CVE-2005-2918 in gtkdiskfree
Summary
by MITRE
The open_cmd_tube function in mount.c for gtkdiskfree 1.9.3 and earlier allows local users to overwrite arbitrary files via a symlink attack on the gtkdiskfree temporary file.
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Analysis
by VulDB Data Team • 06/10/2019
The vulnerability described in CVE-2005-2918 represents a classic race condition and privilege escalation issue affecting the gtkdiskfree utility version 1.9.3 and earlier. This flaw exists within the open_cmd_tube function in the mount.c source file, where the application creates temporary files without proper security measures that could be exploited by local attackers. The vulnerability specifically targets the way the utility handles temporary file creation during disk space monitoring operations, creating an opportunity for malicious users to manipulate the system's file permissions and overwrite critical files.
The technical implementation of this vulnerability stems from the improper handling of temporary file creation in a multi-user environment where the gtkdiskfree utility executes with elevated privileges. When the open_cmd_tube function generates temporary files, it does not employ secure methods such as creating files with exclusive access permissions or using secure temporary file creation functions. Attackers can exploit this by creating symbolic links in the expected temporary file locations before the utility attempts to create them, thereby redirecting the utility's file operations to overwrite arbitrary files on the system. This type of attack falls under the category of insecure temporary file handling as classified by CWE-377, specifically CWE-378 which addresses the creation of temporary files with insecure permissions.
The operational impact of this vulnerability is significant for systems running affected versions of gtkdiskfree, as local attackers with minimal privileges can leverage this flaw to overwrite critical system files, configuration files, or even binaries that the utility might access during its operation. The attack vector requires the attacker to have local access to the system but does not require network connectivity or complex exploitation techniques. The vulnerability essentially allows for privilege escalation from a regular user account to a higher privilege level, potentially enabling attackers to modify system files, install malicious code, or gain persistent access to the compromised system. This aligns with ATT&CK technique T1068 which covers the use of privilege escalation techniques through insecure file handling.
Mitigation strategies for CVE-2005-2918 should focus on immediate patching of the gtkdiskfree utility to versions that properly implement secure temporary file handling mechanisms. System administrators should ensure that all instances of gtkdiskfree are updated to versions that address this vulnerability, typically through the distribution's package management system. Additionally, implementing proper file permission controls and monitoring for unauthorized file modifications can help detect potential exploitation attempts. The recommended approach includes using secure temporary file creation functions such as mkstemp() instead of relying on predictable temporary file names, implementing proper file ownership checks, and ensuring that temporary files are created with restrictive permissions that prevent unauthorized access. Organizations should also conduct regular security audits to identify other applications that might be susceptible to similar temporary file handling vulnerabilities, as this represents a common class of security flaws that can lead to privilege escalation attacks.