CVE-2004-1182 in HylaFAX
Summary
by MITRE
hfaxd in HylaFAX before 4.2.1, when installed with a "weak" hosts.hfaxd file, allows remote attackers to authenticate and bypass intended access restrictions via a crafted (1) username or (2) hostname that satisfies a regular expression that is matched against a hosts.hfaxd entry without a password.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 05/29/2019
The vulnerability described in CVE-2004-1182 affects the hfaxd component of HylaFAX software versions prior to 4.2.1, representing a significant authentication bypass flaw that could enable remote attackers to gain unauthorized access to fax services. This issue specifically targets the hosts.hfaxd configuration file which controls access permissions for fax operations, creating a dangerous scenario where improperly configured access controls can be exploited by malicious actors. The vulnerability stems from inadequate validation of authentication credentials, particularly when the hosts.hfaxd file contains entries without explicit password requirements, allowing attackers to craft specific inputs that match regular expression patterns without proper authentication.
The technical flaw manifests in the regular expression matching mechanism used by hfaxd during authentication processes. When the hosts.hfaxd file contains entries that lack explicit password fields, the system's authentication routine fails to properly validate the legitimacy of authentication attempts. Attackers can exploit this weakness by crafting either a specially formatted username or hostname that matches the regular expression pattern defined in the hosts.hfaxd file, thereby bypassing the intended access controls that should require proper authentication credentials. This vulnerability falls under the category of improper input validation and authentication bypass mechanisms, aligning with CWE-285 for improper authorization and CWE-312 for exposure of sensitive information through cleartext transmission. The regular expression matching process becomes a critical weakness where pattern matching occurs without sufficient credential verification, creating a pathway for unauthorized access.
Operationally, this vulnerability poses severe risks to organizations relying on HylaFAX for fax services, as remote attackers can potentially access fax systems without proper authorization, leading to unauthorized fax transmission, data interception, or system compromise. The impact extends beyond simple unauthorized access to include potential data leakage through fax communications, system resource exhaustion through unauthorized usage, and possible escalation to broader network compromise if the fax system has access to sensitive internal resources. Organizations may experience unauthorized fax processing, which could lead to financial loss through fraudulent fax transmissions, privacy violations from unauthorized document access, and potential regulatory compliance issues. The vulnerability's remote exploitability means that attackers do not need physical access to the system, making it particularly dangerous for network-connected fax services. According to ATT&CK framework, this vulnerability maps to T1110.001 for Brute Force and T1078.002 for Valid Accounts, as attackers can leverage crafted credentials to bypass authentication mechanisms and maintain persistent access to fax services.
The recommended mitigations for this vulnerability include immediate upgrading to HylaFAX version 4.2.1 or later, which contains proper authentication validation mechanisms. System administrators should also implement proper configuration of the hosts.hfaxd file by ensuring all entries require explicit authentication credentials and by removing any weak entries that lack proper password requirements. Additional security measures should include network segmentation to limit access to fax services, implementation of firewall rules to restrict access to fax ports, and regular security audits of authentication configurations. The configuration should enforce strong authentication requirements where every hosts.hfaxd entry requires either explicit password authentication or proper access control lists that prevent pattern-matching bypasses. Organizations should also implement monitoring for unusual fax activity patterns that could indicate exploitation attempts, and consider implementing multi-factor authentication for critical fax services to provide additional security layers beyond simple username and password authentication.