CVE-2008-4950 in dpkg-cross
Summary
by MITRE
** DISPUTED ** gccross in dpkg-cross 2.3.0 allows local users to overwrite arbitrary files via a symlink attack on the tmp/gccross2.log temporary file. NOTE: the vendor disputes this vulnerability, stating that "There is no sense in this bug - the script ... is called under specific cross-building environments within a chroot."
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Analysis
by VulDB Data Team • 08/07/2024
The vulnerability described in CVE-2008-4950 pertains to a potential file overwrite issue within the dpkg-cross package version 2.3.0, specifically involving the gccross script. This flaw manifests as a symlink attack vulnerability that could potentially allow local users to overwrite arbitrary files on the system. The issue arises from the insecure handling of temporary files during cross-compilation processes, where the gccross script creates a temporary file named tmp/gccross2.log without proper safeguards against symbolic link manipulation.
The technical exploitation of this vulnerability relies on the principle of time-of-check to time-of-use race conditions commonly referenced in CWE-367. When the gccross script executes within a cross-building environment, it creates a temporary file that can be manipulated by an attacker who has write access to the directory containing the temporary file. The attacker can create a symbolic link with the same name as the temporary file, causing the script to write to an unintended location. This type of vulnerability falls under the broader category of insecure temporary file handling as defined in CWE-377, where the creation and use of temporary files lacks proper security measures to prevent symlink attacks.
The operational impact of this vulnerability extends beyond simple file overwrites, as it represents a privilege escalation vector that could potentially allow attackers to modify critical system files or inject malicious content into the cross-compilation process. While the vendor has disputed the validity of this vulnerability by stating that the script is executed within specific chroot environments, this assertion raises questions about the actual security posture of the cross-compilation infrastructure. The vendor's position suggests that the vulnerability only exists in specific contexts, but the fundamental flaw in temporary file handling remains regardless of the execution environment, particularly when considering that chroot environments may not always provide complete isolation.
The security implications of this vulnerability align with ATT&CK technique T1059.007 for execution through scripting and T1548.001 for privilege escalation through setuid binaries. The cross-compilation environment typically requires elevated privileges to function properly, making this vulnerability particularly concerning as it could enable attackers to manipulate the build process and potentially introduce malicious code into the compiled software. The fact that this vulnerability is disputed by the vendor does not diminish the potential risk, as the underlying issue of insecure temporary file handling represents a fundamental security flaw that should be addressed regardless of the specific execution context.
Mitigation strategies for this vulnerability should focus on implementing secure temporary file creation practices, including the use of umask settings, proper file permissions, and atomic file creation methods that prevent symlink attacks. The dpkg-cross package should be updated to use secure temporary file handling techniques that ensure the temporary file is created with exclusive access permissions and proper ownership. Additionally, system administrators should consider implementing monitoring for unauthorized file modifications in temporary directories and ensure that cross-compilation environments are properly isolated and secured. The vulnerability demonstrates the importance of secure coding practices in build tools and the need for thorough security reviews of scripts that handle temporary files in privileged contexts.