An issue exists in GalaxyClientService.exe in GOG Galaxy (Beta) 2.0.67.2 through 2.0.71.2 that could allow authenticated users to overwrite and corrupt critical system files via a combination of an NTFS Junction and an RPC Object Manager symbolic link and could result in a denial of service.

GOG Galaxy 2.0.0.2 suffers from Missing SSL Certificate Validation. An attacker who controls the local network, DNS, or a proxy can perform a man-in-the-middle (MitM) attack to intercept update requests and replace installer or update packages with malicious files.

An exploitable local privilege escalation vulnerability exists in GOG Galaxy 2.0.46. Due to insufficient folder permissions, an attacker can hijack the %ProgramData%\GOG.com folder structure and change the GalaxyCommunication service executable to a malicious file, resulting in code execution as SYSTEM.

GalaxyClient version 2.0.28.9 loads unsigned DLLs such as zlib1.dll, libgcc_s_dw2-1.dll and libwinpthread-1.dll from PATH, which allows an attacker to potentially run code locally through unsigned DLL loading.

GOG Galaxy GalaxyClientService Privilege Escalation

The GalaxyClientService component of GOG Galaxy runs with elevated SYSTEM privileges in a Windows environment. Due to the software shipping with embedded, static RSA private key, an attacker with this key material and local user permissions can effectively send any operating system command to the service for execution in this elevated context. The service listens for such commands on a locally-bound network port, localhost:9978. A Metasploit module has been published which exploits this vulnerability. This issue affects the 2.0.x branch of the software (2.0.12 and earlier) as well as the 1.2.x branch (1.2.64 and earlier). A fix was issued for the 2.0.x branch of the affected software.

The client (aka GalaxyClientService.exe) in GOG GALAXY through 2.0.41 (as of 12:58 AM Eastern, 9/26/21) allows local privilege escalation from any authenticated user to SYSTEM by instructing the Windows service to execute arbitrary commands. This occurs because the attacker can inject a DLL into GalaxyClient.exe, defeating the TCP-based "trusted client" protection mechanism.

An issue was discovered in GOG Galaxy Client 2.0.17. Local escalation of privileges is possible when a user installs a game or performs a verify/repair operation. The issue exists because of weak file permissions and can be exploited by using opportunistic locks.

An issue was discovered in GOG Galaxy Client 2.0.17. Local escalation of privileges is possible when a user starts or uninstalls a game because of weak file permissions and missing file integrity checks.

In GOG Galaxy 1.2.67, there is a service that is vulnerable to weak file/service permissions: GalaxyClientService.exe. An attacker can put malicious code in a Trojan horse GalaxyClientService.exe. After that, the attacker can re-start this service as an unprivileged user to escalate his/her privileges and run commands on the machine with SYSTEM rights.

An exploitable local privilege escalation vulnerability exists in the GalaxyClientService installed by GOG Galaxy. Due to Improper Access Control, an attacker can send unauthenticated local TCP packets to the service to gain SYSTEM privileges in Windows system where GOG Galaxy software is installed. All GOG Galaxy versions before 1.2.60 and all corresponding versions of GOG Galaxy 2.0 Beta are affected.

An exploitable local denial-of-service vulnerability exists in the privileged helper tool of GOG Galaxy's Games, version 1.2.47 for macOS. An attacker can send malicious data to the root-listening service, causing the application to terminate and become unavailable.

An exploitable local information leak vulnerability exists in the privileged helper tool of GOG Galaxy's Games, version 1.2.47 for macOS. An attacker can pass a PID and receive information running on it that would usually only be accessible to the root user.

An exploitable local privilege escalation vulnerability exists in the privileged helper tool of GOG Galaxy's Games, version 1.2.47 for macOS. An attacker can globally create directories and subdirectories on the root file system, as well as change the permissions of existing directories.

An exploitable local privilege escalation vulnerability exists in the privileged helper tool of GOG Galaxy's Games, version 1.2.47 for macOS. An attacker can globally adjust folder permissions leading to execution of arbitrary code with elevated privileges.

An exploitable local privilege elevation vulnerability exists in the file system permissions of GOG Galaxy's “Games” directory, version 1.2.48.36 (Windows 64-bit Installer). An attacker can overwrite executables of installed games to exploit this vulnerability and execute arbitrary code with elevated privileges.

An exploitable local privilege elevation vulnerability exists in the file system permissions of the `Temp` directory in GOG Galaxy 1.2.48.36 (Windows 64-bit Installer). An attacker can overwrite executables of the Desktop Galaxy Updater to exploit this vulnerability and execute arbitrary code with SYSTEM privileges.

An exploitable local privilege elevation vulnerability exists in the file system permissions of GOG Galaxy's install directory. An attacker can overwrite an executable that is launched as a system service on boot by default to exploit this vulnerability and execute arbitrary code with system privileges.