CVE-2023-26756
📋 TL;DR
The login page of Revive Adserver v5.4.1 is vulnerable to brute force attacks, allowing attackers to guess user credentials through repeated login attempts. This affects all users running the vulnerable version of Revive Adserver. The vendor disputes the severity, claiming existing rate limits and password policies provide sufficient mitigation.
💻 Affected Systems
- Revive Adserver
📦 What is this software?
Adserver by Revive
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain administrative access to the ad server, allowing them to modify ad campaigns, inject malicious content, or compromise the entire system.
Likely Case
Attackers gain access to user accounts with weak passwords, potentially compromising ad campaigns and user data.
If Mitigated
With proper rate limiting and strong password policies, attackers would be unable to successfully brute force credentials.
🎯 Exploit Status
Brute force attacks are well-understood and easily automated with tools like Hydra or Burp Suite Intruder.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: N/A
Vendor Advisory: https://www.revive-adserver.com/security/response-to-cve-2023-26756/
Restart Required: No
Instructions:
No official patch. The vendor recommends relying on existing rate limiting and password policies. Consider upgrading to the latest version for general security improvements.
🔧 Temporary Workarounds
Implement Web Application Firewall (WAF)
allConfigure WAF rules to block excessive login attempts from single IP addresses.
Enable CAPTCHA
allAdd CAPTCHA challenges to the login page to prevent automated brute force attempts.
🧯 If You Can't Patch
- Enforce strong password policies (minimum 12 characters, complexity requirements).
- Implement account lockout after 5-10 failed login attempts.
- Monitor login logs for suspicious patterns (multiple failed attempts from same IP).
🔍 How to Verify
Check if Vulnerable:
Check if running Revive Adserver v5.4.1 by reviewing the version in the admin interface or checking the source code.Check Version:
Check the admin dashboard or view the source code for version information.Verify Fix Applied:
Verify that rate limiting is enabled and working by testing with multiple rapid login attempts.📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts from same IP address
- Unusual login patterns outside business hours
Network Indicators:
- High volume of POST requests to /www/admin/login.php
SIEM Query:
source="revive_logs" action="login_failed" | stats count by src_ip | where count > 10🔗 References
- http://seclists.org/fulldisclosure/2024/Apr/27
- https://googleinformationsworld.blogspot.com/2023/04/revive-adserver-541-vulnerable-to-brute.html
- https://www.esecforte.com/login-page-brute-force-attack/
- https://www.revive-adserver.com/security/response-to-cve-2023-26756/
- http://seclists.org/fulldisclosure/2024/Apr/27
- https://googleinformationsworld.blogspot.com/2023/04/revive-adserver-541-vulnerable-to-brute.html
- https://www.esecforte.com/login-page-brute-force-attack/
- https://www.revive-adserver.com/security/response-to-cve-2023-26756/
