CVE-2005-0017 in mlink
Summary
by MITRE
The f2c translator in the f2c package 3.1 allows local users to read arbitrary files via a symlink attack on temporary files.
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Analysis
by VulDB Data Team • 05/29/2019
The vulnerability identified as CVE-2005-0017 resides within the f2c translator component of the f2c package version 3.1, representing a critical security flaw that enables local attackers to access arbitrary files through a carefully crafted symlink attack against temporary file handling mechanisms. This issue demonstrates a classic race condition vulnerability where the translator creates temporary files without proper security measures, allowing malicious users to manipulate the file system and gain unauthorized access to sensitive data. The f2c package serves as a Fortran to C compiler translator, converting legacy Fortran source code into C code for execution on modern systems, making this vulnerability particularly concerning for environments that rely on automated code translation processes. The flaw specifically manifests when the translator creates temporary files in predictable locations without implementing proper file system permissions or atomic creation mechanisms that would prevent symlink-based attacks.
The technical implementation of this vulnerability exploits the fundamental weakness in temporary file creation procedures within the f2c translator. When processing Fortran source files, the translator generates temporary files to store intermediate compilation results, but these temporary files are created in world-writable directories without proper security controls. Attackers can create symbolic links in the same directory with names that match those expected by the translator, effectively tricking the system into writing sensitive data to locations controlled by the attacker. This type of vulnerability falls under the category of CWE-377 - Insecure Temporary Files, which is classified as a weakness in the design and implementation of temporary file handling mechanisms. The vulnerability represents a privilege escalation vector where local users can bypass normal file access controls and read files they would normally not have permission to access, potentially including system configuration files, user credentials, or proprietary source code.
The operational impact of this vulnerability extends beyond simple unauthorized file access, as it can enable attackers to gather sensitive information that could be used for further exploitation within the system. In environments where the f2c translator is frequently used for compiling scientific or engineering applications, attackers could potentially access source code repositories, configuration files containing database credentials, or other sensitive artifacts that might be processed through the translation pipeline. The attack requires local system access but does not need elevated privileges, making it particularly dangerous in multi-user environments where attackers might have limited access to system resources. The vulnerability also aligns with ATT&CK technique T1059.007 - Command and Scripting Interpreter: Visual Basic, as attackers could potentially use the read access to gather information about system configurations, network settings, or other intelligence that could be leveraged for more sophisticated attacks. The impact is further amplified when considering that many scientific computing environments process sensitive data, making the potential for information disclosure particularly severe.
Mitigation strategies for this vulnerability must address both the immediate implementation flaw and broader system security practices. The primary fix involves modifying the f2c translator to create temporary files using secure methods that prevent symlink attacks, such as using the mkstemp() system call or creating files with restrictive permissions and in secure temporary directories. System administrators should also implement proper file system permissions, ensuring that temporary directories are not world-writable and that the translator runs with minimal required privileges. The vulnerability highlights the importance of following secure coding practices as outlined in industry standards and security frameworks, particularly those addressing temporary file handling and privilege management. Organizations should also consider implementing monitoring and logging mechanisms to detect unusual file access patterns that might indicate exploitation attempts. Regular security audits and code reviews should specifically examine temporary file handling procedures, as this vulnerability demonstrates how seemingly minor implementation details can lead to significant security consequences. Additionally, the use of privilege separation and sandboxing techniques can further reduce the impact of such vulnerabilities by limiting the potential damage even if exploitation occurs.