CVE-2021-25653
📋 TL;DR
This CVE describes a local privilege escalation vulnerability in Avaya Aura Appliance Virtualization Platform Utilities (AVPU) that allows authenticated local users to gain elevated privileges. It affects organizations running Avaya AVPU versions 8.0.0.0 through 8.1.3.1.
💻 Affected Systems
- Avaya Aura Appliance Virtualization Platform Utilities (AVPU)
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
An authenticated local attacker gains root/administrator access to the AVPU system, potentially compromising the entire Avaya infrastructure and accessing sensitive communications data.
Likely Case
A malicious insider or compromised account escalates privileges to install backdoors, exfiltrate data, or pivot to other systems in the network.
If Mitigated
With proper access controls and monitoring, impact is limited to the specific AVPU instance, though privilege escalation still enables significant system compromise.
🎯 Exploit Status
Exploitation requires local access but is likely straightforward once access is obtained.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 8.1.3.2 and later
Vendor Advisory: https://support.avaya.com/css/P8/documents/101076479
Restart Required: Yes
Instructions:
1. Download AVPU version 8.1.3.2 or later from Avaya support portal. 2. Backup current configuration. 3. Apply the update following Avaya's upgrade procedures. 4. Restart the AVPU appliance.
🔧 Temporary Workarounds
Restrict local user access
allLimit local user accounts to only essential personnel and implement strict access controls.
Implement privilege separation
linuxUse sudo restrictions and least privilege principles for all local accounts.
# Example: Add to /etc/sudoers with visudo
# user ALL=(ALL) NOPASSWD: /usr/bin/specific_command
🧯 If You Can't Patch
- Implement strict network segmentation to isolate AVPU systems from critical infrastructure
- Enhance monitoring and alerting for privilege escalation attempts and unusual local user activity
🔍 How to Verify
Check if Vulnerable:
Check AVPU version via web interface or SSH: avpu --version or check /etc/avpu/versionCheck Version:
avpu --version || cat /etc/avpu/versionVerify Fix Applied:
Verify version is 8.1.3.2 or later and check Avaya security bulletins for confirmation📡 Detection & Monitoring
Log Indicators:
- Unusual privilege escalation attempts in system logs
- Unexpected sudo or su commands from non-admin users
- Changes to user privilege levels
Network Indicators:
- Unusual outbound connections from AVPU systems
- SSH/RDP connections to AVPU from unexpected sources
SIEM Query:
source="avpu_logs" AND (event_type="privilege_escalation" OR user="*" AND action="sudo" OR action="su")