CVE-2021-25693
📋 TL;DR
CVE-2021-25693 is a null pointer dereference vulnerability in Teradici PCoIP Agent that allows attackers to cause a Denial of Service (DoS) by crashing the service. This affects organizations using Teradici PCoIP Agent for remote desktop access across multiple versions. The vulnerability requires network access to the PCoIP service.
💻 Affected Systems
- Teradici PCoIP Agent
📦 What is this software?
Pcoip Agent by Teradici
Pcoip Agent by Teradici
Pcoip Agent by Teradici
⚠️ Risk & Real-World Impact
Worst Case
Complete service disruption of PCoIP remote desktop sessions, preventing users from accessing virtual desktops or workstations.
Likely Case
Intermittent service crashes affecting PCoIP connectivity, requiring service restarts to restore functionality.
If Mitigated
Limited impact with proper network segmentation and monitoring, allowing quick detection and recovery.
🎯 Exploit Status
Null pointer dereference vulnerabilities typically require minimal exploitation complexity once the attack vector is identified.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Teradici advisory for specific patched versions
Vendor Advisory: https://advisory.teradici.com/security-advisories/79/
Restart Required: Yes
Instructions:
1. Review Teradici advisory for affected versions. 2. Download and install the latest patched version from Teradici. 3. Restart the PCoIP Agent service. 4. Verify the update was successful.
🔧 Temporary Workarounds
Network Segmentation
allRestrict network access to PCoIP service port (typically 4172/TCP) to trusted hosts only.
Firewall Rules
allImplement firewall rules to block untrusted sources from accessing PCoIP service.
🧯 If You Can't Patch
- Implement strict network access controls to limit PCoIP service exposure
- Monitor PCoIP service logs for crash events and implement automated alerting
🔍 How to Verify
Check if Vulnerable:
Check PCoIP Agent version against Teradici's advisory; versions prior to the patched release are vulnerable.Check Version:
Windows: Check PCoIP Agent in Programs and Features. Linux: Check package version via package manager.Verify Fix Applied:
Verify PCoIP Agent version matches or exceeds the patched version listed in Teradici advisory.📡 Detection & Monitoring
Log Indicators:
- PCoIP Agent service crash events
- Unexpected service termination logs
- Null pointer exception in application logs
Network Indicators:
- Multiple connection attempts to PCoIP port 4172 from single source
- Malformed PCoIP protocol packets
SIEM Query:
source="pcoip-agent" AND (event_type="crash" OR event_type="termination")