CVE-2008-3791 in Lightweight X11 Desktop Environment
Summary
by MITRE
src/main-win.c in GPicView 0.1.9 in Lightweight X11 Desktop Environment (LXDE) allows local users to overwrite arbitrary files via a symlink attack on the /tmp/rot.jpg temporary file.
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Analysis
by VulDB Data Team • 11/30/2017
The vulnerability described in CVE-2008-3791 represents a classic symlink attack scenario that exploits insecure temporary file handling within the GPicView image viewer component of the Lightweight X11 Desktop Environment. This flaw exists in the src/main-win.c source file of GPicView version 0.1.9, where the application creates temporary files without proper security checks, making it susceptible to privilege escalation and arbitrary file overwrite attacks. The vulnerability specifically targets the /tmp/rot.jpg temporary file location, which serves as a critical point of attack for local users seeking to manipulate system files.
The technical implementation of this vulnerability stems from the application's failure to validate or securely create temporary files in the /tmp directory. When GPicView processes images, it generates a temporary file named rot.jpg in the system's temporary directory without implementing proper atomic file creation mechanisms. This insecure practice allows local attackers to create symbolic links with the same name in the target directory, causing the application to write data to the attacker-controlled symlink destination instead of the intended temporary file location. The flaw directly maps to CWE-353, which addresses the weakness of using insecure temporary files, and also aligns with CWE-22, covering improper limitation of a pathname to a restricted directory.
The operational impact of this vulnerability extends beyond simple file overwrites, as it provides local attackers with the capability to modify critical system files or inject malicious content into arbitrary locations within the filesystem. An attacker could potentially leverage this vulnerability to replace system binaries, modify configuration files, or create backdoor access points within the LXDE environment. The attack requires local system access but does not require elevated privileges, making it particularly dangerous in multi-user environments where users might have legitimate access to the desktop environment. This vulnerability also demonstrates how seemingly innocuous image processing applications can become attack vectors when proper security measures are not implemented.
Mitigation strategies for this vulnerability involve implementing secure temporary file creation practices such as using the mkstemp() system call or similar atomic file creation functions that guarantee unique file names and prevent symlink attacks. The application should also validate that temporary files are created in secure directories with appropriate permissions and should avoid creating files in world-writable directories like /tmp. Additionally, the LXDE project should implement proper input validation and sanitization of file paths to prevent path traversal attacks. This vulnerability highlights the importance of adhering to security best practices such as those outlined in the Open Web Application Security Project (OWASP) guidelines for secure file handling and the ATT&CK framework's emphasis on privilege escalation techniques through insecure file operations. Organizations should also ensure that all desktop applications undergo proper security review processes to identify and remediate similar vulnerabilities before deployment in production environments.