CVE-2008-5301 in Dovecot
Summary
by MITRE
Directory traversal vulnerability in the ManageSieve implementation in Dovecot 1.0.15, 1.1, and 1.2 allows remote attackers to read and modify arbitrary .sieve files via a ".." (dot dot) in a script name.
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Analysis
by VulDB Data Team • 08/22/2019
The directory traversal vulnerability identified in CVE-2008-5301 represents a critical security flaw within the ManageSieve protocol implementation of Dovecot email server software. This vulnerability affects versions 1.0.15, 1.1, and 1.2 of the Dovecot suite, specifically targeting the Sieve script management functionality that enables users to create automated email filtering rules. The flaw stems from inadequate input validation within the script name handling mechanism, allowing malicious actors to exploit the system through crafted directory traversal sequences.
The technical implementation of this vulnerability occurs when the ManageSieve service processes script names containing ".." sequences that should be properly sanitized and validated. When users submit sieve script names containing directory traversal sequences such as "../" or similar patterns, the system fails to adequately sanitize these inputs before processing them against the file system. This allows attackers to navigate beyond the intended script storage directories and access arbitrary files on the system. The vulnerability operates at the file system level where the application does not properly validate or canonicalize the script names before performing file operations, creating an opportunity for path traversal attacks.
The operational impact of this vulnerability extends beyond simple information disclosure, as it enables both read and write access to arbitrary .sieve files within the system. Attackers can leverage this weakness to read sensitive sieve configuration files that may contain user-specific filtering rules, potentially exposing personal email filtering logic and user preferences. More critically, the ability to modify arbitrary sieve files allows for persistent backdoor establishment, where attackers can inject malicious sieve scripts that execute automated actions such as forwarding emails, deleting messages, or creating unauthorized access points. This represents a significant compromise of email server integrity and user privacy, as the vulnerability affects the core email filtering infrastructure that users trust for automated message handling.
The vulnerability aligns with CWE-22, which specifically addresses directory traversal or path traversal issues in software systems. From an adversarial perspective, this weakness maps directly to ATT&CK technique T1059.007 for scripting and T1566.001 for spearphishing with attachments, as attackers can exploit the vulnerability to upload malicious sieve scripts that automatically execute when email filters are processed. The attack surface is particularly concerning in multi-tenant email environments where a single compromised account could potentially access or modify sieve scripts belonging to other users, creating cross-user privilege escalation opportunities.
Mitigation strategies for this vulnerability require immediate patching of affected Dovecot versions to the latest secure releases that properly implement input validation and canonicalization of script names. Organizations should implement strict input validation at multiple layers, including application-level sanitization of script names, file system access controls, and proper path normalization routines. Network segmentation and monitoring should be implemented to detect anomalous script name patterns, while regular security audits should verify that sieve script storage directories maintain appropriate permissions and access controls. Additionally, implementing principle of least privilege for sieve script management and disabling unnecessary sieve script upload capabilities where possible would significantly reduce the attack surface for this and similar vulnerabilities.