Cross-Site Request Forgery (CSRF)
Stable Compound
Structure: Composite
Description
The web application does not, or cannot, sufficiently verify whether a request was intentionally provided by the user who sent the request, which could have originated from an unauthorized actor.
Common Consequences 1
Scope: ConfidentialityIntegrityAvailabilityNon-RepudiationAccess Control
Impact: Gain Privileges or Assume IdentityBypass Protection MechanismRead Application DataModify Application DataDoS: Crash, Exit, or Restart
The consequences will vary depending on the nature of the functionality that is vulnerable to CSRF. An attacker could trick a client into making an unintentional request to the web server via a URL, image load, XMLHttpRequest, etc., which would then be treated as an authentic request from the client - effectively performing any operations as the victim, leading to an exposure of data, unintended code execution, etc. 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 9
Manual AnalysisHigh
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.
Automated Static AnalysisLimited
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.Automated Static Analysis - Binary or BytecodeSOAR Partial
According to SOAR [REF-1479], the following detection techniques may be useful:
```
Cost effective for partial coverage:
```
Bytecode Weakness Analysis - including disassembler + source code weakness analysis
Binary Weakness Analysis - including disassembler + source code weakness analysisManual Static Analysis - Binary or BytecodeSOAR Partial
According to SOAR [REF-1479], the following detection techniques may be useful:
```
Cost effective for partial coverage:
```
Binary / Bytecode disassembler - then use manual analysis for vulnerabilities & anomaliesDynamic Analysis with Automated Results InterpretationHigh
According to SOAR [REF-1479], the following detection techniques may be useful:
```
Highly cost effective:
```
Web Application ScannerDynamic Analysis with Manual Results InterpretationHigh
According to SOAR [REF-1479], the following detection techniques may be useful:
```
Highly cost effective:
```
Fuzz Tester
Framework-based FuzzerManual Static Analysis - Source CodeSOAR Partial
According to SOAR [REF-1479], the following detection techniques may be useful:
```
Cost effective for partial coverage:
```
Focused Manual Spotcheck - Focused manual analysis of source
Manual Source Code Review (not inspections)Automated Static Analysis - Source CodeSOAR Partial
According to SOAR [REF-1479], the following detection techniques may be useful:
```
Cost effective for partial coverage:
```
Source code Weakness Analyzer
Context-configured Source Code Weakness AnalyzerArchitecture or Design ReviewSOAR Partial
According to SOAR [REF-1479], the following detection techniques may be useful:
```
Cost effective for partial coverage:
```
Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)
Formal Methods / Correct-By-ConstructionPotential Mitigations 7
Phase: Architecture and Design
Strategy: 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 [REF-1482].
For example, use anti-CSRF packages such as the OWASP CSRFGuard. [REF-330]
Another example is the ESAPI Session Management control, which includes a component for CSRF. [REF-45]
Phase: Implementation
Ensure that the application is free of cross-site scripting issues (Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')), 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 (Use of Insufficiently Random Values). [REF-332]
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.
Phase: 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. [REF-331]
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.
Demonstrative Examples 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.
Code Example:
Bad
HTML
htmlprofile.php contains the following code.
Code Example:
Bad
PHP
php//if the session is registered to a valid user then allow update*
phpphp// read in the data from $POST and send an update*
phpThis 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:
Code Example:
Attack
HTML
html// send to profile.php* form.submit();}
htmlNotice 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 victim.example.com, 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 10
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-2009-3520modify 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
References 12
24 Deadly Sins of Software Security
Michael Howard, David LeBlanc, and John Viega
McGraw-Hill
2010
ID: REF-44
Cross-Site Request Forgeries (Re: The Dangers of Allowing Users to Post Images)
Peter W
Bugtraq
ID: REF-329
Cross-Site Request Forgery (CSRF) Prevention Cheat Sheet
OWASP
https://cheatsheetseries.owasp.org/cheatsheets/Cross-Site_Request_Forgery_Prevention_Cheat_Sheet.html(2025-07-24)
ID: REF-330
Cross-Site Request Forgeries: Exploitation and Prevention
Edward W. Felten and William Zeller
18-10-2008
ID: REF-331
CSRF - The Cross-Site Request Forgery (CSRF/XSRF) FAQ
Robert Auger
https://www.cgisecurity.com/csrf-faq.html(2025-07-24)
ID: REF-332
Cross-site request forgery
Wikipedia
22-12-2008
ID: REF-333
Top 25 Series - Rank 4 - Cross Site Request Forgery
Jason Lam
SANS Software Security Institute
03-03-2010
ID: REF-334
Preventing CSRF and XSRF Attacks
Jeff Atwood
14-10-2008
ID: REF-335
OWASP Enterprise Security API (ESAPI) Project
OWASP
ID: REF-45
Samy (computer worm)
Wikipedia
ID: REF-956
State-of-the-Art Resources (SOAR) for Software Vulnerability Detection, Test, and Evaluation
Gregory Larsen, E. Kenneth Hong Fong, David A. Wheeler, and Rama S. Moorthy
07-2014
ID: REF-1479
D3FEND: D3-TL Trusted Library
D3FEND
ID: REF-1482
Likelihood of Exploit
Medium
Applicable Platforms
Languages:
Not Language-Specific : Undetermined
Technologies:
Web Server : Undetermined
Modes of Introduction
Architecture and Design
Related Attack Patterns
Alternate Terms
Session Riding
Cross Site Reference Forgery
XSRF
CSRF
Related Weaknesses
Requires:
Origin Validation Error (CWE-346)
Taxonomy Mapping
- PLOVER
- OWASP Top Ten 2007
- WASC
Notes
Relationship
There can be a close relationship between XSS and CSRF (Cross-Site Request Forgery (CSRF)). An attacker might use CSRF in order to trick the victim into submitting requests to the server in which the requests contain an XSS payload. A well-known example of this was the Samy worm on MySpace [REF-956]. The worm used XSS to insert malicious HTML sequences into a user's profile and add the attacker as a MySpace friend. MySpace friends of that victim would then execute the payload to modify their own profiles, causing the worm to propagate exponentially. Since the victims did not intentionally insert the malicious script themselves, CSRF was a root cause.
Theoretical
The CSRF topology is multi-channel:
- Attacker (as outsider) to intermediary (as user). The interaction point is either an external or internal channel.
- Intermediary (as user) to server (as victim). The activation point is an internal channel.