CVE-2005-3539 in HylaFAX
Summary
by MITRE
Multiple eval injection vulnerabilities in HylaFAX 4.2.3 and earlier allow remote attackers to execute arbitrary commands via (1) the notify script in HylaFAX 4.2.0 to 4.2.3 and (2) crafted CallID parameters to the faxrcvd script in HylaFAX 4.2.2 and 4.2.3.
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Analysis
by VulDB Data Team • 01/04/2025
The CVE-2005-3539 vulnerability represents a critical security flaw in HylaFAX versions 4.2.3 and earlier, specifically targeting the fax processing and notification mechanisms within the system. This vulnerability stems from improper input validation and sanitization in two distinct components of the HylaFAX suite, creating multiple attack vectors for remote command execution. The affected systems are particularly vulnerable during fax reception and notification processing phases, where the software fails to properly validate user-supplied input before executing system commands. The vulnerability affects the notify script functionality in HylaFAX versions 4.2.0 through 4.2.3 and also impacts the faxrcvd script in versions 4.2.2 and 4.2.3, creating a comprehensive attack surface that spans multiple release versions of the software.
The technical flaw manifests through the use of the eval function in perl scripting within the HylaFAX components, which directly executes user-provided input without proper sanitization or validation. When the notify script processes incoming fax notifications or when the faxrcvd script handles incoming fax data, crafted CallID parameters are passed directly to eval statements, allowing attackers to inject malicious code that gets executed with the privileges of the fax processing daemon. This type of vulnerability falls under CWE-94, which specifically addresses "Improper Control of Generation of Code ('Code Injection')" and represents a classic example of command injection through improper input handling. The eval injection occurs because the software does not properly escape or validate special characters that could alter the intended execution flow of commands, creating opportunities for attackers to manipulate the execution environment through carefully crafted input parameters.
The operational impact of this vulnerability is severe and far-reaching, as it allows remote attackers to execute arbitrary commands on systems running vulnerable HylaFAX versions. Attackers can potentially gain full system control, escalate privileges, or use the compromised system as a launching point for further attacks within the network infrastructure. The vulnerability affects organizations that rely on fax-based communication systems for business operations, including financial institutions, healthcare providers, and government agencies that may transmit sensitive information via fax. The remote nature of the attack means that adversaries do not require physical access or local network presence to exploit the vulnerability, making it particularly dangerous for organizations with public fax servers or those exposed to the internet. According to ATT&CK framework, this vulnerability maps to T1059.007 "Command and Scripting Interpreter: Unix Shell" and T1133 "External Remote Services," as attackers can leverage the compromised fax system to establish persistent access or exfiltrate data.
Organizations affected by CVE-2005-3539 should immediately implement mitigations including upgrading to HylaFAX versions 4.2.4 or later, which contain patches addressing the eval injection vulnerabilities. The most effective remediation approach involves implementing proper input validation and sanitization measures, specifically ensuring that all user-supplied parameters are properly escaped before being processed by any system commands or eval functions. System administrators should also consider implementing network segmentation to limit exposure of fax servers to untrusted networks, while monitoring for suspicious fax activity or unusual command execution patterns. Additionally, organizations should conduct comprehensive security assessments of their fax infrastructure and implement proper access controls to prevent unauthorized modifications to fax processing scripts. The vulnerability highlights the critical importance of secure coding practices, particularly in legacy systems that may not have undergone modern security reviews, and demonstrates the long-term risks associated with maintaining outdated software components in enterprise environments.