforAPIs: If possible, avoid cookies forAPI
authentication.
4. BrokenAccess Control
That’s like tossing your house keys on a public park bench and hoping
forthe best. When your app flakes out on checking permissions,
people end up waltzing into places they’ve got no business being.
Seriously, it’s a recipe for data leaks and nightmare headlines.
Privilege Escalation Issues
What’s Happening?
Privilege escalation is the classic “oops, wrong door” moment, except
worse. Attackers play around with stuff like URLtweaks changing
something like user_id=123 to user_id=456 , just to slide into
accounts that aren’t theirs. Honestly, I once fiddled with a QA app
and, with a lucky guess, landed in some admin dashboard. Wildly
irresponsible (and honestly, kind of hilarious).

Fix
Server-Side Checks: Don’t trust the front end for anything
serious. Always check permissions where the real power is i.e
The server.
Role-BasedAccess Control (RBAC): Map out who should do
what. And actually stick to it.
DenybyDefault: Block access unless explicitly allowed.
LogAccessAttempts: Monitor suspicious activityto catch
issues early.
Insecure Direct Object References (IDOR)
What’s Happening?
IDOR is when your app hands out IDs (like user_id , file_id ) right
in URLs orforms, letting people muck around and poke places they
shouldn’t. Easy exploit, surprisingly common.
For example, changing a URL parameterto access another user’s file.
I’ve seen this in apps where developers assumed users wouldn’t
tamperwith URLs.
Fix
Indirect References: Use random, non-sequential identifiers or
mapping tables.
Access Checks: Verifythe user has permission to access the
specified resource.
Obscure IDs: Avoid exposing database IDs in URLs orAPIs.
Rate Limiting: Limit how many requests a user can make to
guess IDs.
Missing Function-LevelAccess Control

What’s Happening?
This happens when an app doesn’t check permissions for specific
functions, like accessing an admin endpoint by directly navigating to
it. I read about a case where a user accessed a hidden API endpoint
just by guessing its path.
Fix
Function-Level Checks: Validate permissions for every
endpoint orfunction.
CentralizedAuthorization: Use a single authorization layerto
enforce rules.
Hide Sensitive Endpoints: Don’t advertise your secret admin
URLs like it’s a clearance sale.
PenetrationTesting: Regularly unleash the hackers (the good
kind) on your stuffto see what breaks.
5. SecurityMisconfigurations
Security misconfigurations are the “forgot to lock the door” ofweb
vulnerabilities. They’re so preventable, yet so common. These happen
when systems aren’t properly hardened, leaving them open to attack.
It’s like handing attackers a map to yourweaknesses.
Unpatched Systems, Exposed Headers
What’s Happening?
Unpatched systems run outdated software with known exploits.
Exposed headers, like serverversion info or debugging data, give
attackers a starting point. I saw a breach once caused by an old
WordPress plugin with a public exploit. It’s a painful lesson.
Fix

Keep Software Updated: Patch servers, frameworks, and
libraries regularly. Tools like Dependabot can help.
Disable UnnecessaryFeatures: Turn off directory listing or
unused services.
Hide Sensitive Info: Remove verbose error messages and
headers like X-Powered-By .
Use SecurityScanners: Tools like OWASP ZAP can spot
misconfigurations.
Default Configurations
What’s Happening?
Some apps are blessed with some default configurations like
“admin123.” or “Admin@123” or “Administrator” etc. These kinds of
username and passwords are heavily known to hackers and can be
easily guessed, leaving the system vulnerable.
I’ve even seen servers that still have their original database login
credentials, which is basically an open invitation for security
breaches.
Fix
Change Defaults: Always reset default usernames, passwords,
and settings.
Harden Configurations: Follow security best practices foryour
tech stack.
Automated Checks: Use tools to scan for default orweak
configurations.
Documentation: Ensure yourteam knows to avoid default
settings during setup.
Misconfigured Cloud Services
What’s Happening?

Ifyou have not setup the “AWS S3 buckets” or “Azure blobs” properly
then , They can also accidentally expose private information. It’s a
common mistake with big consequences.
Fix
RestrictAccess: Set strict access controls on cloud resources.
Enable Logging: Monitor access to cloud services for suspicious
activity.
Use IAM Policies: Enforce least privilege for cloud users and
services.
RegularAudits: Check cloud configurations with tools like AWS
Trusted Advisor.
6. Insecure Deserialization
Insecure deserialization is a bit of a dark horse, it’s less common but
can be catastrophic. It happens when an app turns untrusted data
into objects without proper checks, potentially letting attackers run
arbitrary code. It’s the type ofthing you neverthink of about until it
attacks you.
Remote Code Execution Risks
What’s Happening?
Attackers craft malicious payloads that, when deserialized, execute
code on your server. I read about a Java app where this led to
ransomware being installed. It’s terrifying how a small flaw can lead to
total compromise.
Fix
Avoid Untrusted Data: Don’t deserialize data from untrusted
sources if possible.

Whitelisting: Only allow specific classes ortypes during
deserialization.
Safe Formats: Use JSON or XMLwith strict parsing instead of
complex objects.
MonitorBehavior: Log and monitor deserialization for unusual
activity.
DataTampering
What’s Happening?
Hackers can mess with serialized data to change how an app acts,
such as switching a user’s role from “guest” to “admin.” I came across
a situation where a deserialized object allowed an attackerto gain
higher privileges without being noticed.
Fix
IntegrityChecks: Use cryptographic signatures to verify
serialized data.
StrictValidation: Validate deserialized objects against expected
structures.
Avoid Complex Objects: Keep serialized data simple to reduce
attack surfaces.
Logging: Track deserialization attempts to spot tampering.
Denial ofService (DoS)via Deserialization
What’s Happening?
Attackers can craft serialized data to consume excessive resources,
crashing your app. Think of it like sending a massive, complex object
that overwhelms the deserialization process. I’ve heard of apps going
down because ofthis kind of attack.
Fix

Limit Resource Usage: Set limits on memory and CPU for
deserialization.
Validate Size: Check the size of serialized data before
processing.
Use Safe Libraries: Libraries like Jackson for Java can be
configured securely.
Rate Limiting: Limit how often users can send serialized data.
Reporting and Remediation:Turning
SecurityFindings intoAction
So, you’ve identified vulnerabilities in yourweb application, great!
That’s halfthe battle. But nowwhat ?
Finding the issues is one thing; reporting them clearly and fixing them
properly is where the real work begins. I’ve been immersed in the
world ofweb security recently, and it’s proving to be quite the
challenge. The trick is to explain the issue at hand without coming
across as a doomsayer, collaborate with developers who might
already be stretched thin, and ensure that the solutions implemented
are truly effective. It’s a learning experience, and I’ll freely admit that
I’ve encountered some reports so unclearthey only added to the
bewilderment.
Let’s break down the crucial stages of reporting and addressing
vulnerabilities, drawing on established best practices and insights
I’ve gathered from my own journey.

1. Writing Effective SecurityReports
A great security report is like a great storywhich grabs you in and
makes you think and does something with what you hear. I’ve come
across reports that were just use oftechnical terms without purpose
and also ones which any layman could understand. The difference?
Structure and focus.
Structure, Clarity, and Impact
What’sthe Issue?
A security report has to present the vulnerability in a simple and
complex language at the same time. If it is too general developers will
not knowwhat to do; if it is too technical managers may ignore it.
Structure it with a clear summary, detailed findings, and actionable
steps.
I once saw a report that just said “XSS found” with no context,
nobody knewwhere to start. Include specifics: where the issue is,
how it was found, and why it matters.
Howto Do It
Use a ClearFormat: Start with an executive summary, then dive
into technical details (vulnerabilitytype, location, impact). End

with remediation steps.
Be Concise: Avoid jargon overload. Say “malicious script in
comment field” instead of “arbitrary code injection vector.”
ShowImpact: Explain the real-world consequences, like data
theft or account takeoverto get buy-in.
Include Evidence: Screenshots, logs, or proof-of-concept code
make the issue tangible.
Prioritizing Findings
What’sthe Issue?
Not all vulnerabilities are the same. We see that presenting the issue
as critical in all cases does not scale and also that which we minimize
serious issues leaves us vulnerable. I have had it with teams that
ignore reports which labeled everything as “urgent” which is a
practice which does not help. Prioritizing findings helps focus efforts
on what matters most.
Howto Do It
Use a RiskFramework: Reference frameworks like CVSS oryour
company’s risk matrix to rank issues.
Highlight Critical Issues: Call out high-impact vulnerabilities
(e.g., SQL injection) upfront.
Group Related Findings: Bundle similar issues to avoid
redundancy.
Provide Context: Explain why a low-severity issue might still
need attention in your app’s context.
Communicating to Stakeholders
What’sthe Issue?
Level of detailing varies from audience to audience. Developers want
technical specifics; executives want the big picture. I once put out a
report which developers really got into but the management team

had no interest in because it was too heavy on tech. The keyto
getting action is to tailoryour report to your audience.
Howto Do It
CustomizefortheAudience: Use plain language for executives,
technical details for developers.
VisualAids: Charts or diagrams can make complex issues easier
to grasp.
Actionable Recommendations: Suggest specific fixes, not just
“patch this.”
FollowUp: Offerto discuss the report with stakeholders to
clarify questions.
2. Risk Rating and CVSS
Assigning risk ratings to vulnerabilities is a tool which helps teams to
prioritize which to fix first, but that’s not to say it is a simple task of 1,
2, or 3. I have seen issues break out in which a flaw is debated to be of
“high” or “medium” severity; we all have our own opinions.
SeverityMetrics
What’sthe Issue?
The present standard forvulnerability assessment is the Common
Vulnerability Scoring System (CVSS) which we turn to forthis
purpose. It provides a 0 to 10 score which is determined byfactors
such as exploitability and impact. For instance a SQL injection which
is easyto play out and which reports back large sets of sensitive data
may receive a 9. But also it is important to note that CVSS is not
without its flaws; it does not always take into account your
application’s unique environment.
Howto Do It

Use CVSS as a Baseline: Calculate scores using the CVSS
calculator (NIST’s site is handy).
AdjustforContext: A “medium” CVSS score might be critical if
it affects your core business logic.
DocumentAssumptions: Explain whyyou rated a vulnerability a
certain way.
Combinewith OtherMetrics: Use internal risk frameworks
alongside CVSS for accuracy.
Qualitativevs. Quantitative Ratings
What’sthe Issue?
CVSS is quantitative, but sometimes a qualitative rating like “low,
medium, high” resonates more with teams. I’ve found that developers
sometimes glaze over numbers but perk up when you say “this could
take down the site.” Balancing both approaches helps.
Howto Do It
Map CVSSto Qualitative: For example, CVSS 7–10 is “critical,” 4–
6 is “medium.”
Explain Impact: Tie ratings to business risks, like downtime or
data leaks.
Be Consistent: Use the same rating system across reports to
avoid confusion.
Involve Stakeholders: Get input from devs or managers to
refine ratings.
Temporal and Environmental Factors
What’sthe Issue?
CVSS includes temporal (e.g., exploit availability) and environmental
(e.g., your app’s setup) factors that can change a score. For instance,
a vulnerabilitywith a public exploit is more urgent. I once

underestimated a flaw because I didn’t know a proof-of-concept was
already out there.
Howto Do It
CheckExploitAvailability: Monitor sites like Exploit-DB for
known exploits.
AssessYourEnvironment: Avulnerability in a public-facing app
is riskierthan in an internal tool.
Update Scores: Reassess ratings as new information (like
patches) emerges.
Document Changes: Note why a score changed in your report.
3. Collaborationwith Developers
Fixing issues isn’t just about bringing up problems, it’s about working
with developers to get solutions in place. I have had the security
teams and developers at each other’s throats due to broken lines of
communication which is a waste of energy.
Fixing andValidatingVulnerabilities
What’sthe Issue?
Developers have a lot of different tasks at once, we aim to make their
jobs easier, not harder.
Provide clear, actionable fixes and verifytheywork. I once suggested
a fix that sounded great in theory but broke the app’s functionality.
Howto Do It
Provide Specific Fixes: Instead of “fix XSS,” say “use
htmlspecialchars for output.”
OfferCode Samples: Share snippets or references to secure
libraries.

Validate Fixes: Test the patch yourselfto ensure it works
without side effects.
BeAvailable: Offerto pairwith devs to troubleshoot trickyfixes.
Building a SecurityCulture
What’sthe Issue?
If security is seen as a separate issue for others to deal with, you are
at a disadvantage. Creating a culture ofwhich all members care
about security issues makes for easier remediation. I’ve seen teams
transform when security became a shared goal.
Howto Do It
Educate, Don’t Lecture: Run workshops or lunch-and-learns on
common vulnerabilities.
CelebrateWins: Acknowledge when devs fix issues well, it builds
goodwill.
Integrate SecurityEarly: Push for secure coding practices in
the design phase.
Be Empathetic: Understand devs’ workloads and constraints.
Handling Resistance
What’sthe Issue?
At times developers push back which may be due to skepticism or
just being very busy. I have had developers bring up that a
vulnerability is a small issue because it’s hard to exploit. Closing that
gap takes tact and persistence.
Howto Do It
ExplaintheWhy: Show howthe vulnerability could hurt the
business or users.

Prioritize Fixes: Help devs focus on high-impact issues first.
CompromiseWhen Needed: If a full fix isn’t feasible, suggest
temporary mitigations.
Escalate Judiciously: Only involve managers if absolutely
necessary.
4. RetestingAfterFixes
Patching a vulnerability is not the end. Retesting to make sure the fix
works and did not create new issues is required. I’ve seen “fixed”
vulnerabilities resurface because nobody checked properly.
EnsuringVulnerabilitiesAre Resolved
What’sthe Issue?
Afix might look good on paper but fail in practice, maybe it only
partially addresses the issue or breaks something else. I once tested a
patch that stopped an XSS attack but caused a login form to crash.
Retesting catches these gotchas.
Howto Do It
ReplicatetheAttack: Trythe original exploit to confirm it’s
blocked.
Test Edge Cases: Check ifthe fix holds under different
conditions (e.g., special characters).
UseAutomatedTools: Scanners like Burp Suite can help verify
fixes.
Document Results: Log what you tested and the outcome for
accountability.
RegressionTesting
What’sthe Issue?

Fixes can break other parts ofthe app, especially in complex systems.
Regression testing ensures the patch doesn’t mess up unrelated
features. I’ve seen a securityfix tank performance because it wasn’t
tested thoroughly.
Howto Do It
Run FullTest Suites: Use automated tests to check core
functionality.
Focus on ImpactedAreas: Test features related to the fix (e.g.,
forms for XSS patches).
MonitorPerformance: Ensure the fix doesn’t slow down the
app.
Involve QA: Work with the QAteam to cover all bases.
Automatedvs. Manual Retesting
What’sthe Issue?
Automated tools can catch obvious issues, but manualtesting often
finds subtle flaws. I’ve had tools miss a DOM-based XSS because it
required specific user actions. Balancing both is key.
Howto Do It
Use Scanners: Tools like OWASPZAP can quicklyverify common
fixes.
ManualTesting: Replicate complex attacks that tools might
miss.
CombineApproaches: Use automation for scale, manual for
depth.
Document Both: Note which tests were automated vs. manual
for clarity.
5. Monitor& Maintain Security

Security is a continuous process, not a one time event. I have seen
applications break into months after a “successful” audit that was
reported out to the team. Monitoring and maintenance keep your app
secure long-term.
Continuous Monitoring
What’sthe Issue?
New issues present themselves constantlywith new exploits,
misconfigurations, or even human error. Which is whywe have
continuous monitoring which identifies issues before theyturn into
full scale disasters. I read about a companythat got hit because they
stopped monitoring after a big security push.
Howto Do It
Set UpAlerts: With Splunk or ELK, you can set up notifications
when any suspicious activity appears in your logs.
VulnerabilityScanning: Schedule Nessus or other similartools,
to scan your system on a regular basis.
MonitorDependencies: Track libraries for known vulnerabilities
using tools like Dependabot.
Incident Response Plan: Have a plan readyforwhen (not if)
something goes wrong.
Patch Management
What’sthe Issue?
Not patching your systems is a dream come true for hackers. Every
day, there are updates and keeping track can be exhausting. Many
teams have found that they regretted holding up patches due to their
schedule.
Howto Do It

Prioritize Patches: Always keep eye on highly sensitive
vulnerabilities like CVSS 7+.
Automate Updates: Use tools to streamline patching where
possible.
Test Patches: Verify patches in a staging environment to avoid
breaking production.
TrackCompliance: Ensure all systems meet your patch policy.
SecurityAwarenessTraining
What’sthe Issue?
Humans are often the weakest link. Developers, admins, even users
can introduce vulnerabilities ifthey’re not trained. I once saw a
breach caused by a dev clicking a phishing link, training could’ve
prevented that.
Howto Do It
RegularTraining: Run sessions on secure coding, phishing, and
best practices.
SimulateAttacks: Use fake phishing emails to test awareness.
Make It Engaging: Gamifytraining to keep it interesting.
Update Content: Keep training current with newthreats.
Best Practices: Incorporating Security
intoYourWebApplications
So you’ve identified vulnerabilities in yourweb application and
reported them, now how do you make it secure in the long term?
That’s where best practices kick in. I’ve given this a lot ofthought
lately, particularly after observing how small tweaks early on can
avert gigantic headaches later on.

Security doesn’t only mean patching things after a break-in has
occurred; it means building applications that are hard to crack from
the beginning. It’s akin to locking your doors when you depart the
house, ratherthan rushing to do so after a robbery has taken place. In
the modern era ofweb apps being the verytargets for attacks on the
digital frontier, from data theft through cross-site scripting (XSS),
writing security into each development phase must be a necessity.
Let’s take a look at some key practices to secure yourweb
applications better, combining industry standards and lessons
learned along the way. Ideally, this will make security less
overwhelming and achievable.
1.Adopt a Shift-Left SecurityMindset
Shift-left security means finding issues early on, long before your
application goes live. I used to think of security as something you

added on at the very last minute, like plugging a leak in a boat after
it’s already on the water.
It’s so much betterwhen you solve security in design and code, less
time wasted, less stress and mayhem. The majority ofvulnerabilities
creep in through development because security isn’t taken into
account right at the beginning.
I used to watch a team frantically patch an XSS vulnerability on the
eve of a product launch, absolute mayhem. By building security early
on, you identify issues when it’s less costly and less time-consuming
to solve them.
Plan SecurityEarly: Involve security experts at the design
phase ofthe project. Do threat modeling (see below) and
establish countermeasures for security risks like data leakage or
unauthorized access beforehand.
EmploySecure Frameworks: Select a framework like Django or
Spring containing default protections against popular attacks
like CSRF or SQL injection.
Train Developers: Educate your staff on secure coding
fundamentals, such as input validation, from resources such as
OWASP’s Top Ten or secure coding standards.
Test Early: Make use oftools like SonarQube to find issues at the
time of development onlyto stop them from going into
production.
Secure Development Lifecycle (SDLC): Integrating security
into each stage, from gathering requirements to designing,
developing, testing, and deploying is crucial. Utilizing
frameworks such as OWASPSAMM is not only a wise move but
also simplifies the process and ensures comprehensive security
coverage.
ActionableTip: When evaluating outside libraries, include solutions
like OWASPDependency-Check in your planning workflow, so you
spot vulnerabilities before anything is integrated into your product.
It’ll save headaches for both engineering and security down the line.

2.Adhere to Secure Coding Practices
Secure programming isn’t simply being cautious, it’s about obeying
established proven rules. I’ve written bad code before and learned the
hard waythat a little bit of discipline can make a big difference.
Secure programming is like a seatbelt: easy but life-saving. Poorly
written code may open doors for attackers. Not validating user inputs,
for example, may result in SQL injection or XSS attacks. I came across
a site that got compromised because they didn’t escape their user
input properly, so small a slip-up, so huge a disaster.
ValidateAll Inputs: Always check what users provide, forms,
URLs, everything, against allowlists. Block anything that looks
suspicious. For example, make sure an email input only accepts
properlyformatted email addresses.
Sanitize Inputs: Escape or remove malicious characters before
doing anything with them. Use libraries like DOMPurifyto clean
up HTML and avoid XSS.
Escape Outputs: Convert special characters (like < or >) into
safe versions before showing them to users to prevent XSS.
Use SafeAPIs: Stick with secure functions like prepared
statements when working with databases to dodge SQL
injection.
Limit ErrorMessages: Don’t reveal too much in error outputs,
no stack traces or DB errors that attackers could use.
Example (Node.jswith Express):
const express = require('express');
const app = express();
const validator = require('validator');
// Validate and sanitize input
app.post('/user', (req, res) => {

const username = validator.escape(req.body.username); //
Sanitize input
if (!validator.isAlphanumeric(username)) {
return res.status(400).send('Invalid username');
}
// Proceed with safe input
});
ActionableTip: Use libraries like validator.js in Node.js orfilter_var()
in PHPto make input validation and sanitization easier and more
reliable.
3. Enact StrongAuthentication and
Authorization
Weak authentication and loose access control are open doors for
attackers. I’ve seen apps get breached due to basic mistakes, like
weak passwords or giving users more access than they need. You
need solid checks to verifywho’s who and tightly control what they
can do.
Multi-FactorAuthentication (MFA): Days of depending solely
on passwords are over. Ask users to prove who they are not just
with a password, but also with a unique code that gets sent to
their phone. It’s an easy extra step that boosts your security big
time.
Secure Password Storage: Keep user credentials safe by using
tried-and-true techniques. Hash passwords with strong
methods like bcrypt, Argon2, or PBKDF2. Weak or old-fashioned
hashing just makes your business a sitting duck.
Role-BasedAccess Control (RBAC): Set up roles with specific
permissions and stick to the principle of least privilege. Don’t
give users more access than necessary.
Session Management: Protect session cookies by marking
them as HttpOnly, Secure, and setting a SameSite attribute.

Also, use short timeouts and invalidate sessions on logout.
Example (Secure Cookie in Express):
app.use(session({
secret: 'your-secret-key',
cookie: {
secure: true,
httpOnly: true,
sameSite: 'strict'
},
resave: false,
saveUninitialized: false
}));
ActionableTip: For user authentication, stick with industry-standard
protocols like OAuth 2.0 or OpenID Connect. Avoid building your own
authentication system unless you want to invite security headaches
down the line.
4. SecureAPIs andThird-Party
Integrations
APIs are super useful, but without proper protection, they can spill
your company’s secrets.
A single unsecured API endpoint can let sensitive data slip out in
mere seconds. Always see your integrations as top-priority and
protect them accordingly.
Implement HTTPS: Always enforce HTTPS to encrypt data
during transmission. Redirect any HTTPtraffic to HTTPS
automatically.
VerifyAPI Requests: Use API keys, OAuth tokens, or JWTs, and
make sure to validate them every single time.
Rate Limiting: Set limits to prevent abuse and defend against

DoS attacks.
AuditThird-PartyIntegrations: Regularly check all libraries
and external services with tools like Snyk or OWASP
Dependency-Check.
ActionableTip: Use API gateways (like AWS API Gateway or Kong) to
manage things like authentication and rate limits in one place.
5. Perform PeriodicAudits and Updates
Ongoing Audits & Updates Think of application security like regular
maintenance on business infrastructure. Staying proactive with
updates prevents minor issues from turning into serious breaches.
It’s surprisingly common for attackers to exploit simply outdated
libraries.
ScheduleAudits: Run security scans everyfew months, tools
like OWASPZAP or Nessus are effective and reputable forfinding
vulnerabilities.
Update Software: Patch yourframeworks, libraries, and servers
regularly. Dependabot can help automate this.
VerifyConfigurations: Disable default credentials, close
unused ports, and harden all settings.
Log and Review: Monitor logs for anything unusual and go
through them regularlyto catch early signs oftrouble.
ActionableTip: Use a vulnerability management process that
prioritizes updates based on severity (like using CVSS scores).
6. ConductThreat Modeling
Threat modeling can totally change the game. It’s about thinking like
a hacker and spotting weak points before they become problems. I’ve
skipped this step before and ended up regretting it, we had to fix
avoidable issues post-launch.

MapYourApplication: Lay out all the pieces, APIs, databases,
user inputs, and howthey interact.
FindThreats: Think about what could go wrong (like
unauthorized access) using a framework like STRIDE.
Prioritize Risks: Focus on what’s likelyto happen or could cause
the most damage.
Plan Defenses: Add the right protections, like encryption or
access controls, based on what you discover.
ActionableTip: Use something like Microsoft’s Threat Modeling Tool
to make this easier and more structured.
7. DefendAgainst Common
Vulnerabilities
The OWASPTopTen is your cheat sheet forweb security risks, and
there are proven fixes for each.
Cross-Site Scripting (XSS): Set strict CSP headers and always
escape output based on context.
Cross-Site Request Forgery(CSRF): Protect forms with CSRF
tokens and validate them on the server.
Insecure Deserialization: Never deserialize data you don’t trust.
Stick to saferformats like JSON.
SecurityMisconfigurations: Lock down your servers, disable
directory listings, delete unused accounts, and keep software
updated.
Example (CSPHeaderin Express):
app.use((req, res, next) => {
res.setHeader("Content-Security-Policy", "script-src 'self'
'trusted-cdn.com'");

next();
});
ActionableTip: Keep doing regulartesting with tools such as OWASP
ZAP or Burp Suite. It’s betterto identifyweaknesses internally
before they’re exploited from the outside.
8. Encrypt Data at Rest and inTransit
Data protection isn’t just best practice, it’s required for compliance
and building trust with your users.
Encrypt inTransit: Use TLS 1.3 with strong ciphers. Disable old
protocols like SSL.
Encrypt at Rest: Secure all stored business data with strong
encryption, such as AES-256.
KeyManagement: Handle encryption keys responsibly.
Leverage enterprise solutions like AWS KMS or HashiCorp Vault to
keep your keys protected and your business compliant.
ActionableTip: Let’s Encrypt offers free SSL/TLS certificates, no
excuse not to use encryption.
9.Test and MonitorPeriodically
Don’t wait for a security incident to find out something’s broken.
Ongoing testing and monitoring are yourfirst lines of defense.
StaticAnalysis (SAST): Use tools like SonarQube to catch
issues while coding.
DynamicTesting (DAST): Run OWASPZAP on your live apps to
see howthey behave under attack.
PenetrationTesting: Simulate real attacks to expose hidden
vulnerabilities.

Logging and Monitoring: Track what’s happening in real time
with tools like the ELK Stack or Splunk.
ActionableTip: Hook security scans into your CI/CD pipelines using
GitHub Actions or Dependabot.
SecurityTesting Standards &
Guidelines:ASimple Guide to Keeping
YourApp Safe
To more easily relate to the idea oftesting yourweb app for security,
think of it like checking your house forvulnerabilities before a storm
(being sure to close the windows). I’ve and have been looking into
security standards lately and, honestly, it’s a lot, but it’s worth it!
Standards are there to help you identify issues and vulnerabilities
before a hacker does. The OWASPTop 10 is the big one and I am going
to take a look at it in some detail, using their official descriptions and
information found on OWASP’s site since it’s so prevalent. There are
other security standards, like NIST and PCI-DSS, and I am going to go
through these standards, too, with their basic descriptions and some
practical suggestions. I hope this makes securitytesting feel a bit
more like a plan and less like a task.
1. OWASPTop 10
The OWASPTop 10 is essentially a “most wanted” list ofthe most
critical securityvulnerabilities found in web applications.
It serves as a crucial reference for developers and security
professionals alike, and I recall my initial reaction to it being, “Wow,
there are a ton ofthings that could potentially go wrong!” This list is
widely acknowledged as the starting point for creating more secure
code, and businesses rely on it to foster a culture of secure
development practices.

Just a heads-up: OWASP is currentlyworking on the 2025 edition of
the Top 10, which is expected to be released in the first half of 2025.
They’re gathering application testing data until December 2024, so if
you have any relevant statistics to contribute, head overto
owasp.org.
For now, let’s explore the 2021 version, which is the most current one
available.
FrequentVulnerabilities and Resolutions
What’sthe Problem?
The OWASPTop 10 for 2021 lists the most critical risks with some
omissions and updates from past editions. Here is the summary
based on OWASP’s official list:
A01: BrokenAccess Control: Moved up from #5, this is
super common, 94% of apps tested had issues here. It’s
when users can access stuffthey shouldn’t, like viewing
another user’s data bytweaking a URL.
A02: Cryptographic Failures: Up from #3, this used to be
called Sensitive Data Exposure. It’s about weak encryption
letting attackers steal data, like passwords.
A03: Injection: Down to #3, this includes SQL injection and
XSS (now part ofthis category). 94% of apps were tested for
injection, and it’s still a big threat. I once saw a login form
hacked with a simple SQLtrick.
A04: Insecure Design: Newfor 2021, this is about flaws in
howthe app is built, like not planning for security early.
A05: SecurityMisconfiguration: Up from #6, this covers
things like unpatched software or exposed settings. It now
includes XML External Entities (XXE).
A06:Vulnerable and Outdated Components: Up from #9,
this is about using older libraries that we know have

problems. This is hard because it doesn’t match CVEs but is
a huge risk.
A07: Identification andAuthentication Failures: Down
from #2, this covers weak passwords or session issues.
Standardized frameworks are helping here.
A08: Software and Data IntegrityFailures: Newfor 2021,
this includes issues like unverified software updates or
insecure deserialization (from 2017’s list).
A09: SecurityLogging and Monitoring Failures: Up from
#10, this is about not catching attacks because of poor
logging. It’s hard to test but critical.
A10: Server-Side Request Forgery(SSRF): Newfrom the
community survey, this is when attackers trick your server
into making harmful requests. It’s less common but has
high impact potential.
Howto Do It
BrokenAccess Control: Check permissions on the server, not
just the UI. Use role-based access control (RBAC).
Cryptographic Failures: Use strong encryption (like TLS 1.3)
and secure key storage. Avoid outdated algorithms like MD5.
Injection: Validate all inputs and use prepared statements for
databases. Escape outputs to block XSS.
Insecure Design: Use threat modeling and secure design
patterns from the start. I learned this the hard waywhen a
rushed project led to flaws.
SecurityMisconfiguration: Keep software updated and hide
sensitive info, like serverversions, in error messages.
Vulnerable Components: Use tools like OWASPDependency-
Check to identifywhere old libraries are present.
Authentication Failures: Implement strong passwords and
multifactor authentication (MFA).
IntegrityFailures: Verify software updates and use secure
CI/CD pipelines.

Logging Failures: Set up logs to catch suspicious activity and
test them regularly.
SSRF: Validate and restrict server requests to trusted URLs only.
Prioritizing OWASPRisks
What’sthe Issue?
With 10 risks, it’s easyto get overwhelmed. Not every issue is critical
foryour app, say, SSRF might be less urgent ifyour app doesn’t make
many server requests. I’ve seen teams waste time on low-risk issues
while ignoring stuff like broken access control, which is a huge deal
since it’s #1 for a reason.
Howto Do It
KnowYourApp: Figure out which risks (like injection or
misconfiguration) are most likelyforyou.
Use CVSS Scores: Combine OWASPwith CVSS to rank severity.
For example, broken access control often scores high.
Focus onTop Risks: Start with A01-A03 (access control, crypto,
injection) since they’re common and dangerous.
TrackProgress: Document which risks you’ve addressed and
why.
TrainingTeams on OWASP
What’sthe Issue?
The OWASPTop 10 is only useful ifyourteam gets it. I once worked
with developers who thought securitywas “someone else’s job,” and it
led to messyfixes. Training everyone starting from coders, testers,
even managers makes security a team effort.
Howto Do It
RunWorkshops: Teach the Top 10 in simple terms, using

examples like SQL injection.
Addto Code Reviews: Check for OWASP issues when reviewing
code.
Use Free Resources: OWASP’s site has cheat sheets and guides,
It’s super helpful.
Encourage Questions: Let yourteam ask about risks without
feeling dumb.
2. NISTGuidelines
NIST guidelines are in a way a verythorough checklist fortesting
security. Not the best read, but will help ensure that you’ve
considered everything.
Testing Procedures and Controls
What’sthe Issue?
NIST (like SP 800-53) gives you steps to test things like access
controls, encryption, and logging. Without a plan, you might miss big
flaws. I saw a team once skip encryption tests and regret it when
sensitive data got exposed.
Howto Do It
FollowNISTSteps: Test key areas like user authentication and
data protection.
ScheduleTests: Run checks regularly, not just once a year.
Keep Records: Write down what you tested and what you found.
Use NISTTools: The NIST Cybersecurity Framework is a great
starting point.
RiskAssessment Processes
What’sthe Issue?

NIST pushes you to think about what could go wrong, like weak
passwords letting attackers in. Skipping this can leave you blind to
risks. I’ve seen apps get hit because nobody assessed the risks of an
exposed API.
Howto Do It
ListThreats: Identify risks like data theft or unauthorized
access.
Measure Impact: Decide how bad each risk would be foryour
app.
Add Protections: Use things like encryption or access limits to
reduce risks.
CheckOften: Update your risk list as your app grows.
Incident Response Planning
What’sthe Issue?
NIST says you need a plan forwhen things go wrong, like a hacker
getting in. Without one, you’re lost in a crisis. I read about a company
that lost hours because they didn’t know howto respond to a breach.
Howto Do It
Make a Plan: Outline howto spot, handle, and recoverfrom
attacks.
Practice It: Run drills to test your plan with yourteam.
Assign Jobs: Decide who does what during a security issue.
Keep It Fresh: Update your plan as newthreats pop up.
3. CWE/SANSTop 25
The CWE/SANS Top 25 is with regard to finding the coding mistakes
that can lead to a large security risk. (i.e., warning list). It is a list for

developers to point out errors that they commonly make.
Most Dangerous Software Errors
What’sthe Issue?
This list covers errors like buffer overflows orweak input validation
that let attackers take overyour app. I once saw a small coding
mistake cause a crash because of a buffer overflow, it was a mess.
Howto Do It
CheckInputs: Always validate what users send to avoid errors
like overflows.
Use Safe Code: Avoid riskyfunctions, like strcpy in C, that
can cause problems.
Secure Logins: Use strong password hashing, like bcrypt, to
avoid auth errors.
ReviewCode: Look forTop 25 errors before launching your app.
StaticAnalysis forCWE
What’sthe Issue?
Tools can catch CWE errors, like bad error handling, before they
become problems. I’ve seen teams miss these because they only did
manual checks, which take ages.
Howto Do It
UseTools: Run static analysis with tools like Fortifyto find
errors.
Scan Early: Check code during development, not just at the end.
Fix Big Issues First: Focus on errors that could cause major
vulnerabilities.
Train Coders: Teach yourteam howto spot and fix CWE issues.

ErrorHandling Best Practices
What’sthe Issue?
Bad error handling, like showing detailed error messages, can give
attackers hints about your system. I saw a site once leak database
info in an error. It’s a big mistake.
Howto Do It
Hide Details: Show users simple error messages, not techy
ones.
Log Safely: Save detailed logs foryourteam, but keep them
secure.
Test Errors: Make sure your app handles errors without
crashing.
Use Frameworks: Tools like Django have safe error handling
built in.
4. PCI-DSS forWeb Security
PCI-DSS is a strict set of rules for apps that handle credit card info. If
you’re running an online store, this is non-negotiable. I’ve heard of
businesses getting huge fines for ignoring it.
SecurityChecklist forPaymentApps
What’sthe Issue?
PCI-DSS requires things like encrypting card data and securing your
network. Ifyou slip up, you risk data theft or penalties. I read about a
store that got fined millions for a weak password.
Howto Do It

Encrypt Card Data: Use strong encryption (like TLS) for card
info at all times.
SecureYourNetwork: Set up firewalls and limit who can access
payment systems.
Test Often: Run scans and penetration tests to meet PCI rules.
LimitAccess: Only let trusted stafftouch cardholder data.
VulnerabilityManagement
What’sthe Issue?
PCI-DSS says you need to find and fix vulnerabilities fast. An
unpatched system could let attackers steal card info. I’ve seen
companies struggle because they didn’t have a clearfix process.
Howto Do It
Scan Regularly: Use tools like Nessus to find weak spots.
Fix Quickly: Patch critical issues within 30 days, per PCI rules.
TrackFixes: Keep a log ofwhat you fixed and when.
Automate Scans: Use tools to make scanning easier.
Third-PartyVendorSecurity
What’sthe Issue?
Ifyou use third-party services, like payment gateways, they must
follow PCI-DSS too. Aweak vendor can be a weak link. I saw a breach
once caused by a vendor’s bad security.
Howto Do It
CheckVendors: Make sure vendors are PCI-compliant.
MonitorThem: Regularly reviewtheir security practices.
Share Less Data: Only give vendors the data they need.
Use Contracts: Add security rules to vendor agreements.

5. ISO 27001 forSecurityManagement
I’m adding ISO 27001 because it’s like a big-picture guide for
managing security across yourwhole organization, not just your app.
It ties everything together nicely.
What’sthe Issue?
Without a clear security plan, your efforts can be all overthe place.
ISO 27001 helps you organize your security processes. I’ve seen
teams get lost without a framework like this.
Howto Do It
Build a SecurityProgram: Set up policies for risks, incidents,
and more.
TrainYourTeam: Make sure everyone knows security basics.
Audit Regularly: Check ifyour processes meet ISO 27001
standards.
Keep Improving: Use audit results to make your security better.
Conclusion
Web application securitytesting isn’t just a technical checkbox, it’s a
mindset, a habit, and, frankly, a necessity in today’s digital world. As
we’ve seen, even a single overlooked vulnerability can lead to massive
breaches, financial losses, and irreparable damage to reputation. The
landscape is always shifting; newthreats emerge, old ones evolve,
and attackers keep finding creative ways to exploit the smallest
cracks.
What stands out is that securitytesting is not a one-off event. It’s an
ongoing process that should be woven into every stage of
development and maintenance. Whether it’s internal securityteams,
QA engineers with a securityfocus, ethical hackers, third-party

specialists, orthe global community of bug bounty hunters, each
brings a unique perspective that strengthens the whole.
Ultimately, the goal is not just to pass a test ortick a compliance box,
but to build resilient, trustworthyweb applications that protect users
and businesses alike. The cost of ignoring security is simplytoo high,
and the benefits of a proactive, layered approach are clear. By making
securitytesting a routine part ofyourworkflow, and by staying
curious, vigilant, and open to newthreats, you can help ensure that
yourweb applications remain safe, reliable, and readyforwhatever
comes next.
We hopethis guide gaveyou real clarityon howto secureyour
web applicationswith confidence. Butwe’re just getting started.
Up next, we’ll shift gears and dive into something just as critical –
“MobileApp SecurityTesting:APractical GuideforModern QA
Teams.” From code tampering to insecure storage and platform-
specific threats, mobile apps bring a whole new set of challenges.
Get readyto explore howto secure your apps where users tap, swipe,
and trust you the most. Staytuned- it’s going to be a deep dive worth
taking.
Witness howourmeticulous approach and cutting-edge
solutions elevated qualityand performanceto newheights.
Beginyourjourneyintotheworld ofsoftwaretesting excellence.
To knowmore referto Tools &Technologies & QAServices.
Ifyouwould liketo learn more aboutthe awesome serviceswe
provide, be sureto reach out.
HappyTesting 🙂

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