CVE-2002-0129 in efax
Summary
by MITRE
efax 0.9 and earlier, when installed setuid root, allows local users to read arbitrary files via the -d option, which prints the contents of the file in a warning message.
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Analysis
by VulDB Data Team • 06/06/2018
The vulnerability identified as CVE-2002-0129 represents a critical privilege escalation and information disclosure flaw in efax version 0.9 and earlier installations. This issue manifests when the efax application is configured with the setuid root bit set, creating a dangerous condition where local users can exploit the software's handling of the -d option to gain unauthorized access to sensitive system files. The vulnerability operates through a fundamental design flaw in how the application processes command-line arguments, specifically when the -d flag is utilized, which triggers the display of file contents within warning messages.
The technical implementation of this vulnerability stems from inadequate input validation and improper privilege handling within the efax binary. When a local user invokes the efax utility with the -d option followed by a path to any file on the system, the application fails to properly sanitize the input before processing it. This lack of input sanitization allows attackers to manipulate the program flow and cause it to read and display the contents of arbitrary files, including system configuration files, password databases, or other sensitive data that should remain protected. The vulnerability is particularly concerning because efax is designed to operate with elevated privileges due to its setuid root configuration, yet it fails to properly validate or restrict file access during its operation.
The operational impact of CVE-2002-0129 extends beyond simple information disclosure to encompass potential privilege escalation capabilities that could enable attackers to gain root access to affected systems. Local users who can execute efax with setuid root permissions can leverage this vulnerability to read files that would normally be restricted to root access only, potentially exposing passwords, private keys, system configuration details, or other sensitive information. This vulnerability directly violates the principle of least privilege and represents a classic case of insecure file handling in setuid applications. The flaw aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, and CWE-264, which addresses permissions, privileges, and access controls.
From an attack perspective, this vulnerability demonstrates the dangers of improper privilege management in legacy software systems and highlights the importance of secure coding practices in setuid applications. The ATT&CK framework categorizes this as a privilege escalation technique through exploitation of insecure file handling, specifically falling under the category of "Exploitation for Privilege Escalation" where local users can leverage existing system vulnerabilities to elevate their privileges. The vulnerability also represents a failure in input validation and privilege separation, making it particularly dangerous in environments where efax is commonly used for fax operations but remains configured with elevated permissions. Organizations should note that this vulnerability was present in software versions that were considered stable and widely deployed, emphasizing the need for continuous security assessment of even mature applications.
Mitigation strategies for CVE-2002-0129 must address both the immediate security risk and the underlying architectural issues that enabled the vulnerability. The most effective remediation involves removing the setuid bit from efax installations or upgrading to a patched version that properly validates input and restricts file access. System administrators should implement proper access controls and file permissions to prevent unauthorized users from executing the vulnerable application. Additionally, organizations should conduct comprehensive audits of setuid applications and ensure that all such binaries undergo rigorous security testing. The vulnerability underscores the importance of following secure coding practices and implementing proper input validation mechanisms in all applications that operate with elevated privileges. Regular security assessments and vulnerability scanning should include checks for setuid applications that may present similar risks, particularly in legacy systems where security updates may not be regularly applied.