Correct the most common web development security mistakes - Eric Vanderburg

Correct the most common
web development security mistakes
© 2015 Property of JurInnov Ltd. All Rights Reserved
Eric A. Vanderburg, MBA, CISSP
Director, Information Systems and Security
Computer Forensic and Investigation Services

© 2015 Property of JurInnov Ltd. All Rights Reserved© 2015 Property of JurInnov Ltd. All Rights Reserved
Security mistakes
• Current state
• Common web development mistakes
– Security misconfiguration
– URL access
– Redirects and forwards
– Direct object references
– Storage locations
– Transport layer
2

Threats
Impacts
Threat and Impact

Current state
 Average breach costs $214 per record
 Average organizational cost $7.2 million per
incident
 Risk and compliance budgets expected to
increase by 21%
4

$548 million
The US government
is increasing cyber
security R&D by 35%
to $548 million next
year
More organized
outside attacks
Facts and Figures

Security misconfiguration
• Secure web servers and dependencies
• Source code repositories
• All credentials should change in production
6

Impact
• Install backdoor through missing network or
server patch
• XSS flaw exploits due to missing application
framework patches
• Unauthorized access to default accounts,
application functionality or data, or unused but
accessible functionality due to poor server
configuration
7

Protection
• Verify your system’s configuration management
– Secure configuration “hardening”
– Must cover entire platform and application
– Keep up with patches for OS and components
– Analyze security effects of changes
• Can you export the application configuration
– Build reporting into your process
• Verify the implementation
– If you can’t verify it, it isn’t secure
– Scanning finds generic configuration and missing patch problems
8

URL access
• Failure to restrict URL access
• How it happens:
– Displaying only authorized links and menu
choices
– This is called presentation layer access control,
and doesn’t work
– Attacker simply forges direct access to
‘unauthorized’ pages
9

Example
• Attacker notices the URL indicates his role
/user/getAccounts
• Attacker modifies it to another directory
/admin/getAccounts, or
/manager/getAccounts
10
• Attacker views more
accounts than just
their own

Impact
• Attackers invoke functions and services they’re
not authorized for
• Access other user’s accounts and data
• Perform privileged actions
11

Protection
• For each URL, a site needs to do 3 things
– Restrict access to authenticated users (if not public)
– Enforce any user or role based permissions (if
private)
– Completely disallow requests to unauthorized page
types (e.g., config files, log files, source files, etc.)
• Verify your architecture
– Use a simple, positive modeevery layer
– Be sure you actually have a mechanism at l at every
layer
12

Verify the implementation
• Forget automated analysis approaches
• Verify that each URL in your application is protected by
either
– An external filter, like Java EE web.xml or a commercial product
– Or internal checks in YOUR code – Use ESAPI’s
isAuthorizedForURL() method
• Verify the server configuration disallows requests to
unauthorized file types
• Use WebScarab or your browser to forge unauthorized
requests
13

Redirects and forwards
• Unvalidated redirects and forwards
• Web application redirects send victims to a site
of the attacker’s choice
• Forwards
– They internally send the request to a new page in
the same application
– Sometimes parameters define the target page
– Used to bypass authentication and authorization
checks
14

Impact
• Redirect victim to phishing or malware site
• Attacker’s request is forwarded past security
checks, allowing unauthorized function or data
access
15

Protecting redirects
• Avoid using redirects and forwards as much as you can
• If used, don’t involve user parameters in defining the
target URL
• If you ‘must’ involve user parameters, then either
– Validate each parameter to ensure its valid and
authorized for the current user, or
– (preferred) – Use server side mapping to translate
choice provided to user with actual target page
• Defense in depth: For redirects, validate the target URL
after it is calculated to make sure it goes to an
authorized external site
16

Protecting forwards
• Ideally, you’d call the access controller to make
sure the user is authorized before you perform
the forward (with ESAPI, this is easy)
• With an external filter, like Siteminder, this is not
very practical
• Next best is to make sure that users who can
access the original page are ALL authorized to
access the target page.
17

Direct object references
• Insecure direct object references
• Caused by failed access control at the
presentation layer allowing attackers to modify
parameter values.
– Only listing the ‘authorized’ objects for the
current user, or
– Hiding the object references in hidden fields and
then not enforcing these restrictions on the
server side
18

Impact
• Impact
– Unauthorized access
– Data breach
– Data corruption
19

Example
• www.banking.com/user?acct=10579
• Attacker notices his acct parameter is 10579
?acct=10579
• He modifies it to a nearby number
?acct=10580
• Attacker views the victim’s account information
20

Protection techniques
• Eliminate the direct object reference
• Replace them with a temporary mapping value
• ESAPI provides support for numeric & random
mappings
» IntegerAccessReferenceMap
» RandomAccessReferenceMap
• Validate the direct object reference
• Verify the parameter value is properly formatted
• Verify the user is allowed to access the target object
• Verify the requested mode of access is allowed to the
target object (e.g., read, write, delete)
21

Storage locations
• Insecure Cryptographic Storage
– Failure to identify all sensitive data
– Failure to identify all the places that this sensitive
data gets stored
– Databases, files, directories, log files, backups,
etc.
– Failure to properly protect this data in every
location
22

Impact
• Attackers access or modify confidential or private
information
– e.g, credit cards, health care records, financial data
(yours or your customers)
• Attackers extract secrets to use in additional attacks
• Company embarrassment, customer dissatisfaction, and
loss of trust
• Expense of cleaning up the incident, such as forensics,
sending apology letters, reissuing thousands of credit
cards, providing identity theft insurance
• Business gets sued and/or fined
23

• Verify your architecture
– Identify all sensitive data
– Identify all the places that data is stored
– Ensure threat model accounts for possible attacks
– Use encryption to counter the threats, don’t just ‘encrypt’
the data
• Protect with appropriate mechanisms
– File encryption, database encryption, data element
encryption
24

• Use the mechanisms correctly
– Use standard strong algorithms
– Generate, distribute, and protect keys properly
– Be prepared for key change
• Verify the implementation
– A standard strong algorithm is used, and it’s the proper algorithm
for this situation
– All keys, certificates, and passwords are properly stored and
protected
– Safe key distribution and an effective plan for key change are in
place
– Analyze encryption code for common flaws
25

Transport Layer
• Insufficient Transport Layer Protection
– Failure to identify all sensitive data
– Failure to identify all the places that this sensitive
data is sent
– On the web, to backend databases, to business
partners, internal communications
– Failure to properly protect this data in every
location
26

Impact
• Attackers access or modify confidential or private
information
– e.g, credit cards, health care records, financial data
(yours or your customers)
• Attackers extract secrets to use in additional attacks
• Company embarrassment, customer dissatisfaction, and
loss of trust
• Expense of cleaning up the incident, such as forensics,
sending apology letters, reissuing thousands of credit
cards, providing identity theft insurance
• Business gets sued and/or fined
27

• Protect with appropriate mechanisms
– Use TLS on all connections with sensitive data
– Individually encrypt messages before transmission (XML-
Encryption)
– Sign messages before transmission (XML-Signature)
• Correct use
– Use standard strong algorithms (disable old SSL
algorithms)
– Manage keys/certificates properly
– Verify SSL certificates before using them
28

Questions

For assistance or additional information
• Phone: 216-664-1100
• Web: www.jurinnov.com
• Email: eric.vanderburg@jurinnov.com
• Twitter: @evanderburg
• Facebook: www.facebook.com/VanderburgE
• Linkedin: www.linkedin.com/in/evanderburg
• Youtube: www.youtube.com/user/evanderburg
JurInnov Ltd.
The Idea Center
1375 Euclid Avenue, Suite 400
Cleveland, Ohio 44115

Correct the most common web development security mistakes - Eric Vanderburg

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