CVE-2008-4191 in Emacspeak
Summary
by MITRE
extract-table.pl in Emacspeak 26 and 28 allows local users to overwrite arbitrary files via a symlink attack on the extract-table.csv temporary file.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 08/17/2019
The vulnerability identified as CVE-2008-4191 affects Emacspeak versions 26 and 28, specifically within the extract-table.pl script that processes table data extraction. This issue represents a classic symlink attack scenario where local users can exploit improper temporary file handling to overwrite arbitrary files on the system. The vulnerability stems from the script's failure to properly validate or secure temporary file creation processes, creating a path for privilege escalation and potential system compromise.
The technical flaw manifests in the insecure handling of temporary files during the table extraction process. When extract-table.pl executes, it creates a temporary file named extract-table.csv without sufficient security measures to prevent symbolic link attacks. An attacker can create a symbolic link with the same name in the target directory, causing the script to write data to the attacker-controlled location instead of the intended temporary file. This behavior aligns with CWE-377, which addresses insecure temporary file creation practices, and CWE-378, which covers improper temporary file permissions. The vulnerability operates at the file system level and demonstrates poor input validation and inadequate access control mechanisms.
The operational impact of this vulnerability extends beyond simple file overwrites, as it provides local attackers with a means to potentially escalate privileges or compromise system integrity. Since the script likely runs with elevated privileges due to its role in the Emacspeak accessibility suite, an attacker could leverage this weakness to modify critical system files, inject malicious code, or establish persistent access. The attack requires local system access but can be particularly dangerous in multi-user environments where privilege separation is essential. This vulnerability also maps to ATT&CK technique T1059.007 for script execution and T1078 for valid accounts, as it exploits legitimate system accounts to perform unauthorized file operations.
Mitigation strategies for CVE-2008-4191 should focus on implementing proper temporary file handling practices that prevent symbolic link attacks. System administrators should ensure that temporary files are created with unique names, proper permissions, and in secure directories that prevent symlink manipulation. The fix involves modifying the extract-table.pl script to use secure temporary file creation methods such as mkstemp or similar functions that guarantee file uniqueness and prevent symlink race conditions. Additionally, implementing proper file system permissions and access controls around the Emacspeak installation directory can limit the impact of such attacks. Regular security audits and vulnerability assessments should include checks for similar insecure temporary file handling patterns across all system components to prevent similar issues from emerging in other applications.