CVE-2008-4938 in aegis
Summary
by MITRE
aegis 4.24 and aegis-web 4.24 allow local users to overwrite arbitrary files via a symlink attack on (a) /tmp/#####, (b) /tmp/#####.intro, (c) /tmp/aegis.#####.ae, (d) /tmp/aegis.#####, (e) /tmp/aegis.#####.1, (f) /tmp/aegis.#####.2, (g) /tmp/aegis.#####.log, and (h) /tmp/aegis.#####.out temporary files, related to the (1) bng_dvlpd.sh, (2) bng_rvwd.sh, (3) awt_dvlp.sh, (4) awt_intgrtn.sh, and (5) aegis.cgi scripts.
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Analysis
by VulDB Data Team • 10/13/2018
The vulnerability described in CVE-2008-4938 represents a critical symlink attack flaw affecting Aegis version 4.24 and Aegis-Web version 4.24. This security weakness stems from improper handling of temporary files during script execution, creating opportunities for local attackers to manipulate the system through symbolic link manipulation. The vulnerability specifically targets multiple temporary file locations within the /tmp directory, each with distinct naming patterns that correspond to different Aegis development and review processes.
The technical flaw manifests when the affected Aegis scripts execute without proper validation of temporary file existence or ownership before writing to these predetermined locations. Attackers can create malicious symbolic links in the /tmp directory that point to critical system files or configuration resources, then trigger the vulnerable scripts to overwrite these targets with arbitrary content. This creates a privilege escalation scenario where local users can modify files they would normally not have write access to, potentially compromising system integrity and confidentiality. The vulnerability impacts several key Aegis development workflows including bng_dvlpd.sh for development, bng_rvwd.sh for review processes, awt_dvlp.sh for development tasks, awt_intgrtn.sh for integration activities, and aegis.cgi for web-based operations.
The operational impact of this vulnerability extends beyond simple file overwriting, as it enables attackers to compromise the integrity of the entire Aegis development environment. By manipulating temporary files used in development and review processes, attackers could potentially inject malicious code into source files, modify build configurations, or corrupt critical development artifacts. This represents a significant risk to software development security, particularly in environments where Aegis is used for managing source code and development workflows. The vulnerability aligns with CWE-377 - Insecure Temporary Files, which specifically addresses the risks associated with improper temporary file handling in security contexts. The attack vector follows patterns consistent with the ATT&CK technique T1059.007 - Command and Scripting Interpreter: Unix Shell, as exploitation requires triggering the vulnerable scripts through shell execution.
Mitigation strategies should focus on implementing proper temporary file handling practices, including using secure temporary file creation methods that prevent symlink attacks, implementing proper file ownership checks, and utilizing atomic file operations. System administrators should also consider restricting write access to the /tmp directory for non-privileged users and implementing monitoring for suspicious symlink creation patterns. The recommended approach involves modifying the vulnerable scripts to use secure temporary file creation functions that ensure atomic creation of temporary files without symbolic link vulnerabilities, aligning with industry best practices for secure coding and system hardening as outlined in various security frameworks and standards.