CVE-2012-2103 in Munin
Summary
by MITRE
The qmailscan plugin for Munin 1.4.5 allows local users to overwrite arbitrary files via a symlink attack on temporary files with predictable names.
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Analysis
by VulDB Data Team • 12/12/2021
The vulnerability identified as CVE-2012-2103 affects the qmailscan plugin within Munin monitoring software version 1.4.5, presenting a significant security risk through a symlink attack mechanism. This flaw specifically targets the plugin's handling of temporary files during the scanning process, where predictable file names create opportunities for local privilege escalation and arbitrary file overwrite attacks. The issue stems from insufficient validation of temporary file creation processes, allowing malicious users to manipulate the system's file operations through symbolic link manipulation.
The technical implementation of this vulnerability involves the qmailscan plugin's failure to properly secure temporary file creation operations. When the plugin executes scanning functions, it generates temporary files with predictable naming conventions that can be anticipated by local attackers. This predictable naming scheme enables attackers to create symbolic links in the expected temporary file locations before the plugin attempts to write to them, thereby redirecting the plugin's file operations to arbitrary targets. The vulnerability operates at the file system level, exploiting the fundamental trust placed in temporary file creation processes without proper atomicity or security checks.
From an operational impact perspective, this vulnerability enables local users to potentially overwrite critical system files, configuration data, or even executable binaries with malicious content. The attack vector requires local system access but does not necessitate network exposure, making it particularly dangerous in multi-user environments where privilege escalation could lead to broader system compromise. The arbitrary file overwrite capability can be leveraged to establish persistent backdoors, modify system configurations, or corrupt essential application data, potentially leading to complete system compromise or denial of service conditions.
The vulnerability aligns with CWE-367, which addresses Time-of-Check to Time-of-Use (TOCTOU) race conditions, and represents a classic example of insecure temporary file handling. This flaw also maps to ATT&CK technique T1059, specifically covering the execution of malicious code through compromised system components, and T1068, which involves local privilege escalation through exploitation of system vulnerabilities. The attack requires minimal privileges and can be executed with standard user access, making it particularly concerning for environments where multiple users share system resources.
Mitigation strategies should focus on implementing proper temporary file handling mechanisms that utilize secure file creation practices such as creating files with unique names and proper permissions, implementing atomic file operations, or using dedicated secure temporary directories with restricted access controls. System administrators should immediately upgrade to patched versions of Munin or apply the appropriate security patches that address the predictable temporary file naming issue. Additionally, implementing proper file system permissions and monitoring for unauthorized symbolic link creation in temporary directories can help detect and prevent exploitation attempts. Regular security audits should verify that temporary file operations follow secure coding practices and that no predictable naming conventions exist in system components.