CVE-2008-6441 in Unreal engine
Summary
by MITRE
Format string vulnerability in the Epic Games Unreal engine client, as used in multiple games, allows remote servers to execute arbitrary code via (1) the CLASS parameter in a DLMGR command, (2) a malformed package (PKG), and possibly (3) the LEVEL parameter in a WELCOME command.
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Analysis
by VulDB Data Team • 12/08/2017
The CVE-2008-6441 vulnerability represents a critical format string vulnerability within the Epic Games Unreal engine client implementation that affects numerous popular gaming titles. This vulnerability stems from improper input validation and handling of user-supplied data within the engine's network communication protocols, creating a pathway for remote code execution attacks. The flaw exists in how the Unreal engine processes specific command parameters and package structures during client-server interactions, making it particularly dangerous in multiplayer gaming environments where trust is placed in remote servers.
The technical exploitation occurs through three primary vectors that leverage format string vulnerabilities in different parts of the Unreal engine's networking stack. The first vector involves the CLASS parameter within the DLMGR command, where malicious servers can craft specially formatted strings that, when processed by the vulnerable client, lead to arbitrary code execution. The second vector targets malformed package files with the PKG extension, where the engine fails to properly validate package headers and content before processing them, allowing attackers to inject malicious format specifiers. The third vector operates through the LEVEL parameter in the WELCOME command, where similar format string handling issues exist. These vulnerabilities are classified under CWE-134 as "Use of Externally-Controlled Format String" which directly maps to the core issue of untrusted data being used as format strings without proper sanitization.
The operational impact of this vulnerability extends far beyond simple game exploitation, as it enables attackers to execute arbitrary code on vulnerable client systems with the privileges of the running game process. This creates a significant risk for players who may unknowingly connect to malicious servers or encounter corrupted game packages. The vulnerability affects multiple games built on the Unreal engine including titles like Unreal Tournament 2004, Unreal Tournament 3, and various other games that utilize the Epic Games engine. Attackers can leverage this vulnerability to install malware, steal player credentials, or use compromised systems as part of botnets for further attacks. The attack surface is particularly concerning in the gaming industry where players frequently connect to third-party servers and download user-generated content, making the exploitation vectors quite accessible.
Mitigation strategies for CVE-2008-6441 require both immediate patching and operational security measures. The primary solution involves applying official patches from Epic Games that address the format string vulnerabilities in the affected engine versions. Organizations and players should ensure all game clients are updated to versions that properly validate and sanitize all user-supplied input before processing it as format strings. Network-level mitigations include implementing strict server authentication mechanisms and avoiding connections to untrusted servers, while also monitoring for unusual package files or command parameters. From an ATT&CK perspective, this vulnerability maps to techniques involving command and control through gaming environments and privilege escalation through client-side exploitation, making it particularly relevant for cybersecurity teams monitoring gaming infrastructure. System administrators should also implement network segmentation and access controls to limit potential lateral movement if exploitation occurs, as the vulnerability could potentially be used as a foothold for broader network compromise.