CVE-2007-5839 in BitchX
Summary
by MITRE
The e_hostname function in commands.c in BitchX 1.1a allows local users to overwrite arbitrary files via a symlink attack on temporary files when using the (1) HOSTNAME or (2) IRCHOST command.
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Analysis
by VulDB Data Team • 03/16/2021
The vulnerability described in CVE-2007-5839 represents a critical file system security flaw within the BitchX IRC client version 1.1a. This issue stems from improper handling of temporary files during the execution of specific commands, creating an exploitable race condition that allows local attackers to manipulate the file system in unintended ways. The vulnerability specifically affects the e_hostname function located in the commands.c source file, which processes user input for HOSTNAME and IRCHOST commands. When these commands are executed, the software creates temporary files without proper security measures, making them susceptible to symbolic link attacks that can redirect file operations to arbitrary locations within the file system.
The technical implementation of this vulnerability exploits a classic race condition scenario where the software creates temporary files with predictable names and insufficient access controls. During command execution, the e_hostname function generates temporary files that are subsequently processed by the application. An attacker can place a symbolic link with the same name as the expected temporary file in the directory where the command executes, effectively causing the application to write data to a location controlled by the attacker rather than the intended target. This type of attack falls under the category of time-of-check to time-of-use vulnerabilities, where the application checks for file existence and permissions at one point in time, but the actual file operations occur later when the attacker has already manipulated the file system. The vulnerability is particularly dangerous because it allows attackers to overwrite any file that the BitchX process has write permissions to, potentially compromising system integrity and enabling privilege escalation attacks.
The operational impact of this vulnerability extends beyond simple file overwriting, as it can be leveraged to compromise the entire system through various attack vectors. Local attackers who can execute commands within the same user context as the BitchX process can use this flaw to modify critical system files, configuration data, or even inject malicious code into the application's execution flow. The vulnerability demonstrates poor secure coding practices related to temporary file handling and privilege management, which aligns with common weakness patterns documented in CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization) and CWE-367 (Time-of-Check to Time-of-Use Race Condition). Attackers can potentially use this vulnerability to escalate privileges, install backdoors, or modify system configuration files that govern network connectivity and user access. The attack requires minimal privileges since it only requires local user access, making it particularly concerning for multi-user systems where the BitchX application might be running with elevated permissions.
Mitigation strategies for this vulnerability must address both the immediate security flaw and broader system hardening measures. The most effective approach involves modifying the BitchX source code to implement proper temporary file handling techniques, including using secure temporary file creation functions that prevent symbolic link attacks and ensure atomic file operations. System administrators should implement proper file system permissions and access controls to limit the impact of such vulnerabilities, while also considering privilege separation techniques that reduce the potential damage from compromised applications. The vulnerability also highlights the importance of following secure coding guidelines and conducting thorough code reviews to identify similar race condition issues in other applications. Organizations should consider implementing monitoring and alerting systems to detect suspicious file system activities that might indicate exploitation attempts. Additionally, regular security updates and patches should be applied to ensure that known vulnerabilities are addressed promptly, as this particular flaw was likely resolved in subsequent versions of the BitchX software. The ATT&CK framework categorizes this type of vulnerability under T1059 (Command and Scripting Interpreter) and T1078 (Valid Accounts) as attackers may use such vulnerabilities to establish persistent access or escalate privileges within compromised systems.