Cross-Site Request Forgery (CSRF)
Compound Element ID: 352 (Compound Element Variant: Composite)Status: Draft
+ Description

Description Summary

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.

Extended Description

When a web server is designed to receive a request from a client without any mechanism for verifying that it was intentionally sent, then it might be possible for an attacker to trick a client into making an unintentional request to the web server which will be treated as an authentic request. This can be done via a URL, image load, XMLHttpRequest, etc. and can result in data disclosure or unintended code execution.

+ Alternate Terms
Session Riding
Cross Site Reference Forgery
+ Time of Introduction
  • Architecture and Design
+ Applicable Platforms



Technology Classes


+ Common Consequences

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.

+ Likelihood of Exploit

Medium to High

+ Detection Methods

Manual Analysis

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.

Effectiveness: 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.

Effectiveness: Limited

+ Demonstrative Examples

Example 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.

The following HTML is intended to allow a user to update a profile.

(Bad Code)
Example Language: HTML 
<form action="/url/profile.php" method="post">
<input type="text" name="firstname"/>
<input type="text" name="lastname"/>
input type="text" name="email"/>
<input type="submit" name="submit" value="Update" />

profile.php contains the following code.

(Bad Code)
Example Language: PHP 
// initiate the session in order to validate sessions


//if the session is registered to a valid user then allow update

if (! session_is_registered("username")) {

echo "invalid session detected!";

// Redirect user to login page


// The user session is valid, so process the request
// and update the information


function update_profile {
// read in the data from $POST and send an update
// to the database
SendUpdateToDatabase($_SESSION['username'], $_POST['email']);
echo "Your profile has been successfully updated.";

This code may look protected since it checks for a valid session. However, CSRF attacks can be staged from virtually any tag or HTML construct, including image tags, links, embed or object tags, or other attributes that load background images.

The attacker can then host code that will silently change the username and email address of any user that visits the page while remaining logged in to the target web application. The code might be an innocent-looking web page such as:

Example Language: HTML 
function SendAttack () { = "";
// send to profile.php

<BODY onload="javascript:SendAttack();">

<form action="" id="form" method="post">
<input type="hidden" name="firstname" value="Funny">
<input type="hidden" name="lastname" value="Joke">
<input type="hidden" name="email">

Notice how the form contains hidden fields, so when it is loaded into the browser, the user will not notice it. Because SendAttack() is defined in the body's onload attribute, it will be automatically called when the victim loads the web page.

Assuming that the user is already logged in to, profile.php will see that a valid user session has been established, then update the email address to the attacker's own address. At this stage, the user's identity has been compromised, and messages sent through this profile could be sent to the attacker's address.

+ Observed Examples
CVE-2004-1703Add user accounts via a URL in an img tag
CVE-2004-1995Add user accounts via a URL in an img tag
CVE-2004-1967Arbitrary code execution by specifying the code in a crafted img tag or URL
CVE-2004-1842Gain administrative privileges via a URL in an img tag
CVE-2005-1947Delete a victim's information via a URL or an img tag
CVE-2005-2059Change another user's settings via a URL or an img tag
CVE-2005-1674Perform actions as administrator via a URL or an img tag
CVE-2009-3520 modify password for the administrator
CVE-2009-3022CMS allows modification of configuration via CSRF attack against the administrator
CVE-2009-3759web interface allows password changes or stopping a virtual machine via CSRF
+ Potential Mitigations

Phase: Architecture and Design

Use anti-CSRF packages such as the OWASP CSRFGuard.

Phase: Implementation

Ensure that your application is free of cross-site scripting issues (CWE-79), because most CSRF defenses can be bypassed using attacker-controlled script.

Phase: 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).

Note that this can be bypassed using XSS (CWE-79).

Phase: 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).

Phase: Architecture and Design

Use the "double-submitted cookie" method as described by Felten and Zeller.

This technique requires Javascript, so it may not work for browsers that have Javascript disabled.

Note that this can probably be bypassed using XSS (CWE-79).

Phase: Architecture and Design

Use the ESAPI Session Management control.

This control includes a component for CSRF.

Phase: Architecture and Design

Do not use the GET method for any request that triggers a state change.

Phase: 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.

Phase: Testing

Use 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. These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.

Use OWASP CSRFTester to identify potential issues.

+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
RequiresWeakness BaseWeakness Base346Origin Validation Error
Research Concepts1000
RequiresWeakness BaseWeakness Base441Unintended Proxy/Intermediary
Research Concepts1000
RequiresWeakness BaseWeakness Base613Insufficient Session Expiration
Research Concepts1000
RequiresWeakness ClassWeakness Class642External Control of Critical State Data
Research Concepts1000
ChildOfWeakness ClassWeakness Class345Insufficient Verification of Data Authenticity
Development Concepts (primary)699
Research Concepts (primary)1000
ChildOfCategoryCategory716OWASP Top Ten 2007 Category A5 - Cross Site Request Forgery (CSRF)
Weaknesses in OWASP Top Ten (2007) (primary)629
ChildOfCategoryCategory7512009 Top 25 - Insecure Interaction Between Components
Weaknesses in the 2009 CWE/SANS Top 25 Most Dangerous Programming Errors (primary)750
ChildOfCategoryCategory8012010 Top 25 - Insecure Interaction Between Components
Weaknesses in the 2010 CWE/SANS Top 25 Most Dangerous Programming Errors (primary)800
MemberOfViewView635Weaknesses Used by NVD
Weaknesses Used by NVD (primary)635
PeerOfWeakness BaseWeakness Base79Failure to Preserve Web Page Structure ('Cross-site Scripting')
Research Concepts1000
+ Relationship Notes

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

+ Research Gaps

This issue was under-reported in CVE until around 2008, when it began to gain prominence. It is likely to be present in most web applications.

+ Theoretical Notes

The CSRF topology is multi-channel:

1. Attacker (as outsider) to intermediary (as user). The interaction point is either an external or internal channel.

2. Intermediary (as user) to server (as victim). The activation point is an internal channel.

+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERCross-Site Request Forgery (CSRF)
OWASP Top Ten 2007A5ExactCross Site Request Forgery (CSRF)
WASC9Cross-site Request Forgery
+ Related Attack Patterns
CAPEC-IDAttack Pattern Name
(CAPEC Version: 1.4)
62Cross Site Request Forgery (aka Session Riding)
111JSON Hijacking (aka JavaScript Hijacking)
+ References
[REF-17] Michael Howard, David LeBlanc and John Viega. "24 Deadly Sins of Software Security". "Sin 2: Web-Server Related Vulnerabilities (XSS, XSRF, and Response Splitting)." Page 37. McGraw-Hill. 2010.
Peter W. "Cross-Site Request Forgeries (Re: The Dangers of Allowing Users to Post Images)". Bugtraq. <>.
OWASP. "Cross-Site Request Forgery (CSRF) Prevention Cheat Sheet". <>.
Edward W. Felten and William Zeller. "Cross-Site Request Forgeries: Exploitation and Prevention". 2008-10-18. <>.
Robert Auger. "CSRF - The Cross-Site Request Forgery (CSRF/XSRF) FAQ". <>.
"Cross-site request forgery". Wikipedia. 2008-12-22. <>.
+ Content History
Submission DateSubmitterOrganizationSource
PLOVERExternally Mined
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigitalExternal
updated Time of Introduction
2008-09-08CWE Content TeamMITREInternal
updated Alternate Terms, Description, Relationships, Other Notes, Relationship Notes, Taxonomy Mappings
2009-01-12CWE Content TeamMITREInternal
updated Applicable Platforms, Description, Likelihood of Exploit, Observed Examples, Other Notes, Potential Mitigations, References, Relationship Notes, Relationships, Research Gaps, Theoretical Notes
2009-03-10CWE Content TeamMITREInternal
updated Potential Mitigations
2009-05-20Tom StracenerExternal
Added demonstrative example for profile.
2009-05-27CWE Content TeamMITREInternal
updated Demonstrative Examples, Related Attack Patterns
2009-12-28CWE Content TeamMITREInternal
updated Common Consequences, Demonstrative Examples, Detection Factors, Likelihood of Exploit, Observed Examples, Potential Mitigations, Time of Introduction