CVE-2002-1392 in mgetty
Summary
by MITRE
faxspool in mgetty before 1.1.29 uses a world-writable spool directory for outgoing faxes, which allows local users to modify fax transmission privileges.
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Analysis
by VulDB Data Team • 07/19/2019
The vulnerability identified as CVE-2002-1392 affects the faxspool component within mgetty versions prior to 1.1.29, representing a critical security flaw in Unix-based systems that handle fax communications. This issue stems from improper directory permissions where the fax spool directory is configured with world-writable permissions, creating an exploitable condition that undermines the integrity of fax transmission controls. The flaw specifically targets the local user threat model, where malicious users with system access can manipulate fax privileges without requiring elevated administrative credentials.
The technical root cause of this vulnerability lies in the improper implementation of file system permissions within the fax spooling mechanism. When mgetty creates its spool directory for managing outgoing fax transmissions, it fails to establish appropriate access controls that would normally restrict write permissions to only authorized processes or users. This configuration allows any local user to modify files within the spool directory, potentially altering fax transmission parameters, redirecting transmissions to unauthorized recipients, or even inserting malicious content into the fax queue. The vulnerability maps directly to CWE-732, which describes improper limitation of a pathname to a restricted directory, and represents a classic example of insufficient access control implementation.
From an operational perspective, this vulnerability creates significant risks for organizations relying on fax communication systems, particularly in environments where multiple users share the same system or where security boundaries are not properly enforced. Local users can exploit this weakness to escalate their privileges within the fax system, potentially gaining unauthorized access to sensitive information transmitted via fax or disrupting legitimate fax communications. The impact extends beyond simple privilege escalation as it can lead to data integrity compromise, unauthorized information disclosure, and potential system availability issues. This vulnerability particularly affects systems where fax services are used for business-critical communications such as financial transactions, medical records, or legal documentation.
The exploitation of this vulnerability aligns with several ATT&CK techniques including privilege escalation through access token manipulation and persistence via modification of system services. Attackers can leverage this weakness to establish persistent access to fax transmission capabilities, potentially creating backdoor mechanisms for future unauthorized access. Organizations should implement immediate mitigations including updating to mgetty version 1.1.29 or later, manually configuring proper directory permissions, and conducting thorough security audits of fax-related services. Additional protective measures include implementing proper user access controls, monitoring fax spool directory modifications, and establishing network segmentation to limit local user access to fax systems where possible. The vulnerability demonstrates the critical importance of proper file system permission management and access control implementation in preventing local privilege escalation attacks that can compromise system integrity and confidentiality.