CVE-2008-5312 in mailscanner
Summary
by MITRE
mailscanner 4.55.10 and other versions before 4.74.16-1 might allow local users to overwrite arbitrary files via a symlink attack on certain temporary files used by the (1) f-prot-autoupdate, (2) clamav-autoupdate, (3) panda-autoupdate.new, (4) trend-autoupdate.new, and (5) rav-autoupdate.new scripts in /etc/MailScanner/autoupdate/, a different vulnerability than CVE-2008-5140.
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Analysis
by VulDB Data Team • 10/19/2018
The vulnerability described in CVE-2008-5312 represents a critical local privilege escalation risk within the MailScanner email security suite version 4.55.10 and earlier. This flaw stems from insecure temporary file handling practices in multiple autoupdate scripts that are responsible for maintaining antivirus definitions and security updates. The vulnerability specifically affects the f-prot-autoupdate, clamav-autoupdate, panda-autoupdate.new, trend-autoupdate.new, and rav-autoupdate.new scripts located in the /etc/MailScanner/autoupdate/ directory. These scripts are designed to automatically download and install security updates for various antivirus engines, but they fail to properly validate or secure the temporary files they create during this process.
The technical implementation of this vulnerability exploits a classic symlink attack pattern where a local attacker can manipulate the temporary file creation process by creating symbolic links that point to sensitive system files. When the autoupdate scripts execute and attempt to write to what they believe are temporary files, they actually overwrite files specified by the attacker through the symbolic links. This occurs because the scripts do not perform proper validation of temporary file paths or implement secure temporary file creation mechanisms. The vulnerability is categorized under CWE-377 as "Insecure Temporary Files" and demonstrates poor secure coding practices in file handling operations. The attack vector is particularly concerning because it requires only local user access and can potentially allow privilege escalation to the root user or the user running the MailScanner service.
The operational impact of this vulnerability extends beyond simple file overwriting, as it can enable attackers to compromise the integrity of the entire email security infrastructure. An attacker who gains local access to a system running vulnerable MailScanner versions could potentially overwrite critical system files, configuration files, or even executable binaries that would affect the operation of the email server. This could lead to service disruption, data compromise, or further escalation within the network environment. The vulnerability affects a wide range of antivirus update mechanisms within the MailScanner framework, making it particularly dangerous as it could be exploited across multiple security layers simultaneously. Security professionals should note that this vulnerability is distinct from CVE-2008-5140, indicating that multiple related issues exist within the same software ecosystem. The attack scenario typically involves an attacker creating symbolic links in the autoupdate directory before the legitimate scripts run, then waiting for the scripts to execute and overwrite the targeted files through the symbolic link mechanism.
The recommended mitigation strategy involves immediate upgrading to MailScanner version 4.74.16-1 or later, which contains the necessary patches to address the insecure temporary file handling. Organizations should also implement additional security measures such as verifying file permissions and ownership of the autoupdate scripts and directories, monitoring for unauthorized file modifications, and ensuring proper file system permissions are maintained. The ATT&CK framework categorizes this vulnerability under T1059.001 for execution through command and scripting interpreter, and T1548.001 for abuse of sudo privileges, as attackers may attempt to escalate their local privileges through exploitation of this flaw. System administrators should also consider implementing file integrity monitoring solutions to detect unauthorized changes to critical system files and ensure that the MailScanner installation follows security best practices for temporary file handling and privilege management. Additionally, organizations should conduct regular security audits of their email security infrastructure to identify and remediate similar vulnerabilities in other security tools that may be running with elevated privileges.