CVE-2005-3069 in HylaFax
Summary
by MITRE
xferfaxstats in HylaFax 4.2.1 and earlier allows local users to overwrite arbitrary files via a symlink attack on the xferfax$$ temporary file.
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Analysis
by VulDB Data Team • 06/10/2019
The vulnerability described in CVE-2005-3069 affects the xferfaxstats component within HylaFax version 4.2.1 and earlier installations, representing a significant security flaw that enables local attackers to manipulate file system operations through symbolic link manipulation. This issue stems from improper handling of temporary files during fax transfer statistics processing, creating an exploitable race condition that can be leveraged for privilege escalation or data corruption. The vulnerability specifically targets the xferfax$$ temporary file naming convention used by the fax transfer statistics utility, which creates predictable temporary file names that can be intercepted through symlink attacks.
The technical implementation of this vulnerability involves a classic race condition scenario where the xferfaxstats utility creates temporary files using predictable naming patterns without proper atomic file creation mechanisms. When a local user can influence the creation of symbolic links in the directory where these temporary files are expected to be created, they can establish symlinks that point to arbitrary system files. During the normal execution flow, when the utility attempts to write to the temporary file, it actually writes to the target file specified by the malicious symlink, allowing the attacker to overwrite critical system files, configuration files, or even files owned by privileged users. This represents a direct violation of the principle of least privilege and demonstrates poor file handling practices that align with CWE-367 weakness category related to time-of-check to time-of-use vulnerabilities.
The operational impact of this vulnerability extends beyond simple file overwriting capabilities, as it can enable local users to escalate privileges within the fax system environment. Since HylaFax typically operates with elevated privileges to manage fax services and access system resources, successful exploitation could allow attackers to modify system configuration files, inject malicious code into fax processing pipelines, or corrupt critical system components. The attack vector requires local system access but does not necessitate network connectivity, making it particularly dangerous in environments where local access is not properly restricted. This vulnerability affects systems where the fax service runs with elevated privileges and where the temporary file creation process lacks proper security controls such as secure temporary file creation mechanisms or proper file permission validation.
Mitigation strategies for this vulnerability should focus on implementing secure temporary file creation practices that prevent predictable naming patterns and eliminate race conditions. System administrators should immediately upgrade to HylaFax versions that address this issue, as the vulnerability has been resolved in subsequent releases through proper file handling mechanisms. The solution involves ensuring that temporary files are created atomically with proper permissions and that symbolic link attacks are prevented through directory validation checks. Organizations should also implement proper access controls to limit local system access and monitor for suspicious file system activities in fax-related directories. This vulnerability demonstrates the importance of following secure coding practices and aligns with ATT&CK technique T1059 for executing malicious code through system services, as well as T1068 for privilege escalation through local system vulnerabilities. The fix typically involves modifying the xferfaxstats utility to use secure temporary file creation methods such as creating files with exclusive access flags or using secure temporary directory mechanisms that prevent symbolic link attacks.