Valve Steam Client Application v1559/1559 Local Privilege Escalation

Title: Valve Steam Client Application v1559/1559 Local Privilege Escalation
Advisory ID: ZSL-2011-5022
Type: Local
Impact: Privilege Escalation
Risk: (3/5)
Release Date: 29.06.2011
Steam is a digital distribution, digital rights management, multiplayer and communications platform developed by Valve Corporation. It is used to distribute games and related media online, from small independent developers to larger software houses. Steam also has community features, automated game updates, and in-game voice and chat functionality.
Steam is vulnerable to an elevation of privileges vulnerability which can be used by a simple user that can change the executable file with a binary of choice. The vulnerability exist due to the improper permissions, with the "F" flag (Full Control) for the "Users" group, for the binary file Steam.exe, GameOverlayUI.exe and steamerrorreporter.exe. The binary (Steam.exe) is set by default to Startup with "-silent" parameter.
Valve Corporation -
Affected Version
Built: Jun 1, 2011 at 15:31:24
Steam API: v010
Steam package versions 1559 / 1559
File version: 1.0.968.628
Tested On
Microsoft Windows XP Professional SP3 (EN)
Vendor Status
[24.06.2011] Vulnerability discovered.
[25.06.2011] Initial contact with the vendor.
[25.06.2011] Auto-reply from the vendor stating that the message is received.
[28.06.2011] No reply from the vendor.
[29.06.2011] Public security advisory released.
Vulnerability discovered by Gjoko Krstic - <>
[29.06.2011] - Initial release
[30.06.2011] - Added reference [1], [2] and [3]
[01.07.2011] - Added reference [4] and [5]
[02.07.2011] - Added reference [6]
Zero Science Lab