CVE-2020-7951
📋 TL;DR
CVE-2020-7951 is a memory corruption vulnerability in Valve Dota 2's meshsystem.dll that allows remote attackers to execute arbitrary code or cause denial of service. Attackers can exploit this by creating a malicious gaming server and inviting victims to join. All Dota 2 players running vulnerable versions are affected.
💻 Affected Systems
- Valve Dota 2
📦 What is this software?
Dota 2 by Valvesoftware
⚠️ Risk & Real-World Impact
Worst Case
Full remote code execution on victim's system, allowing complete system compromise, data theft, and persistent backdoor installation.
Likely Case
Game crashes and denial of service, with potential for limited code execution depending on exploit sophistication.
If Mitigated
Game instability or crashes without system compromise if exploit fails or is detected.
🎯 Exploit Status
Exploit requires creating a malicious game server and social engineering victims to join. Public proof-of-concept code exists in GitHub repositories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 7.23e and later
Vendor Advisory: https://store.steampowered.com/news/app/570/view/1696051947026654256
Restart Required: Yes
Instructions:
1. Launch Steam client. 2. Ensure Dota 2 updates automatically (default setting). 3. Verify game version is 7.23e or newer. 4. Restart game if already running.
🔧 Temporary Workarounds
Avoid Unknown Game Servers
allOnly join trusted game servers from known sources. Do not accept invites from unknown players.
Network Segmentation
allBlock Dota 2 game server connections at firewall for sensitive systems.
🧯 If You Can't Patch
- Disable Dota 2 on affected systems until patched
- Implement strict network controls to block connections to unofficial game servers
🔍 How to Verify
Check if Vulnerable:
Check Dota 2 game version in Steam library or in-game settings. If version is earlier than 7.23e, system is vulnerable.Check Version:
In Dota 2 main menu, check bottom-right corner for version number, or in Steam library right-click Dota 2 → Properties → UpdatesVerify Fix Applied:
Confirm game version is 7.23e or newer. Test connecting to various game servers to ensure stability.📡 Detection & Monitoring
Log Indicators:
- Game crash logs with meshsystem.dll errors
- Unexpected game process termination
- Memory access violation errors in game logs
Network Indicators:
- Connections to unfamiliar game server IPs on Dota 2 ports (typically 27015-27030)
- Unusual network traffic patterns during game sessions
SIEM Query:
source="dota2_logs" AND ("meshsystem" OR "memory corruption" OR "access violation")