CVE-2008-5371 in screenie
Summary
by MITRE
screenie in screenie 1.30.0 allows local users to overwrite arbitrary files via a symlink attack on a /tmp/.screenie.##### temporary file.
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Analysis
by VulDB Data Team • 08/03/2021
The vulnerability identified as CVE-2008-5371 affects the screenie application version 1.30.0 and represents a classic temporary file creation race condition that enables local privilege escalation through symbolic link manipulation. This flaw exists within the application's handling of temporary files in the /tmp directory, specifically targeting the file path /tmp/.screenie which is used during the application's operation. The vulnerability stems from inadequate security checks during temporary file creation, allowing malicious users to exploit the predictable naming convention and timing window to create symbolic links that redirect the application's file operations to arbitrary locations on the filesystem.
The technical implementation of this vulnerability aligns with CWE-377, which catalogs weaknesses related to insecure temporary file handling, and more specifically with CWE-378, which addresses the creation of temporary files with insecure permissions. The attack vector exploits the fundamental flaw in how screenie manages its temporary file lifecycle, where the application creates temporary files without proper security measures to prevent symlink attacks. When screenie executes and attempts to write to /tmp/.screenie, an attacker who has already created a symbolic link at that location can cause the application to write data to a file chosen by the attacker rather than the intended temporary file. This represents a privilege escalation vulnerability since the application typically runs with elevated privileges, and the attacker can leverage this to overwrite files with potentially malicious content.
The operational impact of this vulnerability extends beyond simple file overwriting, as it can enable attackers to modify critical system files, configuration data, or even executable programs that may be owned by the application's running user. The vulnerability is particularly dangerous in multi-user environments where local users can exploit this weakness to gain unauthorized access to system resources or manipulate application behavior. Attackers can leverage this weakness to plant malicious code, modify application settings, or potentially create backdoors for persistent access. The attack requires local system access and the ability to create symbolic links, making it a local privilege escalation vulnerability rather than a remote attack vector, but the implications remain significant for system integrity and security.
Mitigation strategies for this vulnerability must address the core issue of insecure temporary file handling within the application. The most effective approach involves implementing proper temporary file creation mechanisms that utilize secure file creation patterns, such as creating files with restrictive permissions and using atomic operations that prevent symlink attacks. The application should employ techniques such as creating temporary files with unique, unpredictable names and ensuring that the file creation process includes proper validation to detect and reject symbolic links. Additionally, system administrators should implement proper file permissions and access controls to limit the impact of such vulnerabilities. According to ATT&CK framework, this vulnerability maps to T1068, which covers local privilege escalation through the exploitation of insecure file permissions, and T1548.001, which covers abuse of system privileges through local privilege escalation techniques. The vulnerability also aligns with the principle of least privilege and proper secure coding practices as outlined in the OWASP Secure Coding Practices, emphasizing the need for applications to never trust user-provided data and to always validate temporary file operations against potential symlink attacks.