CVE-2018-17009 in TL-WR886N
Summary
by MITRE
An issue was discovered on TP-Link TL-WR886N 6.0 2.3.4 and TL-WR886N 7.0 1.1.0 devices. Authenticated attackers can crash router services (e.g., inetd, HTTP, DNS, and UPnP) via long JSON data for wireless wlan_host_2g isolate.
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Analysis
by VulDB Data Team • 03/23/2020
The vulnerability CVE-2018-17009 represents a critical buffer overflow condition affecting TP-Link TL-WR886N router models running specific firmware versions. This issue manifests when authenticated attackers submit excessively long JSON data to the wireless wlan_host_2g isolate parameter, causing service disruptions across multiple router components. The affected devices operate with firmware versions 6.0 2.3.4 and 7.0 1.1.0, making them susceptible to intentional service degradation attacks. The vulnerability stems from inadequate input validation mechanisms within the router's web interface processing logic, specifically in how it handles wireless configuration parameters.
The technical flaw resides in the improper handling of JSON data structures within the router's internal processing functions. When the system receives malformed or oversized JSON payloads targeting the wlan_host_2g isolate functionality, it fails to perform adequate bounds checking before attempting to parse and process the input. This deficiency creates a classic buffer overflow scenario where the system attempts to write data beyond allocated memory boundaries. The vulnerability operates at the application layer and affects the router's inetd service, HTTP server, DNS resolver, and UPnP functionality, demonstrating the cascading impact of a single input validation failure. The issue aligns with CWE-121, which describes heap-based buffer overflow conditions, and CWE-122, covering stack-based buffer overflow scenarios, though the specific implementation suggests heap corruption due to JSON parsing operations.
The operational impact of this vulnerability extends beyond simple service disruption to potentially enable more sophisticated attack vectors. When router services crash, attackers can leverage this condition to create denial of service scenarios that may persist until manual intervention occurs. The affected services include inetd, which typically manages network daemon processes, HTTP servers that handle web-based administration, DNS services for local name resolution, and UPnP functionality for device discovery and port mapping. This comprehensive service disruption can effectively isolate the router from network management and compromise its ability to maintain network connectivity. The vulnerability demonstrates characteristics consistent with ATT&CK technique T1499.001, which covers network disruption attacks, and T1566.002, involving spearphishing with social engineering. The authenticated nature of the attack means that adversaries must first gain access to legitimate administrative credentials, though this requirement does not prevent exploitation as administrative access is often obtained through other means.
Mitigation strategies for CVE-2018-17009 should prioritize immediate firmware updates from TP-Link to address the root cause of the buffer overflow. Network administrators should also implement network segmentation to limit the impact of potential service disruptions and establish monitoring protocols to detect unusual service behavior patterns. Additional defensive measures include disabling unnecessary services such as UPnP when not required, implementing strict access controls for administrative interfaces, and maintaining detailed logs of configuration changes. The vulnerability highlights the importance of robust input validation and memory management practices in embedded systems, particularly those handling user-supplied data through web interfaces. Organizations should also consider implementing intrusion detection systems to monitor for unusual JSON data patterns and establish incident response procedures for handling service disruption events. Regular security assessments of network infrastructure components are essential to identify similar vulnerabilities in other embedded devices and ensure comprehensive protection against similar buffer overflow conditions.