CVE-2004-2597 in Quake II Server
Summary
by MITRE
Quake II server before R1Q2, as used in multiple products, allows remote attackers to bypass IP-based access control rules via a userinfo string that already contains an "ip" key/value pair but is also long enough to cause a new key/value pair to be truncated, which interferes with the server s ability to find the client s IP address.
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Analysis
by VulDB Data Team • 07/19/2017
The vulnerability described in CVE-2004-2597 represents a significant security flaw in Quake II server implementations that affects multiple products using the R1Q2 server software. This issue stems from improper handling of user information strings during client authentication processes, creating a pathway for malicious actors to circumvent IP-based access controls that are fundamental to network security in multiplayer gaming environments. The vulnerability specifically targets the server's ability to accurately identify client IP addresses, which forms the foundation of access control mechanisms designed to restrict unauthorized network access.
The technical implementation of this vulnerability exploits a buffer management flaw in how the Quake II server processes userinfo strings submitted by clients during connection establishment. When a client connects to the server, it sends a userinfo string containing various key-value pairs including the client's IP address. The server maintains a fixed-size buffer to store these parameters, and when an attacker crafts a userinfo string that already contains an "ip" key-value pair but is sufficiently long to cause truncation of subsequent key-value pairs, the server's IP address resolution mechanism becomes compromised. This occurs because the server's parsing logic cannot properly extract the client's actual IP address from the corrupted userinfo string, leading to incorrect IP-based access control decisions. The flaw operates at the application layer and demonstrates poor input validation and buffer handling practices that are commonly associated with software vulnerabilities classified under CWE-129.
The operational impact of this vulnerability extends beyond simple access control bypass to potentially enable a wide range of malicious activities within the gaming environment. Attackers can exploit this weakness to gain unauthorized access to restricted server features, potentially allowing them to manipulate game state, disrupt gameplay for other users, or even execute arbitrary commands on the server if additional vulnerabilities exist. The vulnerability is particularly concerning in multiplayer gaming contexts where servers often implement strict access controls to prevent cheating, maintain game integrity, and protect against denial-of-service attacks. According to ATT&CK framework concepts, this vulnerability maps to privilege escalation and defense evasion techniques, as attackers can bypass security controls without triggering typical intrusion detection mechanisms. The exploitability of this vulnerability is relatively straightforward, requiring only the ability to connect to the target server and craft a specific userinfo string, making it a common target for automated exploitation tools.
Mitigation strategies for this vulnerability require immediate implementation of server-side input validation and buffer management improvements. System administrators should upgrade to patched versions of the Quake II server software that properly handle userinfo string parsing and prevent truncation attacks. The fix should implement strict bounds checking on all user-provided input, ensure proper handling of key-value pairs regardless of their length, and maintain separate buffers for different types of information to prevent cross-contamination. Additionally, implementing network-level protections such as rate limiting and connection monitoring can help detect and prevent exploitation attempts. Organizations should also consider implementing additional authentication mechanisms beyond IP-based access control, such as client authentication tokens or challenge-response protocols, to provide defense-in-depth against similar vulnerabilities. The vulnerability demonstrates the importance of proper input sanitization and buffer management in security-critical applications, aligning with industry best practices for preventing buffer overflow and injection attacks that are commonly addressed in security frameworks like OWASP Top Ten and NIST cybersecurity guidelines.