CVE-2007-5713 in Half-Life Dedicated Server
Summary
by MITRE
Off-by-one error in the GeoIP module in the AMX Mod X 1.76d plugin for Half-Life Server might allow attackers to execute arbitrary code or cause a denial of service via unspecified input related to geolocation, which triggers an error message from the (1) geoip_code2 or (2) geoip_code3 function, leading to a buffer overflow.
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Analysis
by VulDB Data Team • 10/30/2017
The vulnerability identified as CVE-2007-5713 represents a critical off-by-one error within the GeoIP module of AMX Mod X 1.76d plugin for Half-Life Server environments. This flaw exists in the handling of geolocation data processing and manifests specifically within the geoip_code2 and geoip_code3 functions. The vulnerability stems from improper boundary checking mechanisms that fail to validate input lengths against allocated buffer sizes, creating a condition where attackers can manipulate the input data to exceed the intended buffer limits. The issue falls under the category of buffer overflow vulnerabilities, which are particularly dangerous as they can lead to arbitrary code execution or system instability.
The technical implementation of this vulnerability involves the GeoIP module's failure to properly sanitize geolocation data inputs before processing them through the affected functions. When legitimate or malicious input is passed to geoip_code2 or geoip_code3, the module does not adequately verify that the input length matches the expected buffer capacity. This discrepancy allows attackers to craft inputs that, when processed, cause the program to write beyond the allocated memory boundaries. The off-by-one error specifically indicates that the validation logic checks boundaries incorrectly, typically by using <= instead of < or similar boundary condition flaws that result in one extra byte being written beyond the intended limit.
From an operational perspective, this vulnerability presents significant risks to Half-Life server environments that utilize the AMX Mod X plugin with GeoIP functionality enabled. Attackers can exploit this weakness to either execute arbitrary code on the target server, potentially gaining full control over the gaming environment, or to cause a denial of service condition that disrupts legitimate gameplay for users. The impact extends beyond simple service disruption as the potential for remote code execution means that attackers could install backdoors, exfiltrate server data, or compromise the entire gaming infrastructure. The vulnerability affects servers running the specific AMX Mod X version 1.76d and any system that relies on the GeoIP module for location-based features.
The vulnerability's classification aligns with CWE-121, which addresses stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios. From an adversary tactics perspective, this flaw maps to ATT&CK technique T1059.007 for command and script injection, and T1499.004 for network denial of service. The exploitation requires minimal privileges and can be automated, making it particularly attractive to malicious actors. The vulnerability's exploitation is facilitated by the fact that it occurs during normal geolocation processing, meaning legitimate server operations are not immediately disrupted, allowing attackers to maintain persistence. Security professionals should consider this vulnerability in the context of the broader attack surface for gaming servers, where such modules often provide extended functionality that may not be properly secured against adversarial input manipulation.
Mitigation strategies should include immediate patching of the AMX Mod X plugin to version 1.76e or later, which contains the necessary boundary checking fixes. Administrators should also implement network-level restrictions to limit geolocation data sources to trusted inputs and consider disabling GeoIP functionality if not essential for server operations. Input validation mechanisms should be strengthened to include comprehensive boundary checks and length validation before any geolocation data is processed. Additionally, server monitoring should be enhanced to detect unusual patterns in geolocation data processing that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper input validation in server-side applications and highlights the need for comprehensive security testing of plugin modules that extend core server functionality.