CVE-2018-17004 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 wlan_access name.
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Analysis
by VulDB Data Team • 03/23/2020
The vulnerability identified as CVE-2018-17004 affects TP-Link TL-WR886N routers running firmware versions 6.0 2.3.4 and 7.0 1.1.0, representing a critical security flaw that enables authenticated attackers to disrupt essential router services through crafted JSON data manipulation. This issue stems from insufficient input validation within the wlan_access name parameter, which is processed by the router's internal services including inetd, HTTP, DNS, and UPnP daemons. The vulnerability operates by exploiting a buffer overflow condition or memory corruption scenario that occurs when the device processes excessively long JSON payloads designated for the wlan_access name field, ultimately leading to service crashes and potential denial of service conditions.
The technical implementation of this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-787, which addresses out-of-bounds write operations. Attackers with valid authentication credentials can leverage this weakness by sending specially crafted JSON data containing extended strings to the wlan_access name parameter, causing the affected services to terminate unexpectedly. The impact extends beyond simple service disruption as the compromised services may include critical network functions such as the HTTP web interface, internet connectivity management through inetd, DNS resolution capabilities, and universal plug and play functionality that enables device discovery and communication within home networks.
From an operational perspective, this vulnerability creates significant security implications for users who may not realize their network devices are compromised until services become unavailable. The authenticated nature of the attack means that only users with legitimate credentials can exploit this weakness, but this still represents a concerning exposure since it allows for service disruption without requiring elevated privileges or complex exploitation techniques. The attack vector specifically targets the router's configuration management interfaces where JSON data is processed, making it particularly dangerous as it can affect multiple services simultaneously and potentially create cascading failures within the network infrastructure.
The exploitation of this vulnerability demonstrates a pattern consistent with ATT&CK technique T1499.001, which involves network disruption through service availability attacks, and T1078, which covers legitimate credentials usage for persistence and access. Network administrators should implement immediate mitigations including firmware updates to the latest available versions from TP-Link, which typically address the input validation issues by implementing proper bounds checking and sanitization of JSON data. Additionally, network segmentation strategies and monitoring of service availability can help detect exploitation attempts, while regular firmware updates and credential management practices should be enforced to prevent unauthorized access to router management interfaces. The vulnerability also highlights the importance of secure coding practices in embedded systems and the necessity of input validation across all user-facing parameters within network infrastructure devices to prevent similar issues from occurring in other vendor products.