CVE-2000-0969 in Half-Life Dedicated Server
Summary
by MITRE
Format string vulnerability in Half Life dedicated server build 3104 and earlier allows remote attackers to execute arbitrary commands by injecting format strings into the changelevel command, via the system console or rcon.
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Analysis
by VulDB Data Team • 04/06/2019
The vulnerability identified as CVE-2000-0969 represents a critical format string vulnerability within the Half Life dedicated server software version 3104 and earlier. This flaw exists in the server's handling of the changelevel command, which is typically used to transition players between different game maps or levels. The vulnerability specifically manifests when the server processes input through the system console or remote console (rcon) interface, creating an attack surface where malicious actors can exploit improper input validation and string formatting operations.
The technical exploitation of this vulnerability occurs through the manipulation of format specifiers within the changelevel command parameters. When the server receives a crafted input string containing format specifiers such as %s, %d, or %x, it fails to properly sanitize or validate these inputs before processing them through standard printf-style functions. This improper handling allows attackers to inject malicious format strings that can lead to memory corruption, stack smashing, or arbitrary code execution. The vulnerability stems from the server's insecure use of variable argument functions without proper input validation, a common pattern that aligns with CWE-134 which specifically addresses the use of untrusted data in format string functions.
The operational impact of this vulnerability extends beyond simple command execution, as it provides remote attackers with the capability to gain full control over the dedicated server instance. Attackers can leverage this vulnerability to execute arbitrary commands with the privileges of the server process, potentially leading to complete system compromise. This allows for unauthorized access to server resources, data exfiltration, modification of game content, or even the installation of persistent backdoors. The remote nature of the attack means that exploitation can occur from any network location without requiring physical access to the server, making it particularly dangerous for online gaming communities and professional gaming infrastructure.
Mitigation strategies for CVE-2000-0969 involve multiple layers of defensive measures that align with established cybersecurity frameworks including the ATT&CK methodology for defensive operations. The primary and most effective mitigation is to upgrade to a patched version of the Half Life dedicated server software that properly validates and sanitizes all user inputs before processing them through format string operations. Additionally, network-level defenses should be implemented including firewall rules that restrict access to the server's rcon and console interfaces to trusted IP addresses only. Input validation mechanisms should be strengthened to reject any input containing format specifiers or other potentially malicious characters. The implementation of intrusion detection systems that monitor for suspicious command patterns and the deployment of network segmentation can further reduce the attack surface. Organizations should also consider implementing application-level firewalls or web application firewalls that can detect and block malicious format string injection attempts, particularly when dealing with legacy gaming infrastructure that may not receive regular security updates.