CVE-2021-28490
📋 TL;DR
This vulnerability in OWASP CSRFGuard allows attackers to bypass Cross-Site Request Forgery (CSRF) protection by retrieving the CSRF cookie using only a session token. This affects all applications using OWASP CSRFGuard versions through 3.1.0 for CSRF protection.
💻 Affected Systems
- OWASP CSRFGuard
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers can perform unauthorized actions on behalf of authenticated users, potentially leading to account takeover, data theft, or administrative actions.
Likely Case
Attackers can perform CSRF attacks to modify user data, change settings, or perform actions within the user's permissions.
If Mitigated
With proper controls, impact is limited to applications that rely solely on CSRFGuard without additional security layers.
🎯 Exploit Status
Exploitation requires the attacker to obtain a valid session token, which can be done through various means like XSS or session fixation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.1.1 or later
Vendor Advisory: https://owasp.org/www-project-csrfguard/
Restart Required: Yes
Instructions:
1. Update OWASP CSRFGuard to version 3.1.1 or later. 2. Replace the CSRFGuard JAR file in your application. 3. Restart the application server.
🔧 Temporary Workarounds
Implement additional CSRF tokens
allAdd custom CSRF tokens in forms alongside CSRFGuard to provide layered protection.
Use SameSite cookie attribute
allSet the SameSite attribute on session cookies to restrict cross-site requests.
🧯 If You Can't Patch
- Implement web application firewall (WAF) rules to detect and block CSRF attempts.
- Monitor for unusual user actions and implement rate limiting on sensitive endpoints.
🔍 How to Verify
Check if Vulnerable:
Check the CSRFGuard version in your application's dependencies or JAR file metadata.Check Version:
java -jar csrfguard.jar --version or check Maven/Gradle dependencies.Verify Fix Applied:
Verify that CSRFGuard version is 3.1.1 or later and test CSRF protection with security tools.📡 Detection & Monitoring
Log Indicators:
- Failed CSRF token validations
- Unusual POST requests without referrer headers
Network Indicators:
- Cross-origin requests to sensitive endpoints
- Requests with missing or mismatched CSRF tokens
SIEM Query:
source="app_logs" AND (event="CSRF_FAILURE" OR csrf_token="missing")