CVE-2010-3095 in Mailscanner
Summary
by MITRE
mailscanner before 4.79.11-2.1 might allow local users to overwrite arbitrary files via a symlink attack on certain temporary files. NOTE: this issue exists because of an incomplete fix for CVE-2008-5313.
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Analysis
by VulDB Data Team • 11/13/2019
The vulnerability described in CVE-2010-3095 represents a significant file system security flaw in the MailScanner email security application that affects versions prior to 4.79.11-2.1. This issue constitutes a symlink attack vulnerability that allows local attackers to potentially overwrite arbitrary files on the system, creating a serious privilege escalation risk. The vulnerability specifically targets temporary files used during the email scanning process, exploiting a race condition that occurs when the application creates and manipulates temporary file references without proper validation of symbolic link integrity.
The technical root cause of this vulnerability stems from inadequate file handling procedures within MailScanner's temporary file creation and management processes. When the application generates temporary files, it fails to properly validate whether the target file path contains symbolic links that could be manipulated by local users. This weakness creates a window where an attacker can establish malicious symbolic links in the temporary file directories before the legitimate application process attempts to create or modify those files. The vulnerability is particularly dangerous because it leverages the principle of least privilege in a way that allows local users to escalate their privileges to potentially overwrite critical system files or configuration data.
This vulnerability directly maps to CWE-377: Insecure Temporary File and CWE-378: Creation of Temporary File With Insecure Permissions, both of which are categorized under the broader category of insecure file handling practices. The attack vector aligns with ATT&CK technique T1059.001 for command and scripting interpreter execution, as attackers can leverage this vulnerability to establish persistent access through overwritten system files. The operational impact is substantial as local users with minimal privileges can potentially compromise the entire email security infrastructure, leading to unauthorized access to email content, potential data exfiltration, and system-wide compromise. The vulnerability also represents a regression issue since it was introduced by an incomplete fix for CVE-2008-5313, indicating that security patches may not have been thoroughly tested for comprehensive coverage of all attack vectors.
The exploitation of this vulnerability requires local system access and involves careful timing to establish the malicious symbolic links before the legitimate application process executes. Attackers typically need to have accounts on the system with basic user privileges to execute this attack successfully. The impact extends beyond simple file overwrites to potentially allow attackers to modify critical system components, install backdoors, or compromise the integrity of the email scanning process itself. Organizations running vulnerable versions of MailScanner should immediately implement the official patch release 4.79.11-2.1, which properly addresses the symlink attack mechanisms by implementing proper file path validation and ensuring that temporary files are created with appropriate permissions and atomic operations. Additionally, system administrators should conduct comprehensive audits of temporary file directories to identify and remove any existing malicious symbolic links that may have been established by attackers.