CVE-2023-40187
📋 TL;DR
This CVE describes a use-after-free vulnerability in FreeRDP's H.264 video codec implementation that could allow remote code execution or denial of service. It affects users running FreeRDP 3.x beta versions for remote desktop connections. Attackers could potentially exploit this to crash the FreeRDP client or execute arbitrary code.
💻 Affected Systems
- FreeRDP
📦 What is this software?
Freerdp by Freerdp
Freerdp by Freerdp
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution allowing complete compromise of the FreeRDP client system, potentially leading to lateral movement in networks.
Likely Case
Application crash (denial of service) disrupting remote desktop sessions, with potential for remote code execution depending on exploit sophistication.
If Mitigated
Limited to denial of service if exploit fails or memory protections prevent code execution.
🎯 Exploit Status
Exploitation requires the attacker to control or compromise an RDP server that the vulnerable client connects to, or trick the user into connecting to a malicious server.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.0.0-beta3 and later
Vendor Advisory: https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-pwf9-v5p9-ch4f
Restart Required: Yes
Instructions:
1. Upgrade FreeRDP to version 3.0.0-beta3 or later. 2. For package managers: Use your distribution's package manager (apt, yum, etc.) to update. 3. For source builds: Download latest from GitHub and rebuild. 4. Restart any FreeRDP applications or services.
🔧 Temporary Workarounds
No known workarounds
allThe vendor advisory states there are no known workarounds for this vulnerability.
🧯 If You Can't Patch
- Switch to FreeRDP 2.x stable releases which are not affected.
- Temporarily disable or restrict RDP connections to untrusted servers using network controls.
🔍 How to Verify
Check if Vulnerable:
Check FreeRDP version: xfreerdp --version or freerdp --version. If output shows 3.x beta version lower than 3.0.0-beta3, system is vulnerable.Check Version:
xfreerdp --version 2>/dev/null || freerdp --version 2>/dev/null || dpkg -l freerdp2 2>/dev/null || rpm -q freerdp 2>/dev/nullVerify Fix Applied:
After update, verify version is 3.0.0-beta3 or higher using xfreerdp --version.📡 Detection & Monitoring
Log Indicators:
- FreeRDP crash logs with segmentation faults in h264.c
- Unexpected process termination of xfreerdp/freerdp processes
Network Indicators:
- RDP connections to unusual or untrusted servers
- Abnormal RDP session disconnections
SIEM Query:
process.name:"xfreerdp" OR process.name:"freerdp" AND (event.type:"crash" OR exit_code:139)🔗 References
- https://github.com/FreeRDP/FreeRDP/blob/5be5553e0da72178a4b94cc1ffbdace9ceb153e5/libfreerdp/codec/h264.c#L413-L427
- https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-pwf9-v5p9-ch4f
- https://security.gentoo.org/glsa/202401-16
- https://github.com/FreeRDP/FreeRDP/blob/5be5553e0da72178a4b94cc1ffbdace9ceb153e5/libfreerdp/codec/h264.c#L413-L427
- https://github.com/FreeRDP/FreeRDP/security/advisories/GHSA-pwf9-v5p9-ch4f
- https://security.gentoo.org/glsa/202401-16
