CVE-2007-0007 in gnucash
Summary
by MITRE
gnucash 2.0.4 and earlier allows local users to overwrite arbitrary files via a symlink attack on the (1) gnucash.trace, (2) qof.trace, and (3) qof.trace.[PID] temporary files.
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Analysis
by VulDB Data Team • 07/15/2019
The vulnerability described in CVE-2007-0007 represents a classic symlink attack scenario that affects the gnucash financial application version 2.0.4 and earlier. This flaw resides in the application's handling of temporary files during its execution lifecycle, creating a significant security risk for local users who can exploit the weakness to overwrite arbitrary files on the system. The vulnerability specifically targets three temporary files: gnucash.trace, qof.trace, and qof.trace.[PID], where the PID suffix indicates process identifier variations. The attack vector leverages the predictable naming pattern of these temporary files combined with the application's failure to properly validate or secure temporary file creation processes.
The technical implementation of this vulnerability stems from improper temporary file handling practices within the gnucash application codebase. When the application creates temporary files for logging or debugging purposes, it does not employ secure temporary file creation methods that would prevent symbolic link attacks. This behavior aligns with CWE-377, which addresses insecure temporary file creation practices, and specifically relates to CWE-378, which covers the creation of temporary files with insecure permissions. The flaw operates under the assumption that the temporary files are created in predictable locations without proper access control measures or atomic file creation mechanisms that would prevent attackers from pre-creating symbolic links that the application would subsequently overwrite.
From an operational perspective, this vulnerability poses a serious threat to system integrity and data confidentiality for local users who have access to the affected gnucash application. An attacker with local access can create symbolic links in the temporary file directories that point to critical system files or user data, then trigger the gnucash application to create temporary files with the same names. This results in the attacker's symbolic links being overwritten with content from the application's temporary file creation process, potentially allowing for privilege escalation or data manipulation attacks. The impact extends beyond simple file overwrites to include potential privilege escalation scenarios where attackers could target system files with elevated permissions.
The attack scenario typically involves an attacker creating symbolic links in the temporary file directories before executing the gnucash application, where the application will subsequently overwrite these links with actual temporary files. This attack model is consistent with techniques documented in the MITRE ATT&CK framework under the T1059.001 technique for executing commands through command-line interfaces, and more specifically relates to privilege escalation techniques. The vulnerability also connects to broader concepts in the software security domain related to time-of-check to time-of-use race conditions, which are classified under CWE-367, where the state of a resource changes between the time it is checked and when it is used.
Mitigation strategies for this vulnerability require immediate application updates to versions that properly implement secure temporary file creation practices. System administrators should ensure that all gnucash installations are updated to versions that address this specific flaw through proper temporary file handling mechanisms such as using umask values, creating temporary files with unique names, or implementing atomic file creation processes. Additional defensive measures include restricting write permissions on temporary file directories, implementing proper file system access controls, and monitoring for suspicious symbolic link creation patterns. The vulnerability also highlights the importance of secure coding practices and adherence to security standards such as those outlined in the Open Web Application Security Project (OWASP) Top 10, particularly those related to secure temporary file handling and input validation. Organizations should also consider implementing application whitelisting controls to prevent unauthorized execution of vulnerable versions of gnucash and conduct regular security assessments to identify similar insecure temporary file handling patterns in other applications.