CVE-2019-17180
📋 TL;DR
The Steam Client vulnerability allows attackers to place or append partially controlled files in the filesystem with SYSTEM-level privileges on Windows. This could lead to denial of service, privilege escalation, or other impacts. All Windows users running Steam Client versions before September 12, 2019 are affected.
💻 Affected Systems
- Valve Steam Client
📦 What is this software?
Steam Client by Valvesoftware
⚠️ Risk & Real-World Impact
Worst Case
Full SYSTEM privilege escalation leading to complete system compromise, installation of persistent malware, or destruction of critical system files.
Likely Case
Denial of service through file corruption or privilege escalation to install unauthorized software.
If Mitigated
Limited impact if proper file permissions and application sandboxing are in place.
🎯 Exploit Status
Exploitation requires local access or ability to execute code on the target system. Multiple public reports demonstrate exploitation techniques.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Steam Client update from September 12, 2019
Vendor Advisory: https://store.steampowered.com/news/54236/
Restart Required: Yes
Instructions:
1. Launch Steam client. 2. Steam will auto-update if not disabled. 3. Restart Steam after update completes. 4. Verify version is post-2019-09-12.
🔧 Temporary Workarounds
Disable Steam Auto-Start
windowsPrevent Steam from running automatically at system startup to reduce attack surface.
Open Steam Settings > Interface > Uncheck 'Run Steam when my computer starts'
Run Steam with Limited Privileges
windowsConfigure Steam to run as standard user instead of with elevated privileges.
Right-click Steam shortcut > Properties > Compatibility > Uncheck 'Run this program as an administrator'
🧯 If You Can't Patch
- Uninstall Steam Client from critical systems
- Implement strict application control policies to prevent unauthorized Steam execution
🔍 How to Verify
Check if Vulnerable:
Check Steam client version in Help > About Steam. If version date is before September 12, 2019, system is vulnerable.Check Version:
In Steam client: Help > About SteamVerify Fix Applied:
Verify Steam client has updated to version dated September 12, 2019 or later in Help > About Steam.📡 Detection & Monitoring
Log Indicators:
- Unusual file creation/modification in system directories by Steam process
- Steam.exe accessing privileged file locations
Network Indicators:
- Steam client downloading unusual update packages
- Network traffic from Steam to unexpected destinations
SIEM Query:
Process:steam.exe AND (TargetObject:*\\Windows\\* OR TargetObject:*\\ProgramData\\*)🔗 References
- https://amonitoring.ru/article/steam_vuln_3/
- https://habr.com/ru/company/pm/blog/469507/
- https://hackerone.com/reports/583184
- https://hackerone.com/reports/682774
- https://store.steampowered.com/news/54236/
- https://amonitoring.ru/article/steam_vuln_3/
- https://habr.com/ru/company/pm/blog/469507/
- https://hackerone.com/reports/583184
- https://hackerone.com/reports/682774
- https://store.steampowered.com/news/54236/
