CVE-2006-6411 in WIP 330 Wireless-G IP Phone
Summary
by MITRE
PhoneCtrl.exe in Linksys WIP 330 Wireless-G IP Phone 1.00.06A allows remote attackers to cause a denial of service (crash) via a TCP SYN scan, as demonstrated using TCP ports 1-65535 with nmap.
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Analysis
by VulDB Data Team • 08/01/2019
The vulnerability identified as CVE-2006-6411 affects the PhoneCtrl.exe component of Linksys WIP 330 Wireless-G IP Phone firmware version 1.00.06A, representing a significant security weakness in networked voice communication devices. This flaw manifests as a remote denial of service condition that can be triggered through network-level attacks targeting the device's TCP handling mechanisms. The vulnerability specifically exploits the phone's response to TCP SYN scan attempts, which are common reconnaissance techniques used by attackers to map network topology and identify active services. The attack vector is particularly concerning because it leverages a fundamental networking protocol to disrupt service availability, making it accessible to attackers with minimal specialized tools.
The technical implementation of this vulnerability stems from inadequate input validation and connection handling within the PhoneCtrl.exe process, which fails to properly manage TCP connection requests. When the device receives TCP SYN packets on any port within the range of 1-65535, the system's network stack becomes overwhelmed by the malformed connection attempts, leading to a complete system crash or reboot. This behavior indicates a lack of proper resource management and error handling in the device's TCP/IP stack implementation, where the system does not adequately distinguish between legitimate connection attempts and malicious scan patterns. The vulnerability operates at the network protocol level, bypassing application-level security measures and directly targeting the device's operating system kernel components responsible for connection management.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited by attackers to render the entire IP phone inoperative for extended periods. This denial of service condition affects business communications where reliable voice connectivity is critical, potentially disrupting emergency services, customer support lines, or corporate communication networks. The attack can be executed remotely without requiring physical access or authentication credentials, making it particularly dangerous for devices deployed in unsecured environments. Network administrators may find it difficult to detect such attacks as they appear to be normal network scanning activities, while the actual impact manifests as complete service failure. The vulnerability affects the availability aspect of the CIA triad, specifically targeting the device's ability to maintain continuous operation.
Mitigation strategies for this vulnerability should include implementing network-level protections such as firewall rules that limit incoming TCP SYN connections to only necessary ports, and deploying intrusion detection systems that can identify and block suspicious scanning patterns. Network segmentation should be employed to isolate IP phone devices from critical network infrastructure, reducing the potential impact of successful attacks. Device firmware updates should be implemented immediately upon availability, as this vulnerability was likely addressed in subsequent releases through improved TCP connection handling and resource management. The implementation of rate limiting on TCP connection attempts and connection tracking mechanisms can help prevent the exploitation of this flaw by limiting the number of simultaneous connection requests that the device processes. Organizations should also consider network monitoring solutions that can detect anomalous traffic patterns indicative of port scanning activities and automatically respond by blocking offending IP addresses.
This vulnerability aligns with CWE-122 which describes improper restriction of operations within a limited error handling scope, and relates to ATT&CK technique T1499.004 for network denial of service attacks. The weakness demonstrates poor error handling in network protocol processing and represents a classic example of how insufficient input validation can lead to system instability. The vulnerability also connects to broader security principles regarding secure network programming practices and the importance of implementing robust error handling mechanisms in network services to prevent exploitation through resource exhaustion attacks.