steam_client

In Valve Steam 1528829181 BETA, it is possible to perform a homograph / homoglyph attack to create fake URLs in the client, which may trick users into visiting unintended web sites.

An issue was discovered in Valve Steam Client 2.10.91.91. The installer allows local users to gain NT AUTHORITYSYSTEM privileges because some parts of %PROGRAMFILES(X86)%Steam and/or %COMMONPROGRAMFILES(X86)%Steam have weak permissions during a critical time window. An attacker can make this time window arbitrarily long by using opportunistic locks.

Valve Steam Client before 2019-09-12 allows placing or appending partially controlled filesystem content, as demonstrated by file modifications on Windows in the context of NT AUTHORITYSYSTEM. This could lead to denial of service, elevation of privilege, or unspecified other impact.

Valve Steam Client for Windows through 2019-08-16 allows privilege escalation (to NT AUTHORITYSYSTEM) because local users can replace the current versions of SteamService.exe and SteamService.dll with older versions that lack the CVE-2019-14743 patch.

Valve Steam Client for Windows through 2019-08-20 has weak folder permissions, leading to privilege escalation (to NT AUTHORITYSYSTEM) via crafted use of CreateMountPoint.exe and SetOpLock.exe to leverage a TOCTOU race condition.

In Valve Steam Client for Windows through 2019-08-07, HKLMSOFTWAREWow6432NodeValveSteam has explicit “Full control” for the Users group, which allows local users to gain NT AUTHORITYSYSTEM access.