<x> Rails Web App Security Title

WEB APPLICATION
SECURITY IN RAILS
Uri Nativ
RailsIsrael 2012

Uri Nativ
@unativ
Head of Engineering
Klarna Tel Aviv
#railsisrael

Buy Now, Pay Later
1.  Shop online
2.  Receive your goods
3.  Pay

Alice and Bob
<html>
<title>
MicroBlogging
</title>
...
#$@#
%#@&*#$

@results = Micropost.where(
"content LIKE '%#{params[:query]%’”).all
SELECT 'microposts'.*
FROM 'microposts’
WHERE (content LIKE ’%SEARCHSTRING%’)
SQL Injection

FROM 'microposts'
WHERE (content LIKE '%SEARCHSTRING%')
SQL Injection
XXX')
UNION
SELECT 1, email, 1, 1, 1
FROM users --

FROM 'microposts'
WHERE (content LIKE '%XXX')
UNION
SELECT 1, email, 1, 1, 1
FROM users -- %')
SQL Injection

@results = Micropost.where(
"content LIKE ?’, "%#{params[:query]}%”)
).all
SQL Injection - countermeasures

<span class="content">
<%= raw feed_item.content %>
</span>
XSS

<span class="content">
<%= sanitize feed_item.content,
:tags => ['a’]
%>
</span>
XSS - countermeasures

The Attack:
Execute arbitrary code / defacement
JSON is not escaped by default
CSS can be injected as well
Countermeasures:
Never trust data from the users
Use Markdown (e.g. Redcarpet gem)
XSS

CROSS
SITE
REQUEST
FORGERY
CSRF

www.blog.com

2
Click
here for
free iPad
www.freeiPad.com
<form name=“evilform”
action=“www.blog.com/….”>
…
<script>
document.evilform.submit()
</script>
CSRF

www.blog.com

www.freeiPad.com
…
<script>
</script>
CSRF
3

www.blog.com

www.freeiPad.com
…
<script>
</script>
POST /blogpost
Content=“Kick Me!”
CSRF
4

<input
name ="authenticity_token”
type ="hidden”
value ="vyFdEgofzU4oSJJn5wypxq4“
/>
CSRF – Authenticity Token

routes.rb
match '/delete_post/:id',
to: 'microposts#destroy'
CSRF

class ApplicationController <
ActionController::Base
# commented to easily test forms
# protect_from_forgery
...
end
CSRF

The Attack:
Attacker send requests on the victim’s behalf
Doesn’t depend on XSS
Attacked doesn’t need to be logged-in
Countermeasures:
Use Rails CSRF default protection (do not override it)
Use GET for queries
Use POST/DELETE/… when updating data
Add Sign-out link
CSRF

def create
@user = User.new(params[:user])
...
end
Mass Assignment

def create
@user = User.new(params[:user])
...
end
Mass Assignment
{ :name => “gotcha”,
:admin => true }

Blacklist
class User < ActiveRecord::Base
attr_protected :admin
...
end
Mass Assignment - countermeasures

Whitelist
class User < ActiveRecord::Base
attr_accessible
:name,
:email,
:password,
:password_conﬁrmation
...

Global Conﬁg (whitelist)
conﬁg.active_record.
whitelist_attributes = true

The Attack:
Unprotected by default :(
Countermeasures:
Whitelist
Blacklist
Strong Parameters (whitelist)
Rails 4
Logic moved to the controller
Available as a Gem
Mass Assignment

SQL INJECTION
VULNERABILITY IN
RUBY ON RAILS
(CVE-2012-2661)

User.where(
:id => params[:user_id],
:reset_token => params[:token]
)
SELECT users.*
FROM users
WHERE users.id = 6
AND users.reset_token = ’XYZ'
LIMIT 1
CVE-2012-2661 SQL Injection

/users/6/password/edit?token[]
SELECT users.*
FROM users
WHERE users.id = 6
AND users.reset_token IS NULL
LIMIT 1

The Attack:
SQL Injection - Aﬀected version: Rails < 3.2.4
Countermeasures:
Upgrade to Rails 3.2.4 or higher

-------------------------------------------------
| Warning Type | Total |
-------------------------------------------------
| Cross Site Scripting | 2 |
| Cross-Site Request Forgery | 1 |
| Denial of Service | 1 |
| Redirect | 1 |
| SQL Injection | 4 |
-------------------------------------------------
Brakeman

Know the threats – OWASP top 10
Follow Rails conventions
Ruby on Rails Security Guide
http://guides.rubyonrails.org/security.html
The Ruby on Rails security project
http://www.rorsecurity.info
Rails security mailing list:
http://groups.google.com/group/rubyonrails-security
Conclusions

Daniel Amselem for pair programming
Irit Shainzinger for the cool graphics
Michael Hartl for his microblogging app tutorial
Thanks to…

Pay Online – Safer and Simpler
https://github.com/unativ/sample_app

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