CVE-2000-0879 in LPPlus
Summary
by MITRE
LPPlus programs dccsched, dcclpdser, dccbkst, dccshut, dcclpdshut, and dccbkstshut are installed setuid root and world executable, which allows arbitrary local users to start and stop various LPD services.
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Analysis
by VulDB Data Team • 05/27/2018
The vulnerability described in CVE-2000-0879 represents a critical privilege escalation issue within the LPPlus printing system implementation on Unix-based systems. This vulnerability affects multiple daemon programs including dccsched, dcclpdser, dccbkst, dccshut, dcclpdshut, and dccbkstshut, which are all installed with setuid root permissions and world executable access. The fundamental flaw lies in the improper privilege management where these system services are designed to operate with elevated root privileges while simultaneously allowing unrestricted execution by any local user. This configuration creates a direct path for privilege escalation attacks as malicious users can invoke these programs to perform administrative functions without proper authentication or authorization.
The technical implementation of this vulnerability stems from the violation of the principle of least privilege, where programs should only operate with the minimum permissions necessary to perform their intended functions. These LPPlus services were designed to control Line Printer Daemon (LPD) operations, which typically require root privileges for system-level operations such as starting, stopping, or managing print services. However, the combination of setuid root permissions with world executable permissions creates a dangerous exposure where any local user can execute these programs with root privileges. This design flaw allows for arbitrary code execution at the system level, as demonstrated by the ability to start and stop various LPD services through these vulnerable programs. The vulnerability directly maps to CWE-276, which addresses improper file permissions and inadequate access control mechanisms, and aligns with ATT&CK technique T1068, which covers privilege escalation through local exploits.
The operational impact of this vulnerability extends far beyond simple privilege escalation, creating significant security implications for affected systems. Local users who exploit this vulnerability can effectively gain root access to the system, enabling them to modify critical system files, install malicious software, or establish persistent backdoors. The ability to start and stop LPD services provides attackers with additional attack vectors, as they can disrupt printing services, potentially causing denial of service conditions, or manipulate print queues to capture sensitive data. Furthermore, since these programs are part of the core printing infrastructure, their compromise can lead to information disclosure, system integrity violations, and potential lateral movement within networked environments where printing services are shared across multiple systems. The vulnerability affects Unix and Unix-like systems where LPPlus is installed, particularly impacting enterprise environments that rely on centralized printing services and may have multiple users with local access to affected systems.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term architectural improvements to prevent similar privilege escalation issues. The most immediate and effective solution involves changing the file permissions of the vulnerable programs to remove the setuid bit and restrict execution permissions to authorized users only. System administrators should also implement proper access controls through discretionary access control lists or role-based access controls to ensure that only legitimate system administrators can execute these programs. Additionally, the affected system should be audited for other setuid programs that may exhibit similar vulnerabilities, as this represents a broader pattern of insecure privilege management. Regular security audits should be conducted to identify and remediate similar issues in other system components, particularly focusing on the principle of least privilege implementation. The vulnerability serves as a clear example of why system administrators should regularly review and audit setuid programs, as these represent some of the most dangerous security exposures in Unix-based systems and require careful monitoring and control to prevent unauthorized privilege escalation attacks.