CVE-2001-0387 in Hylafax
Summary
by MITRE
Format string vulnerability in hfaxd in HylaFAX before 4.1.b2_2 allows local users to gain privileges via the -q command line argument.
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Analysis
by VulDB Data Team • 04/30/2019
The vulnerability described in CVE-2001-0387 represents a critical format string flaw within the hfaxd component of the HylaFAX fax server software. This issue affects versions prior to 4.1.b2_2 and specifically targets the command line argument processing mechanism. The vulnerability manifests when the fax daemon processes the -q command line argument, which is typically used for specifying queue-related operations within the fax system. This format string vulnerability arises from improper input validation and handling of user-supplied arguments that are subsequently passed to format string functions without proper sanitization.
The technical exploitation of this vulnerability occurs through the manipulation of the -q argument to include format specifiers such as %s, %d, or other format string directives. When the hfaxd process encounters these maliciously crafted arguments, it fails to properly validate or escape the input before passing it to functions like printf or sprintf. This improper handling allows attackers to manipulate the program's memory layout and potentially execute arbitrary code with elevated privileges. The vulnerability is classified as a local privilege escalation issue since it requires local system access to exploit but can result in privilege elevation from regular user to root or system-level access.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a pathway to compromise the entire fax server infrastructure. Since hfaxd typically runs with elevated privileges to manage fax operations and access system resources, successful exploitation could allow attackers to gain complete control over the fax server. This compromise could enable unauthorized access to fax queues, modification of fax transmission parameters, or even complete system takeover. The vulnerability affects organizations relying on HylaFAX for their fax infrastructure, potentially exposing sensitive communications and system resources to unauthorized access.
Security practitioners should consider this vulnerability in relation to CWE-134 which specifically addresses format string vulnerabilities where format strings are constructed from user-controlled data. The attack pattern aligns with ATT&CK technique T1068 which covers 'Exploitation for Privilege Escalation' and T1548.001 which addresses 'Abuse Elevation Control Mechanism'. Organizations should implement immediate mitigations including updating to HylaFAX version 4.1.b2_2 or later, which contains patches addressing the format string vulnerability. Additional protective measures include implementing strict input validation for command line arguments, using secure coding practices that prevent format string injection, and conducting regular security assessments of fax server configurations. System administrators should also consider implementing least privilege principles for fax daemon processes and monitoring for suspicious command line argument usage that might indicate exploitation attempts.