CVE-2008-5146 in ctn
Summary
by MITRE
add-accession-numbers in ctn 3.0.6 allows local users to overwrite arbitrary files via a symlink attack on the /tmp/accession temporary file.
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Analysis
by VulDB Data Team • 10/14/2018
The vulnerability identified as CVE-2008-5146 resides within the ctn software version 3.0.6 and specifically affects the add-accession-numbers component. This flaw represents a classic symlink attack vector that enables local users to manipulate temporary file creation processes and subsequently overwrite arbitrary files on the system. The issue stems from improper handling of temporary files during the accession number addition process, creating a window of opportunity for privilege escalation and data integrity compromise.
The technical implementation of this vulnerability follows a well-established pattern of insecure temporary file handling that aligns with CWE-377, which addresses insecure temporary file creation. The ctn software creates temporary files in the /tmp/accession location without adequate security measures to prevent symbolic link attacks. When a local user can predict or influence the creation of temporary files, they can establish a symbolic link pointing to a target file of their choice before the legitimate program creates the temporary file. This race condition allows attackers to redirect file operations to arbitrary locations, effectively enabling them to overwrite system files, configuration files, or even files belonging to other users with elevated privileges.
From an operational perspective, this vulnerability presents significant risks to system security and integrity. Local users who can execute the add-accession-numbers utility can leverage this flaw to overwrite critical system files, potentially leading to privilege escalation, denial of service, or data corruption. The attack requires local system access but does not necessitate network connectivity, making it particularly concerning for multi-user systems where privilege separation is crucial. The impact extends beyond simple file overwrites, as attackers could target configuration files, log files, or even binaries that are processed by the system, potentially enabling further exploitation or persistent access.
The attack vector demonstrates characteristics consistent with techniques documented in the MITRE ATT&CK framework under the T1059.007 sub-technique for command and scripting interpreter, specifically focusing on local privilege escalation through file system manipulation. The vulnerability's exploitation process involves creating a symbolic link in the /tmp directory before the legitimate program creates its temporary file, which represents a common pattern in Unix-like systems where /tmp is world-writable and lacks proper security controls. This type of vulnerability underscores the importance of proper temporary file handling practices, including the use of secure temporary file creation functions that prevent symbolic link attacks and ensure atomic file creation processes.
Mitigation strategies for CVE-2008-5146 should focus on implementing secure temporary file handling mechanisms that prevent the race conditions exploited by this vulnerability. System administrators should immediately patch the ctn software to version 3.0.7 or later where this vulnerability has been addressed through proper temporary file creation methods. Organizations should also implement monitoring for suspicious temporary file creation patterns and consider implementing stricter permissions on temporary directories. Additionally, the principle of least privilege should be enforced, ensuring that the add-accession-numbers utility runs with minimal required permissions and that temporary file creation uses secure methods such as open() with O_EXCL flag to prevent symlink attacks. The vulnerability serves as a reminder of the critical importance of secure coding practices and proper file system security controls in preventing local privilege escalation attacks.