CVE-2007-4754 in Alien Arena 2007
Summary
by MITRE
Format string vulnerability in the safe_bprintf function in acesrc/acebot_cmds.c in Alien Arena 2007 6.10 and earlier allows remote attackers to cause a denial of service (daemon crash) via format string specifiers in a nickname.
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Analysis
by VulDB Data Team • 01/19/2025
The vulnerability identified as CVE-2007-4754 represents a critical format string flaw within the Alien Arena 2007 game server software, specifically within the safe_bprintf function located in the acesrc/acebot_cmds.c source file. This issue affects versions 6.10 and earlier of the popular first-person shooter game, creating a significant security risk that can be exploited by remote attackers to disrupt server operations. The flaw manifests when the game server processes user nicknames containing malicious format string specifiers, which are then improperly handled by the vulnerable function. This particular vulnerability falls under the CWE-134 category of Format String Vulnerability, which is classified as a weakness in software design that allows attackers to manipulate how formatted strings are processed. The vulnerability operates at the application level within the game daemon, making it particularly dangerous as it can be triggered without requiring any special privileges or authentication from the attacker.
The technical exploitation of this vulnerability occurs when a remote attacker crafts a nickname containing format string specifiers such as %s, %d, or other format directives that the safe_bprintf function fails to properly sanitize or validate. When the game server attempts to process this malformed nickname, the function interprets these specifiers as instructions for formatting output rather than literal characters, leading to unpredictable behavior in memory access patterns. This misinterpretation can cause the server daemon to read from or write to arbitrary memory locations, ultimately resulting in a segmentation fault or crash that terminates the game server process. The vulnerability is particularly concerning because it can be triggered through normal game interactions where players change their nicknames, making it an easy target for denial of service attacks that can disrupt gameplay for all connected users. The ATT&CK framework categorizes this type of vulnerability under the T1499.004 technique for Network Denial of Service, as it specifically targets the availability of network services through application-level exploitation.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged to create persistent denial of service conditions that may require manual intervention to resolve. When exploited successfully, the vulnerability forces the game server to crash and restart, potentially causing data loss for ongoing matches and disrupting the gaming experience for all players. The crash typically occurs during the processing of player nicknames, which are commonly changed during gameplay, making this vulnerability particularly effective as an attack vector. Game administrators and server operators must be aware that this vulnerability can be exploited by anyone with network access to the server, as no authentication is required to trigger the flaw. The vulnerability also represents a significant risk to game integrity and player experience, as attackers can repeatedly crash servers to prevent legitimate players from accessing the game service. Furthermore, the fact that this vulnerability exists in a widely used game server implementation means that numerous game servers may be vulnerable to similar attacks, creating a broader impact across the gaming community.
Mitigation strategies for CVE-2007-4754 should focus on both immediate remediation and long-term architectural improvements to prevent similar vulnerabilities from occurring in the future. The most direct solution involves updating to a patched version of Alien Arena 2007 that properly sanitizes user input before processing it through the safe_bprintf function, ensuring that format string specifiers are treated as literal characters rather than formatting instructions. Server administrators should implement input validation measures that strip or escape format specifiers from user-generated content, particularly in nickname fields where such data is processed. The implementation of proper bounds checking and secure string handling practices can prevent the vulnerability from being exploited, as outlined in the secure coding guidelines for preventing format string vulnerabilities. Additionally, network-level protections such as rate limiting for nickname changes and monitoring for unusual patterns of server crashes can help detect and prevent exploitation attempts. Organizations should also consider implementing intrusion detection systems that can identify malicious nickname patterns and automatically block suspicious connections. Regular security audits and code reviews focusing on input validation and string handling functions can help identify similar vulnerabilities in other parts of the application, ensuring comprehensive protection against format string attacks. The vulnerability serves as a reminder of the importance of following secure coding practices and maintaining up-to-date software versions to protect against known exploitation techniques.