CVE-2004-1268 in CUPS
Summary
by MITRE
lppasswd in cups 1.1.22 ignores write errors when modifying the cups passwd file which allows local users to corrupt the file by filling the associated file system and triggering the write errors.
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Analysis
by VulDB Data Team • 05/29/2019
The vulnerability described in CVE-2004-1268 resides within the Line Printer Daemon (LPD) password management functionality of the Common Unix Printing System (CUPS) version 1.1.22. This issue specifically affects the lppasswd utility which is responsible for managing user authentication credentials for printer access. The flaw represents a critical security oversight in how the system handles file I/O operations during password modifications, creating a pathway for local attackers to intentionally corrupt system files through deliberate resource exhaustion.
The technical implementation of this vulnerability stems from improper error handling within the lppasswd utility's file modification process. When the utility attempts to write changes to the CUPS password file, it fails to properly check for write errors that occur during the file I/O operation. This behavior aligns with CWE-704, which categorizes improper error handling as a weakness that can lead to data corruption and system instability. The utility continues execution regardless of whether the write operation succeeds or fails, allowing the system to proceed with an incomplete or corrupted password file.
The operational impact of this vulnerability is significant for local attackers who possess the ability to manipulate filesystem resources. By filling the associated filesystem to capacity, an attacker can trigger write errors that the lppasswd utility ignores, thereby corrupting the password file. This corruption can lead to multiple security consequences including unauthorized access to printer resources, denial of service conditions for legitimate users, and potential privilege escalation opportunities. The vulnerability specifically affects systems where local users have the capability to consume filesystem space, which is typically a common scenario in multi-user environments.
The attack vector for this vulnerability requires local system access and the ability to control filesystem space allocation, making it particularly concerning in shared computing environments where multiple users have access to the same system resources. The flaw demonstrates a fundamental failure in input validation and error recovery mechanisms, as outlined in the ATT&CK framework under technique T1078 for Valid Accounts and T1499 for Endpoint Denial of Service. This vulnerability essentially allows attackers to exploit a system's resource management to create persistent security issues that can compromise the integrity of the printer access control system.
Mitigation strategies for this vulnerability should focus on implementing proper error handling within the lppasswd utility, ensuring that all write operations are validated before proceeding with subsequent operations. System administrators should consider implementing filesystem monitoring to detect unusual space consumption patterns that might indicate exploitation attempts. The recommended approach includes updating to a patched version of CUPS where proper error handling has been implemented, as well as implementing access controls that limit local user capabilities to prevent resource exhaustion attacks. Additionally, regular monitoring of system logs for unusual file I/O patterns can help detect potential exploitation attempts before they result in successful corruption of critical system files.