CVE-2020-4829
📋 TL;DR
This vulnerability in IBM AIX and VIOS allows a local user to exploit the ksu command to gain root privileges through privilege escalation. It affects AIX 7.1, 7.2, and VIOS 3.1 systems. Attackers with local access can elevate their privileges to root.
💻 Affected Systems
- IBM AIX
- IBM VIOS
📦 What is this software?
Aix by Ibm
Aix by Ibm
⚠️ Risk & Real-World Impact
Worst Case
Local attacker gains full root access, compromising the entire system, installing persistent backdoors, accessing all data, and pivoting to other systems.
Likely Case
Privileged user or attacker with initial access escalates to root, enabling complete system control and data exfiltration.
If Mitigated
With proper access controls and patching, impact is limited to unauthorized privilege escalation attempts that are detected and blocked.
🎯 Exploit Status
Requires local user access. Exploit details not publicly disclosed but vulnerability is confirmed by IBM.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: AIX 7.1 TL5 SP4, 7.2 TL3 SP1; VIOS 3.1.2.30
Vendor Advisory: https://www.ibm.com/support/pages/node/6380430
Restart Required: Yes
Instructions:
1. Download appropriate APAR fix from IBM Fix Central. 2. Apply fix using installp or smitty. 3. Reboot system. 4. Verify fix with oslevel -s command.
🔧 Temporary Workarounds
Restrict ksu command access
aixRemove or restrict execute permissions on ksu binary to prevent exploitation
chmod 750 /usr/bin/ksu
chown root:system /usr/bin/ksu
Implement RBAC restrictions
aixUse Role-Based Access Control to limit which users can execute privileged commands
mkuser authorizations=NONE username
chuser roles=username
🧯 If You Can't Patch
- Implement strict access controls and monitor for privilege escalation attempts
- Segment networks to limit lateral movement from compromised systems
🔍 How to Verify
Check if Vulnerable:
Check AIX/VIOS version with oslevel -s and compare to vulnerable versions: 7100-05-04-XXXX, 7200-03-01-XXXX, VIOS 3.1.2.XXCheck Version:
oslevel -sVerify Fix Applied:
Verify oslevel shows patched version: 7100-05-04-1934 or higher, 7200-03-01-1945 or higher, VIOS 3.1.2.30 or higher📡 Detection & Monitoring
Log Indicators:
- Failed or successful ksu command executions
- Unexpected privilege escalation attempts
- Root access from non-privileged users
Network Indicators:
- Unusual outbound connections from AIX/VIOS systems post-exploitation
SIEM Query:
source="aix_logs" AND (event="ksu" OR event="privilege_escalation")