CVE-2021-20108
📋 TL;DR
This vulnerability in ManageEngine Asset Explorer Agent allows remote attackers to cause a denial of service through memory exhaustion. By repeatedly sending commands to port 9000, attackers can trigger memory leaks that eventually crash the agent. Organizations using Asset Explorer Agent version 1.0.34 are affected.
💻 Affected Systems
- ManageEngine Asset Explorer Agent
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete denial of service for asset management functionality, potentially disrupting IT operations and security monitoring capabilities.
Likely Case
Agent crashes requiring manual restart, interrupting asset scanning and inventory collection until service is restored.
If Mitigated
Minimal impact with proper network segmentation and monitoring in place to detect and block attack attempts.
🎯 Exploit Status
Exploitation requires only network access to port 9000 and ability to send HTTPS commands. No authentication or special privileges needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.0.35 or later
Vendor Advisory: https://www.manageengine.com/products/asset-explorer/security-updates/cve-2021-20108.html
Restart Required: Yes
Instructions:
1. Download latest Asset Explorer Agent from ManageEngine website. 2. Stop the agent service. 3. Install the updated version. 4. Restart the agent service.
🔧 Temporary Workarounds
Network Access Control
allRestrict access to port 9000/tcp to only authorized ManageEngine servers
Firewall Block
windowsBlock incoming connections to port 9000 on agent systems
netsh advfirewall firewall add rule name="Block AEAgent Port" dir=in action=block protocol=TCP localport=9000
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Asset Explorer agents from untrusted networks
- Deploy network monitoring to detect and alert on unusual traffic patterns to port 9000
🔍 How to Verify
Check if Vulnerable:
Check agent version in Asset Explorer console or run 'aeagent --version' on agent systemCheck Version:
aeagent --versionVerify Fix Applied:
Confirm agent version is 1.0.35 or later and monitor for memory leaks during normal operation📡 Detection & Monitoring
Log Indicators:
- Repeated agent crashes
- High memory usage by aeagent process
- Failed connection attempts to ManageEngine server
Network Indicators:
- High volume of HTTPS traffic to port 9000
- Unusual command patterns (NEWSCAN, DELTASCAN) from non-ManageEngine sources
SIEM Query:
source_port=9000 AND (command="NEWSCAN" OR command="DELTASCAN") AND NOT src_ip IN [authorized_manageengine_servers]