CVE-2000-0615 in LPRng
Summary
by MITRE
LPRng 3.6.x improperly installs lpd as setuid root, which can allow local users to append lpd trace and logging messages to files.
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Analysis
by VulDB Data Team • 05/27/2018
The vulnerability identified as CVE-2000-0615 affects LPRng version 3.6.x and represents a significant security flaw in the print spooler daemon implementation. This issue stems from the improper installation of the lpd daemon with setuid root permissions, creating a critical privilege escalation vector that local attackers can exploit to gain elevated system access. The vulnerability specifically targets the logging and tracing mechanisms within the print service, allowing malicious users to manipulate system files through crafted trace messages.
The technical flaw manifests in the improper privilege management of the lpd daemon process, which should not be running with root privileges during normal operation. When lpd is installed with setuid root, it inherits the highest system privileges, enabling it to perform operations that should be restricted to authorized administrators only. This design flaw allows local users to append trace and logging messages to arbitrary files on the system, potentially leading to unauthorized file modifications, log poisoning, or even complete system compromise depending on the target files and their permissions.
The operational impact of this vulnerability extends beyond simple file manipulation as it provides a persistent backdoor mechanism for attackers to maintain access and escalate privileges over time. Local users who can execute the lpd service can leverage this flaw to create malicious log entries that may be processed by system monitoring tools, potentially leading to further exploitation through log analysis vulnerabilities or by corrupting system integrity checks. The vulnerability also affects system auditing capabilities since attackers can manipulate the logging infrastructure to hide their activities or create false positive alerts that obscure legitimate security incidents.
From a cybersecurity perspective, this vulnerability aligns with CWE-276, which addresses improper privilege management in software systems, and represents a classic example of privilege escalation through setuid binary exploitation. The attack vector follows patterns commonly associated with the ATT&CK technique T1068, which involves the exploitation of legitimate credentials and system access to gain elevated privileges. Organizations using LPRng 3.6.x should immediately implement mitigations including removing setuid permissions from the lpd binary, implementing proper access controls for logging directories, and conducting comprehensive system audits to detect any potential exploitation attempts. The recommended remediation includes upgrading to a patched version of LPRng or applying the appropriate security patches that address the improper privilege escalation mechanism and restrict the daemon's file system access permissions to prevent unauthorized file modifications through logging channels.