CVE-2018-14336 in WR840N
Summary
by MITRE
TP-Link WR840N devices allow remote attackers to cause a denial of service (connectivity loss) via a series of packets with random MAC addresses.
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Analysis
by VulDB Data Team • 07/28/2024
The TP-Link WR840N wireless router model presents a significant denial of service vulnerability that affects network connectivity for remote attackers. This vulnerability stems from the device's insufficient validation of incoming network packets, specifically targeting the MAC address handling mechanism within the wireless access point functionality. The flaw manifests when attackers send a sequence of packets containing randomly generated MAC addresses, which the device fails to properly process or filter. This weakness resides in the router's wireless protocol stack implementation, where the authentication and connection management processes do not adequately sanitize or validate the source MAC addresses of incoming frames.
The technical exploitation of this vulnerability operates through a straightforward yet effective mechanism that leverages the device's weak packet filtering capabilities. When the WR840N receives packets with random MAC addresses, the router's wireless subsystem becomes overwhelmed with malformed connection attempts that it cannot properly handle or discard. This condition causes the device to enter a state where legitimate wireless connections become disrupted or entirely impossible to establish. The vulnerability's impact extends beyond simple service interruption as it affects the core wireless functionality that users rely upon for network access. The device essentially becomes unable to maintain stable wireless connections while simultaneously rejecting legitimate client attempts to connect to the network.
From an operational perspective, this vulnerability creates substantial security implications for any organization or individual utilizing TP-Link WR840N devices in their network infrastructure. The denial of service condition can persist for extended periods, requiring manual intervention to restore normal connectivity, which may involve device rebooting or configuration resets. Network administrators face the challenge of identifying the root cause of connectivity issues, as the symptoms appear as intermittent wireless failures rather than obvious system crashes. This vulnerability particularly affects environments where wireless access is critical, such as small office networks, home offices, or public access points where continuous connectivity is essential for business operations. The attack vector is remarkably simple to execute, requiring only basic network packet generation tools and making it accessible to attackers with minimal technical expertise.
The vulnerability aligns with CWE-225, which addresses weaknesses in input validation and improper handling of malformed data, and it maps to ATT&CK technique T1499.004 for network denial of service attacks. The device's failure to properly validate MAC addresses represents a classic case of insufficient input sanitization where the wireless subsystem does not implement adequate bounds checking or packet filtering mechanisms. This weakness creates an exploitable condition where an attacker can consume system resources or trigger state machine failures within the wireless access point component. The lack of proper rate limiting or connection attempt throttling mechanisms exacerbates the impact, allowing a single attacker to maintain sustained disruption of the wireless service. Security professionals should note that this vulnerability demonstrates the importance of robust packet validation in network infrastructure devices, particularly those handling wireless communications where resource exhaustion attacks can have immediate and significant operational impacts.
Organizations should implement immediate mitigations including firmware updates from TP-Link, which address the specific packet validation issues in the wireless subsystem. Network segmentation strategies can help isolate vulnerable devices from critical systems, while monitoring solutions should be deployed to detect unusual patterns of MAC address activity that may indicate exploitation attempts. The implementation of proper rate limiting on wireless connection attempts and enhanced logging of wireless authentication events provides additional layers of defense. Device administrators should consider disabling unused wireless features and implementing MAC address filtering as temporary compensating controls. Long-term solutions require regular firmware updates and comprehensive security assessments of network infrastructure devices to identify similar validation weaknesses. The vulnerability also underscores the necessity of applying security patches promptly and maintaining awareness of vendor advisories for network equipment.