CVE-2021-40719
📋 TL;DR
CVE-2021-40719 is a critical deserialization vulnerability in Adobe Connect that allows attackers to execute arbitrary code on affected servers by sending malicious AMF messages. This affects Adobe Connect version 11.2.3 and earlier installations. Attackers can achieve full remote code execution without authentication.
💻 Affected Systems
- Adobe Connect
📦 What is this software?
Connect by Adobe
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the Adobe Connect server, allowing attackers to install malware, steal data, pivot to internal networks, and maintain persistent access.
Likely Case
Remote code execution leading to server takeover, data exfiltration, and deployment of ransomware or backdoors.
If Mitigated
No impact if patched or properly isolated; limited impact if network controls block AMF traffic from untrusted sources.
🎯 Exploit Status
Exploitation requires sending specially crafted AMF messages to the Adobe Connect server endpoint.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 11.2.4 or later
Vendor Advisory: https://helpx.adobe.com/security/products/connect/apsb21-91.html
Restart Required: Yes
Instructions:
1. Download Adobe Connect 11.2.4 or later from Adobe's official site. 2. Backup current installation and data. 3. Run the installer to upgrade. 4. Restart the Adobe Connect service. 5. Verify the version is updated.
🔧 Temporary Workarounds
Network Segmentation
allRestrict access to Adobe Connect servers to trusted IP addresses only using firewall rules.
AMF Traffic Filtering
allBlock or monitor AMF protocol traffic at network perimeter if Adobe Connect is not required externally.
🧯 If You Can't Patch
- Isolate the Adobe Connect server in a restricted network segment with no internet access.
- Implement strict firewall rules to allow only necessary traffic from trusted sources.
🔍 How to Verify
Check if Vulnerable:
Check Adobe Connect version via admin interface or by examining installation files; versions 11.2.3 or earlier are vulnerable.Check Version:
Check the Adobe Connect admin interface under 'Help > About' or examine the version.txt file in the installation directory.Verify Fix Applied:
Verify the version is 11.2.4 or later in the Adobe Connect admin panel or via the installed software version.📡 Detection & Monitoring
Log Indicators:
- Unusual AMF deserialization errors in Adobe Connect logs
- Suspicious POST requests to AMF endpoints
- Unexpected process execution or file creation
Network Indicators:
- AMF protocol traffic from unexpected sources
- Large or malformed AMF messages to Adobe Connect ports
SIEM Query:
source="adobe_connect.log" AND ("deserialization" OR "AMF" OR "CVE-2021-40719")