CVE-2021-23031
📋 TL;DR
CVE-2021-23031 is an authenticated privilege escalation vulnerability in F5 BIG-IP Advanced WAF and ASM Configuration utility. An authenticated user can exploit this to gain elevated privileges and potentially take full control of affected systems. This affects multiple BIG-IP versions across different release trains.
💻 Affected Systems
- F5 BIG-IP Advanced WAF
- F5 BIG-IP ASM
📦 What is this software?
Big Ip Advanced Web Application Firewall by F5
View all CVEs affecting Big Ip Advanced Web Application Firewall →
Big Ip Advanced Web Application Firewall by F5
View all CVEs affecting Big Ip Advanced Web Application Firewall →
Big Ip Advanced Web Application Firewall by F5
View all CVEs affecting Big Ip Advanced Web Application Firewall →
Big Ip Advanced Web Application Firewall by F5
View all CVEs affecting Big Ip Advanced Web Application Firewall →
Big Ip Advanced Web Application Firewall by F5
View all CVEs affecting Big Ip Advanced Web Application Firewall →
Big Ip Advanced Web Application Firewall by F5
View all CVEs affecting Big Ip Advanced Web Application Firewall →
Big Ip Application Security Manager by F5
View all CVEs affecting Big Ip Application Security Manager →
Big Ip Application Security Manager by F5
View all CVEs affecting Big Ip Application Security Manager →
Big Ip Application Security Manager by F5
View all CVEs affecting Big Ip Application Security Manager →
Big Ip Application Security Manager by F5
View all CVEs affecting Big Ip Application Security Manager →
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise where an authenticated attacker gains root/administrator access, leading to data theft, service disruption, or lateral movement within the network.
Likely Case
Privileged user account takeover allowing configuration changes, policy manipulation, or installation of backdoors in the WAF/ASM systems.
If Mitigated
Limited impact with proper access controls, network segmentation, and monitoring in place to detect and block unauthorized privilege escalation attempts.
🎯 Exploit Status
Requires authenticated access to the Configuration utility. The CWE-78 (OS Command Injection) nature suggests straightforward exploitation once authentication is obtained.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 16.0.1.2, 15.1.3, 14.1.4.1, 13.1.4, 12.1.6, 11.6.5.3 or later
Vendor Advisory: https://support.f5.com/csp/article/K41351250
Restart Required: Yes
Instructions:
1. Download the appropriate hotfix from F5 Downloads. 2. Upload the hotfix to the BIG-IP system. 3. Install the hotfix using the Configuration utility or command line. 4. Reboot the system as required.
🔧 Temporary Workarounds
Restrict Configuration Utility Access
allLimit access to the Configuration utility to only trusted administrative users and networks using firewall rules and access controls.
Implement Least Privilege
allEnsure users only have the minimum necessary privileges and regularly audit user accounts and permissions.
🧯 If You Can't Patch
- Isolate affected systems from internet and restrict internal access to only necessary administrative networks.
- Implement enhanced monitoring and alerting for privilege escalation attempts and unusual Configuration utility activity.
🔍 How to Verify
Check if Vulnerable:
Check BIG-IP version via Configuration utility (System > Platform) or command line. Compare against affected version ranges.Check Version:
tmsh show sys versionVerify Fix Applied:
Verify installed version is equal to or greater than the patched versions listed in the fix section.📡 Detection & Monitoring
Log Indicators:
- Unusual privilege escalation events in system logs
- Multiple failed authentication attempts followed by successful login
- Configuration changes from non-administrative users
Network Indicators:
- Unusual traffic patterns to/from Configuration utility ports
- Multiple authentication requests from single source
SIEM Query:
source="bigip_logs" AND (event_type="privilege_escalation" OR (authentication="success" AND user_role_change="true"))