Cross-Site Request Forgery (CSRF) |
Compound Element ID: 352 (Compound Element Variant: Composite) | Status: Draft |
Description Summary
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.
Scope | Effect |
---|---|
Confidentiality Integrity Availability | 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. |
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 |
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.
profile.php contains the following code.
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:
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 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.
Reference | Description |
---|---|
CVE-2004-1703 | Add user accounts via a URL in an img tag |
CVE-2004-1995 | Add user accounts via a URL in an img tag |
CVE-2004-1967 | Arbitrary code execution by specifying the code in a crafted img tag or URL |
CVE-2004-1842 | Gain administrative privileges via a URL in an img tag |
CVE-2005-1947 | Delete a victim's information via a URL or an img tag |
CVE-2005-2059 | Change another user's settings via a URL or an img tag |
CVE-2005-1674 | Perform actions as administrator via a URL or an img tag |
CVE-2009-3520 | modify password for the administrator |
CVE-2009-3022 | CMS allows modification of configuration via CSRF attack against the administrator |
CVE-2009-3759 | web interface allows password changes or stopping a virtual machine via CSRF |
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. |
Nature | Type | ID | Name | View(s) this relationship pertains to |
---|---|---|---|---|
Requires | Weakness Base | 346 | Origin Validation Error | Research Concepts1000 |
Requires | Weakness Base | 441 | Unintended Proxy/Intermediary | Research Concepts1000 |
Requires | Weakness Base | 613 | Insufficient Session Expiration | Research Concepts1000 |
Requires | Weakness Class | 642 | External Control of Critical State Data | Research Concepts1000 |
ChildOf | Weakness Class | 345 | Insufficient Verification of Data Authenticity | Development Concepts (primary)699 Research Concepts (primary)1000 |
ChildOf | Category | 716 | OWASP Top Ten 2007 Category A5 - Cross Site Request Forgery (CSRF) | Weaknesses in OWASP Top Ten (2007) (primary)629 |
ChildOf | Category | 751 | 2009 Top 25 - Insecure Interaction Between Components | Weaknesses in the 2009 CWE/SANS Top 25 Most Dangerous Programming Errors (primary)750 |
ChildOf | Category | 801 | 2010 Top 25 - Insecure Interaction Between Components | Weaknesses in the 2010 CWE/SANS Top 25 Most Dangerous Programming Errors (primary)800 |
MemberOf | View | 635 | Weaknesses Used by NVD | Weaknesses Used by NVD (primary)635 |
PeerOf | Weakness Base | 79 | Failure to Preserve Web Page Structure ('Cross-site Scripting') | Research Concepts1000 |
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. |
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. |
Mapped Taxonomy Name | Node ID | Fit | Mapped Node Name |
---|---|---|---|
PLOVER | Cross-Site Request Forgery (CSRF) | ||
OWASP Top Ten 2007 | A5 | Exact | Cross Site Request Forgery (CSRF) |
WASC | 9 | Cross-site Request Forgery |
[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. <http://marc.info/?l=bugtraq&m=99263135911884&w=2>. |
OWASP. "Cross-Site Request Forgery (CSRF) Prevention Cheat Sheet". <http://www.owasp.org/index.php/Cross-Site_Request_Forgery_(CSRF)_Prevention_Cheat_Sheet>. |
Edward W. Felten and William Zeller. "Cross-Site Request Forgeries: Exploitation and Prevention". 2008-10-18. <http://freedom-to-tinker.com/sites/default/files/csrf.pdf>. |
Robert Auger. "CSRF - The Cross-Site Request Forgery (CSRF/XSRF) FAQ". <http://www.cgisecurity.com/articles/csrf-faq.shtml>. |
"Cross-site request forgery". Wikipedia. 2008-12-22. <http://en.wikipedia.org/wiki/Cross-site_request_forgery>. |
Submissions | ||||
---|---|---|---|---|
Submission Date | Submitter | Organization | Source | |
PLOVER | Externally Mined | |||
Modifications | ||||
Modification Date | Modifier | Organization | Source | |
2008-07-01 | Eric Dalci | Cigital | External | |
updated Time of Introduction | ||||
2008-09-08 | CWE Content Team | MITRE | Internal | |
updated Alternate Terms, Description, Relationships, Other Notes, Relationship Notes, Taxonomy Mappings | ||||
2009-01-12 | CWE Content Team | MITRE | Internal | |
updated Applicable Platforms, Description, Likelihood of Exploit, Observed Examples, Other Notes, Potential Mitigations, References, Relationship Notes, Relationships, Research Gaps, Theoretical Notes | ||||
2009-03-10 | CWE Content Team | MITRE | Internal | |
updated Potential Mitigations | ||||
2009-05-20 | Tom Stracener | External | ||
Added demonstrative example for profile. | ||||
2009-05-27 | CWE Content Team | MITRE | Internal | |
updated Demonstrative Examples, Related Attack Patterns | ||||
2009-12-28 | CWE Content Team | MITRE | Internal | |
updated Common Consequences, Demonstrative Examples, Detection Factors, Likelihood of Exploit, Observed Examples, Potential Mitigations, Time of Introduction |