CVE-2004-0881 in getmail
Summary
by MITRE
getmail 4.x before 4.2.0, and other versions before 3.2.5, when run as root, allows local users to write files in arbitrary directories via a symlink attack on subdirectories in the maildir.
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Analysis
by VulDB Data Team • 07/01/2021
The vulnerability described in CVE-2004-0881 represents a significant privilege escalation and arbitrary file writing flaw affecting getmail email retrieval software versions prior to 3.2.5 and 4.2.0. This issue specifically manifests when the getmail application executes with root privileges, creating a dangerous attack surface for local malicious users who can leverage symbolic link manipulation to gain unauthorized file system access. The flaw stems from inadequate directory validation during mail processing operations, particularly when handling subdirectories within the maildir structure.
The technical implementation of this vulnerability involves a classic symlink attack pattern where an attacker crafts malicious symbolic links within the maildir hierarchy before the getmail process can process them. When getmail runs as root and encounters these crafted symlinks, it follows the symbolic links and writes mail files to arbitrary directories specified by the attacker rather than the intended mail storage locations. This behavior directly violates the principle of least privilege and creates an attack vector for privilege escalation. The vulnerability is categorized under CWE-59, which specifically addresses improper handling of symbolic links, making it a well-documented weakness in file system security practices.
The operational impact of this vulnerability extends beyond simple unauthorized file writing, as it enables attackers to potentially overwrite critical system files, inject malicious content into system directories, or establish persistence mechanisms. The attack requires local access and root execution privileges, making it particularly dangerous in multi-user environments where users might have legitimate reasons to run getmail with elevated permissions. This flaw effectively undermines the security model of the mail retrieval system and creates opportunities for attackers to escalate privileges or compromise system integrity. The vulnerability also aligns with ATT&CK technique T1068, which covers local privilege escalation through exploitation of system-level software vulnerabilities.
Mitigation strategies for this vulnerability should focus on immediate patching of affected getmail versions to 3.2.5 or 4.2.0 and later releases where the symbolic link handling has been properly addressed. System administrators should implement strict file system permissions and consider running getmail with reduced privileges whenever possible, avoiding root execution unless absolutely necessary. Additional protective measures include implementing proper directory validation checks, monitoring for unauthorized symbolic link creation in mail directories, and conducting regular security audits of mail processing systems. The fix typically involves ensuring that getmail validates directory contents before processing and refuses to follow symbolic links during mail retrieval operations, thereby preventing the arbitrary file writing behavior that enables the attack.