CVE-2007-2838 in GSAMBAD
Summary
by MITRE
The populate_conns function in src/populate_conns.c in GSAMBAD 0.1.4 allows local users to overwrite arbitrary files via a symlink attack on the /tmp/gsambadtmp temporary file.
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Analysis
by VulDB Data Team • 07/21/2019
The vulnerability identified as CVE-2007-2838 resides within the GSAMBAD 0.1.4 software suite, specifically within the populate_conns function located in the src/populate_conns.c source file. This flaw represents a classic race condition vulnerability that exploits insecure temporary file handling practices, creating a path for local privilege escalation through symbolic link manipulation. The issue manifests when the application creates temporary files in the /tmp directory without proper security measures to prevent symlink attacks, allowing malicious users to manipulate the file system during the temporary file creation process.
The technical exploitation of this vulnerability occurs through a time-of-check to time-of-use (TOCTOU) race condition pattern where the application first checks for the existence of a temporary file and then uses it without revalidating the file system state. During the brief window between the file existence check and the actual file usage, a local attacker can create a symbolic link with the same name as the temporary file, pointing to a target file of their choice. When the application subsequently opens and writes to what it believes is the temporary file, it actually overwrites the target file specified in the symbolic link, potentially leading to arbitrary file modification or privilege escalation depending on the target file's permissions and ownership.
This vulnerability directly maps to CWE-367, which describes Time-of-Check to Time-of-Use (TOCTOU) race conditions, and represents a significant security weakness in the application's temporary file handling methodology. The operational impact extends beyond simple file overwrites, as attackers can potentially target system-critical files, configuration files, or even files owned by privileged users, depending on the execution context of the GSAMBAD application. The vulnerability affects local users who can leverage this flaw to gain unauthorized access to modify files they normally wouldn't have permission to alter, effectively bypassing standard file system access controls and creating potential pathways for privilege escalation.
The attack vector requires local system access and knowledge of the application's temporary file naming conventions, making it particularly dangerous in environments where unprivileged users have access to execute the vulnerable software. Mitigation strategies should focus on eliminating the race condition through proper temporary file creation practices such as using secure temporary file creation functions that provide atomic file creation with appropriate permissions, or implementing proper file descriptor management to prevent symbolic link traversal. Organizations should also consider implementing mandatory access controls, file system permissions tightening, and regular security auditing of temporary file handling mechanisms to prevent similar vulnerabilities from being exploited in other software components. The vulnerability underscores the importance of following secure coding practices as outlined in the OWASP Secure Coding Practices and aligns with ATT&CK technique T1059.007 for privilege escalation through file system manipulation, making it a critical concern for system administrators and security professionals responsible for maintaining the integrity of local file systems and application security controls.