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CWE
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Cross-Site Request Forgery (CSRF)

ID: 352Date: (C)2012-05-14   (M)2017-12-01
Type: compound elementStatus: DRAFT
Abstraction Type: Variant





Description

The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request.

Likelihood of Exploit: Medium to High

Applicable Platforms
Language Class: Language-independent
Technology Class: Web-Server

Time Of Introduction

  • Architecture and Design

Related Attack Patterns

Common Consequences

ScopeTechnical ImpactNotes
Confidentiality
Integrity
Availability
Non-Repudiation
Access_Control
 
Gain privileges / assume identity
Bypass protection mechanism
Read application data
Modify application data
DoS: crash / exit / restart
 
The consequences will vary depending on the nature of the functionality that is vulnerable to CSRF. An attacker could effectively perform any operations as the victim. If the victim is an administrator or privileged user, the consequences may include obtaining complete control over the web application - deleting or stealing data, uninstalling the product, or using it to launch other attacks against all of the product's users. Because the attacker has the identity of the victim, the scope of CSRF is limited only by the victim's privileges.
 

Detection Methods

NameDescriptionEffectivenessNotes
Manual Analysis
 
This weakness can be detected using tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session.
Specifically, manual analysis can be useful for finding this weakness, and for minimizing false positives assuming an understanding of business logic. However, it might not achieve desired code coverage within limited time constraints. For black-box analysis, if credentials are not known for privileged accounts, then the most security-critical portions of the application may not receive sufficient attention.
Consider using OWASP CSRFTester to identify potential issues and aid in manual analysis.
 
High
 
 
Automated Static Analysis
 
CSRF is currently difficult to detect reliably using automated techniques. This is because each application has its own implicit security policy that dictates which requests can be influenced by an outsider and automatically performed on behalf of a user, versus which requests require strong confidence that the user intends to make the request. For example, a keyword search of the public portion of a web site is typically expected to be encoded within a link that can be launched automatically when the user clicks on the link.
 
Limited
 
 

Potential Mitigations

PhaseStrategyDescriptionEffectivenessNotes
Architecture and Design
 
Libraries or Frameworks
 
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
For example, use anti-CSRF packages such as the OWASP CSRFGuard. [R.352.3]
Another example is the ESAPI Session Management control, which includes a component for CSRF. [R.352.9]
 
  
Implementation
 
 Ensure that the application is free of cross-site scripting issues (CWE-79), because most CSRF defenses can be bypassed using attacker-controlled script.
 
  
Architecture and Design
 
 Generate a unique nonce for each form, place the nonce into the form, and verify the nonce upon receipt of the form. Be sure that the nonce is not predictable (CWE-330). [R.352.5]
 
 Note that this can be bypassed using XSS (CWE-79).
 
Architecture and Design
 
 Identify especially dangerous operations. When the user performs a dangerous operation, send a separate confirmation request to ensure that the user intended to perform that operation.
 
 Note that this can be bypassed using XSS (CWE-79).
 
Architecture and Design
 
 Use the "double-submitted cookie" method as described by Felten and Zeller:
When a user visits a site, the site should generate a pseudorandom value and set it as a cookie on the user's machine. The site should require every form submission to include this value as a form value and also as a cookie value. When a POST request is sent to the site, the request should only be considered valid if the form value and the cookie value are the same.
Because of the same-origin policy, an attacker cannot read or modify the value stored in the cookie. To successfully submit a form on behalf of the user, the attacker would have to correctly guess the pseudorandom value. If the pseudorandom value is cryptographically strong, this will be prohibitively difficult.
This technique requires Javascript, so it may not work for browsers that have Javascript disabled. [R.352.4]
 
 Note that this can probably be bypassed using XSS (CWE-79), or when using web technologies that enable the attacker to read raw headers from HTTP requests.
 
Architecture and Design
 
 Do not use the GET method for any request that triggers a state change.
 
  
Implementation
 
 Check the HTTP Referer header to see if the request originated from an expected page. This could break legitimate functionality, because users or proxies may have disabled sending the Referer for privacy reasons.
 
 Note that this can be bypassed using XSS (CWE-79). An attacker could use XSS to generate a spoofed Referer, or to generate a malicious request from a page whose Referer would be allowed.
 

Relationships
This can be resultant from XSS, although XSS is not necessarily required.

Related CWETypeViewChain
CWE-352 ChildOf CWE-814 Category CWE-809  

Demonstrative Examples   (Details)

  1. This example PHP code attempts to secure the form submission process by validating that the user submitting the form has a valid session. A CSRF attack would not be prevented by this countermeasure because the attacker forges a request through the user's web browser in which a valid session already exists.

Observed Examples

  1. CVE-2004-1703 : Add user accounts via a URL in an img tag
  2. CVE-2004-1995 : Add user accounts via a URL in an img tag
  3. CVE-2004-1967 : Arbitrary code execution by specifying the code in a crafted img tag or URL
  4. CVE-2004-1842 : Gain administrative privileges via a URL in an img tag
  5. CVE-2005-1947 : Delete a victim's information via a URL or an img tag
  6. CVE-2005-2059 : Change another user's settings via a URL or an img tag
  7. CVE-2005-1674 : Perform actions as administrator via a URL or an img tag
  8. CVE-2009-3520 : modify password for the administrator
  9. CVE-2009-3022 : CMS allows modification of configuration via CSRF attack against the administrator
  10. CVE-2009-3759 : web interface allows password changes or stopping a virtual machine via CSRF

For more examples, refer to CVE relations in the bottom box.

White Box Definitions
None

Black Box Definitions
None

Taxynomy Mappings

TaxynomyIdNameFit
PLOVER  Cross-Site Request Forgery (CSRF)
 
 
OWASP Top Ten 2007 A5
 
Cross Site Request Forgery (CSRF)
 
Exact
 
WASC 9
 
Cross-site Request Forgery
 
 

References:

  1. Michael Howard David LeBlanc John Viega .24 Deadly Sins of Software Security. McGraw-Hill. Section:'"Sin 2: Web-Server Related Vulnerabilities (XSS, XSRF, and Response Splitting)." Page 37'. Published on 2010.
  2. Peter W .Cross-Site Request Forgeries (Re: The Dangers of Allowing Users to Post Images). Bugtraq.
  3. OWASP .Cross-Site Request Forgery (CSRF) Prevention Cheat Sheet.
  4. Edward W. Felten William Zeller .Cross-Site Request Forgeries: Exploitation and Prevention. 2008-10-18.
  5. Robert Auger .CSRF - The Cross-Site Request Forgery (CSRF/XSRF) FAQ.
  6. .Cross-site request forgery. Wikipedia. 2008-12-22.
  7. Jason Lam .Top 25 Series - Rank 4 - Cross Site Request Forgery. SANS Software Security Institute. 2010-03-03.
  8. Jeff Atwood .Preventing CSRF and XSRF Attacks. 2008-10-14.
  9. OWASP .OWASP Enterprise Security API (ESAPI) Project.
CVE    488
CVE-2002-2426
CVE-2006-6741
CVE-2007-1489
CVE-2007-1520
...

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