CVE-2007-4644 in Doomsday
Summary
by MITRE
Format string vulnerability in the Cl_GetPackets function in cl_main.c in the client in Doomsday (aka deng) 1.9.0-beta5.1 and earlier allows remote Doomsday servers to execute arbitrary code via format string specifiers in a PSV_CONSOLE_TEXT message.
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Analysis
by VulDB Data Team • 08/05/2019
The vulnerability identified as CVE-2007-4644 represents a critical format string vulnerability within the Doomsday engine client component known as deng version 1.9.0-beta5.1 and earlier. This flaw exists in the Cl_GetPackets function located in the cl_main.c source file, which handles packet processing from remote servers. The vulnerability specifically manifests when processing PSV_CONSOLE_TEXT messages that are transmitted from remote Doomsday servers to client instances. This type of vulnerability falls under the Common Weakness Enumeration category CWE-134 which describes weaknesses related to format string vulnerabilities where untrusted data is used as format string arguments without proper validation or sanitization. The security implications are severe as this vulnerability can be exploited by remote attackers who control the server side, making it particularly dangerous in networked gaming environments where clients connect to untrusted servers.
The technical exploitation of this vulnerability occurs through careful crafting of format string specifiers within the PSV_CONSOLE_TEXT message payload. When the client processes this message through the vulnerable Cl_GetPackets function, the format string parameters are interpreted directly without proper sanitization, allowing attackers to manipulate memory contents and potentially execute arbitrary code on the victim's machine. This type of attack leverages the fundamental flaw in how printf-style functions handle format specifiers when user-supplied data is used as the format string argument. The attacker can exploit this by injecting format specifiers such as %x, %s, %n, or other format specifiers that can read from memory locations or write to memory addresses, ultimately leading to code execution. The attack vector specifically targets the client-side processing of console text messages, which are typically used for displaying server status information, chat messages, or other console output to players. This vulnerability demonstrates the classic characteristics of format string attacks that are documented in the MITRE ATT&CK framework under the technique of command and control through the use of format string exploitation to achieve remote code execution.
The operational impact of CVE-2007-4644 extends beyond simple code execution to encompass complete system compromise of vulnerable Doomsday client installations. When exploited successfully, this vulnerability allows remote attackers to gain arbitrary code execution privileges on the target system, potentially leading to full system compromise including privilege escalation, data exfiltration, or the installation of persistent backdoors. The vulnerability affects all versions of the Doomsday engine client up to and including version 1.9.0-beta5.1, making it particularly concerning for users who have not updated their installations. The attack requires minimal privileges from the attacker side as they only need to control a remote Doomsday server to deliver the malicious payload, making it a particularly dangerous vulnerability for multiplayer gaming environments where users connect to potentially malicious servers. The vulnerability also impacts the integrity and availability of the gaming experience, as users may be unable to connect to servers or may experience crashes and system instability when exploited. Organizations and individuals using the Doomsday engine for gaming or development should immediately implement mitigations to prevent exploitation, as the vulnerability provides a direct path to system compromise without requiring any local privileges or user interaction beyond connecting to an affected server. The vulnerability underscores the importance of input validation and proper sanitization of all user-supplied data in networked applications, particularly those handling real-time communication protocols and console text processing functions.