CVE-2000-0839 in WinCOM LPD
Summary
by MITRE
WinCOM LPD 1.00.90 allows remote attackers to cause a denial of service via a large number of LPD options to the LPD port (515).
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Analysis
by VulDB Data Team • 05/24/2019
The vulnerability identified as CVE-2000-0839 affects WinCOM LPD version 1.00.90, a line printer daemon implementation that provides print server functionality over the network. This flaw resides in the handling of incoming LPD protocol requests on the standard port 515, which is used for line printer daemon services in Unix and Windows environments. The vulnerability represents a classic denial of service attack vector that exploits the protocol's lack of proper input validation and resource management.
The technical flaw manifests when remote attackers send an excessive number of LPD options to the target system through the LPD port. This results in the service becoming unresponsive or crashing entirely due to resource exhaustion or improper handling of malformed requests. The implementation fails to properly validate the number and size of options provided in LPD requests, allowing attackers to flood the service with malformed data that consumes system resources without proper termination or cleanup mechanisms. This vulnerability falls under CWE-400, which categorizes improper handling of input data leading to resource exhaustion, and specifically relates to CWE-122, which addresses improper restriction of operations within the bounds of a memory buffer.
The operational impact of this vulnerability extends beyond simple service disruption, as it can effectively render the print server unusable for legitimate users while potentially affecting broader network operations that depend on printing services. Organizations relying on WinCOM LPD for print management would experience complete denial of print services until the system is manually restarted or the service is manually terminated. This type of attack aligns with ATT&CK technique T1499.004, which describes network denial of service attacks targeting services and protocols that are critical to business operations. The vulnerability particularly affects environments where print services are critical for business operations and where the system is not properly monitored for unusual traffic patterns on port 515.
Mitigation strategies for this vulnerability include implementing network-level filtering to restrict access to port 515 from trusted sources only, applying the vendor-provided patch or upgrade to a newer version of WinCOM LPD that properly handles malformed requests, and implementing rate limiting or connection throttling mechanisms to prevent resource exhaustion. Organizations should also deploy intrusion detection systems that can identify unusual patterns of LPD traffic and alert administrators to potential attacks. Additionally, regular vulnerability assessments and network monitoring should be conducted to identify systems running vulnerable versions of LPD services, with proper access controls implemented to limit the attack surface. The remediation process should also include establishing baseline network traffic patterns for normal LPD operations to better detect anomalous behavior that could indicate exploitation attempts.