CVE-2002-1782 in uw-imap
Summary
by MITRE
The default configuration of University of Washington IMAP daemon (wu-imapd), when running on a system that does not allow shell access, allows a local user with a valid IMAP account to read arbitrary files as that user.
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Analysis
by VulDB Data Team • 05/21/2019
The vulnerability identified as CVE-2002-1782 affects the University of Washington IMAP daemon implementation known as wu-imapd, representing a critical security flaw in email server software that has persisted for over two decades. This vulnerability specifically manifests in the default configuration settings of the IMAP daemon when deployed on systems where shell access is restricted, creating an exploitable condition that undermines the fundamental security assumptions of the system. The flaw resides in how the daemon handles file access permissions and path resolution when processing IMAP commands, allowing unauthorized file reading operations that should normally be restricted to system administrators or authorized users.
The technical nature of this vulnerability stems from inadequate input validation and improper privilege separation within the IMAP daemon's file access mechanisms. When a local user with a valid IMAP account connects to the system, the daemon fails to properly sanitize file paths or enforce appropriate access controls, enabling the attacker to construct malicious IMAP commands that traverse the file system and read files that would normally be protected. This represents a classic privilege escalation vulnerability where a user with limited access can leverage the IMAP service to gain unauthorized access to sensitive system files, configuration data, or user information that exists outside the normal scope of their IMAP account permissions. The vulnerability operates under CWE-22 which classifies improper limitation of a pathname to a restricted directory, commonly known as path traversal attacks.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable attackers to access critical system files including password hashes, configuration settings, and other sensitive data that could facilitate further attacks. Attackers can exploit this condition to read system files such as /etc/passwd, /etc/shadow, or application-specific configuration files that may contain database credentials, API keys, or other valuable information. The vulnerability is particularly dangerous in environments where the IMAP daemon runs with elevated privileges or where sensitive data is stored in predictable locations accessible through the IMAP service. This flaw can be exploited as part of a broader attack chain to establish persistence, escalate privileges, or gather intelligence for subsequent phases of compromise.
Mitigation strategies for this vulnerability require immediate attention from system administrators and security teams responsible for maintaining email infrastructure. The most effective immediate solution involves modifying the wu-imapd configuration to disable or restrict file reading capabilities, particularly when shell access is not available on the system. Administrators should implement proper input validation and path sanitization within the IMAP daemon configuration to prevent arbitrary file access through IMAP commands. The recommended approach includes updating the daemon to a patched version or applying configuration changes that enforce strict file access controls, ensuring that the IMAP service operates with minimal necessary privileges and that all file paths are properly validated before processing. This vulnerability also highlights the importance of following the principle of least privilege and implementing proper security hardening measures for network services, aligning with ATT&CK technique T1078 which addresses valid accounts and privilege escalation through service access. Organizations should conduct comprehensive security audits of their email infrastructure and ensure that all network services are properly configured to prevent unauthorized file access operations that could compromise system integrity and confidentiality.