CVE-2002-0770 in Quake 2i Server
Summary
by MITRE
Quake 2 (Q2) server 3.20 and 3.21 allows remote attackers to obtain sensitive server cvar variables, obtain directory listings, and execute Q2 server admin commands via a client that does not expand "$" macros, which causes the server to expand the macros and leak the information, as demonstrated using "say $rcon_password."
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Analysis
by VulDB Data Team • 12/26/2024
The vulnerability described in CVE-2002-0770 represents a critical information disclosure flaw in Quake 2 server versions 3.20 and 3.21 that stems from improper handling of variable expansion mechanisms within the game server's command processing pipeline. This vulnerability specifically affects the server's interpretation of dollar sign prefixed variables, commonly known as cvar variables, which are used to store configuration settings and administrative parameters within the Quake 2 engine. The flaw occurs when client connections fail to properly expand these macro variables, creating an exploitable condition where the server itself attempts to expand these variables and inadvertently leaks sensitive information to remote attackers.
The technical execution of this vulnerability relies on a fundamental flaw in the server's input validation and variable expansion logic. When a malicious client sends a specially crafted command containing unexpanded dollar sign variables, the Quake 2 server processes these commands through its internal variable expansion mechanism. This process, which should only occur within controlled contexts, becomes exploitable when the server attempts to expand variables like $rcon_password, which contain sensitive administrative credentials. The server's failure to properly sanitize or validate these expansion requests creates an information leakage channel that can be systematically exploited to extract multiple types of sensitive data including server configuration variables, directory listings, and administrative command parameters. This vulnerability specifically maps to CWE-200, Information Exposure, and CWE-22, Improper Limitation of a Pathname to a Restricted Directory, as it allows unauthorized access to server resources through improper variable handling.
The operational impact of this vulnerability extends beyond simple information disclosure to encompass potential complete server compromise and unauthorized administrative access. Remote attackers can systematically extract sensitive server configuration variables including administrative passwords, server directory structures, and potentially other critical system information that could be used for further exploitation. The ability to execute Q2 server admin commands through this information leakage means that attackers can escalate their privileges and gain full control over the game server. This vulnerability directly aligns with ATT&CK technique T1078, Valid Accounts, and T1083, File and Directory Discovery, as it enables attackers to both obtain valid administrative credentials and discover server file structures. The exploitation process demonstrates a sophisticated understanding of the Quake 2 server's internal mechanics and reveals a fundamental flaw in the server's security model.
Mitigation strategies for this vulnerability require immediate patching of affected Quake 2 server versions to address the variable expansion flaw and implement proper input validation. Administrators should disable unnecessary server features that expose sensitive variables and implement network-level restrictions to limit access to server administrative functions. The most effective approach involves updating to patched versions of Quake 2 server software that properly validate and sanitize variable expansion requests, preventing the server from expanding potentially sensitive variables in response to client input. Additionally, implementing proper access controls and monitoring for suspicious command patterns can help detect exploitation attempts. Network segmentation and firewall rules should be configured to restrict access to server administrative ports and ensure that only trusted clients can send administrative commands. This vulnerability serves as a reminder of the importance of proper input validation and variable handling in server applications, particularly those that process untrusted user input through complex expansion mechanisms.