CVE-2018-17006 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 firewall lan_manage mac2.
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Analysis
by VulDB Data Team • 03/23/2020
The vulnerability CVE-2018-17006 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 in the router's handling of JSON data within the firewall management interface. This issue stems from inadequate input validation mechanisms that fail to properly sanitize or limit the length of JSON payloads submitted through the lan_manage mac2 parameter, creating a potential denial of service condition that can disrupt core network services.
The technical implementation of this vulnerability involves a buffer overflow or memory corruption scenario where authenticated attackers can submit excessively long JSON data to the firewall management endpoint. When the router processes this malformed input, the system's internal parsing routines encounter memory boundaries that are not properly enforced, leading to service crashes of critical components including inetd, HTTP servers, DNS services, and UPnP functionality. This represents a classic example of improper input validation that maps to CWE-121, which describes stack-based buffer overflow conditions.
From an operational impact perspective, this vulnerability allows authenticated attackers to perform denial of service attacks against the affected router, effectively disrupting network connectivity and services for legitimate users. The attack requires only authenticated access to the router's administrative interface, which can be achieved through credential compromise or social engineering tactics. The disruption affects fundamental network services that many users rely upon, making this a particularly concerning vulnerability for both home and small office environments where such routers are commonly deployed.
The attack vector aligns with ATT&CK technique T1499.004, which covers network disruption through service availability attacks, and demonstrates how authenticated access can be leveraged to cause operational damage. The vulnerability's exploitation is relatively straightforward since it requires only that an attacker possess valid administrative credentials to submit malicious JSON data. This makes it particularly dangerous in environments where administrative credentials might be weak or compromised through phishing attacks.
Mitigation strategies should focus on firmware updates provided by TP-Link to address the input validation flaws in the router's management interface. Organizations and individuals should implement strict credential management practices including strong password policies, multi-factor authentication, and regular credential rotation. Network segmentation and monitoring can help detect unauthorized access attempts, while regular firmware updates ensure that known vulnerabilities are patched. The vulnerability also underscores the importance of input sanitization and bounds checking in embedded systems, particularly those handling user-supplied data in network infrastructure devices.
This vulnerability serves as a reminder of the critical security considerations for embedded network devices, where resource constraints often lead to insufficient input validation and error handling mechanisms. The affected devices represent a common class of consumer-grade routers that may lack robust security features typically found in enterprise-grade equipment, making them attractive targets for attackers seeking to exploit basic implementation flaws. The combination of authenticated access requirements with severe operational impact makes this vulnerability particularly dangerous in environments where router security is not regularly assessed or maintained.
The broader implications extend beyond simple service disruption to highlight potential escalation pathways where attackers might use such vulnerabilities as stepping stones to more comprehensive network compromise. While the immediate impact is denial of service, the vulnerability demonstrates how seemingly minor input validation issues can result in significant operational consequences. Security practitioners should consider this vulnerability when assessing embedded device security postures and implementing network monitoring solutions to detect anomalous administrative access patterns.