CVE-2002-1366 in CUPS
Summary
by MITRE
Common Unix Printing System (CUPS) 1.1.14 through 1.1.17 allows local users with lp privileges to create or overwrite arbitrary files via file race conditions, as demonstrated by ice-cream.
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Analysis
by VulDB Data Team • 05/12/2019
The Common Unix Printing System CUPS vulnerability identified as CVE-2002-1366 represents a critical file race condition flaw that affects versions 1.1.14 through 1.1.17. This vulnerability specifically targets local users who possess lp privileges, which are typically granted to users who need to submit print jobs to the system. The flaw enables these privileged users to manipulate the file system in ways that could lead to arbitrary file creation or overwriting, posing significant security risks to Unix-based systems that rely on CUPS for printing operations. The vulnerability was demonstrated through the ice-cream attack vector, which showcases how malicious users can exploit the timing window in file operations to gain unauthorized system access.
The technical implementation of this vulnerability stems from improper file handling procedures within the CUPS printing subsystem. When print jobs are processed, the system creates temporary files during the print queue management process. The race condition occurs because the system checks for file existence and creates files in separate operations that are not atomic. This timing gap allows a malicious user with lp privileges to create a symbolic link or manipulate file paths between the existence check and the actual file creation. The vulnerability is classified under CWE-367, which specifically addresses Time-of-Check to Time-of-Use (TOCTOU) race conditions, making it a classic example of improper resource management where the system state changes between the time a check is performed and when the resource is accessed.
The operational impact of this vulnerability extends beyond simple file manipulation, as it can potentially lead to privilege escalation and system compromise. Local users with lp privileges can leverage this weakness to overwrite critical system files, inject malicious code into print job processing, or create files with elevated permissions that could be executed by the printing system. The ice-cream demonstration reveals that attackers can exploit this flaw to gain persistent access to the system, as the compromised print system could be used to maintain control over the affected Unix environment. This vulnerability directly relates to ATT&CK technique T1059, which covers command and script injection, and T1068, which addresses local privilege escalation, making it a multi-faceted threat that can be weaponized in various attack scenarios.
Mitigation strategies for CVE-2002-1366 should focus on immediate system updates to versions that address the race condition vulnerability. Organizations should implement strict access controls for lp privileges, ensuring that only trusted users have these permissions. The system administrators should also consider implementing proper file system permissions and monitoring for unusual file creation patterns in the print spool directories. Additionally, the vulnerability highlights the importance of atomic operations in system design and proper resource management practices. Security hardening measures should include disabling unnecessary print services, implementing proper logging of print job activities, and conducting regular security audits of printing subsystems. The fix for this vulnerability requires changes to how CUPS handles temporary file creation, ensuring that file operations are atomic and that proper locking mechanisms are implemented to prevent race conditions during file system interactions.