CVE-2005-3538 in HylaFAX
Summary
by MITRE
hfaxd in HylaFAX 4.2.3, when PAM support is disabled, accepts arbitrary passwords, which allows remote attackers to gain privileges.
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Analysis
by VulDB Data Team • 06/13/2019
The vulnerability identified as CVE-2005-3538 affects the hfaxd component of HylaFAX version 4.2.3, specifically when the Pluggable Authentication Module support is disabled. This represents a critical authentication flaw that undermines the security model of the fax server software. The issue stems from the software's handling of user credentials when PAM authentication is not available, creating an exploitable condition that can be leveraged by remote threat actors.
The technical flaw manifests in the authentication mechanism where hfaxd fails to properly validate user passwords when PAM support is disabled. This occurs because the software implements a permissive authentication strategy that accepts any password provided by an attacker, bypassing the normal credential verification process. The vulnerability exists at the authentication layer where the system should enforce password validation but instead grants access regardless of the entered credentials. This behavior creates a privilege escalation vector that allows unauthorized users to gain administrative or user-level access to the fax server.
From an operational perspective, this vulnerability presents significant risks to organizations relying on HylaFAX for their fax infrastructure. Remote attackers can exploit this weakness to gain unauthorized access to fax services, potentially leading to data interception, system compromise, or disruption of fax operations. The impact extends beyond simple unauthorized access as the compromised system could serve as a foothold for further attacks within the network. The vulnerability is particularly concerning because it affects the core authentication functionality of the fax server, making it a prime target for automated exploitation attempts.
The security implications of this vulnerability align with CWE-287, which addresses improper authentication issues in software systems. This weakness allows attackers to bypass authentication mechanisms through the acceptance of arbitrary passwords, representing a fundamental flaw in the security architecture. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques where adversaries exploit weak authentication controls to gain higher-level system access. The vulnerability also relates to initial access vectors where attackers can establish persistent access through compromised authentication mechanisms.
Mitigation strategies for this vulnerability should focus on immediate remediation through software updates to newer versions of HylaFAX that address the authentication flaw. Organizations should also implement network segmentation to limit access to fax services and consider disabling the affected service entirely if it is not critical to operations. Additional security controls such as firewall rules to restrict access to fax services and monitoring for unauthorized authentication attempts should be implemented. The most effective long-term solution involves upgrading to patched versions of HylaFAX and ensuring proper authentication configuration with PAM support enabled to prevent similar issues in the future.