CVE-2005-0334 in Psus4 Printserver
Summary
by MITRE
Linksys PSUS4 running firmware 6032 allows remote attackers to cause a denial of service (device crash) via an HTTP POST request containing an unknown parameter without a value.
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Analysis
by VulDB Data Team • 07/22/2017
The vulnerability identified as CVE-2005-0334 affects Linksys PSUS4 wireless access points running firmware version 6032, representing a critical denial of service weakness that can be exploited remotely by malicious actors. This issue stems from the device's insufficient input validation mechanisms within its web interface handling code, specifically when processing HTTP POST requests. The flaw manifests when an attacker crafts a malicious HTTP POST request containing an unknown parameter that lacks a value, causing the device to crash and become unavailable to legitimate users.
The technical implementation of this vulnerability resides in the web server component of the Linksys PSUS4 firmware, which fails to properly sanitize or validate incoming HTTP POST parameters. When the device receives a malformed POST request with an unrecognized parameter, the parsing routine does not adequately handle the edge case, leading to a buffer overflow condition or memory corruption that ultimately results in the device crashing. This behavior aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-122, which covers stack-based buffer overflow issues. The vulnerability demonstrates poor input validation practices where the system does not properly check parameter boundaries or handle unexpected input formats.
From an operational perspective, this vulnerability presents significant security implications for network infrastructure deployments that rely on Linksys PSUS4 devices. The remote exploit capability means that attackers can potentially disrupt network services without requiring physical access or local network credentials, making it particularly dangerous in enterprise environments where wireless access points serve as critical network components. The device crash resulting from this attack effectively creates a denial of service condition that can impact legitimate users attempting to access network resources through the affected wireless infrastructure. Network administrators may experience service interruptions that could affect business operations, especially in environments where wireless connectivity is essential for productivity and communication.
The attack vector for this vulnerability is straightforward and requires minimal technical expertise to execute, making it particularly concerning for widespread exploitation. An attacker simply needs to send a specially crafted HTTP POST request to the device's web interface, which can be accomplished through various means including automated scanning tools or manual exploitation techniques. The lack of authentication requirements for this specific attack vector means that even unauthenticated users can potentially disrupt services. This vulnerability also aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and demonstrates how improper input validation can create exploitable conditions that lead to service disruption. Organizations using affected Linksys PSUS4 devices should implement immediate mitigations including firmware updates, network segmentation, and monitoring for suspicious HTTP traffic patterns.
Mitigation strategies for this vulnerability should prioritize firmware updates from Linksys to address the underlying parsing flaw in the web server component. Network administrators should also implement access controls to restrict HTTP access to the device's web interface, potentially through firewall rules or network access control lists that limit which systems can reach the device's management interface. Additionally, deploying network monitoring tools to detect anomalous HTTP POST requests containing unusual parameters can help identify exploitation attempts. The vulnerability serves as a reminder of the importance of input validation in embedded systems and web applications, particularly in network infrastructure devices where service availability is critical. Organizations should also consider implementing network intrusion detection systems that can identify and alert on suspicious HTTP traffic patterns that may indicate exploitation attempts against similar vulnerabilities in other network equipment.