CVE-2018-17005 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 dmz enable.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 03/23/2020
The vulnerability identified as CVE-2018-17005 affects TP-Link TL-WR886N wireless 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 cause denial of service conditions across multiple router services. This vulnerability specifically targets the firewall dmz enable functionality and exploits a buffer handling issue when processing JSON data inputs. The affected services include inetd, HTTP, DNS, and UPnP components that are essential for normal router operation and network connectivity. The vulnerability exists due to insufficient input validation and boundary checking within the router's web interface handling mechanism, creating a condition where malformed JSON data can trigger memory corruption or service crashes.
The technical implementation of this vulnerability stems from a classic buffer overflow condition that occurs when the router's firmware processes JSON payloads for configuring the DMZ (Demilitarized Zone) functionality. When an authenticated user submits a specially crafted JSON payload containing excessive data to the firewall dmz enable parameter, the router's processing routine fails to properly validate the input length or structure. This allows the attacker to overflow the allocated buffer space and potentially cause the target service to terminate unexpectedly. The vulnerability operates at the application layer and requires authentication credentials to exploit, making it less severe than unauthenticated vulnerabilities but still highly concerning for network administrators. According to CWE classification, this represents a CWE-121: Stack-based Buffer Overflow, which is categorized under the broader category of buffer overflow vulnerabilities that can lead to arbitrary code execution or service disruption.
The operational impact of CVE-2018-17005 extends beyond simple service disruption as it can affect multiple critical network functions simultaneously. When the inetd service crashes, it can prevent remote access to the router's administrative interface, while DNS service failures can block local network resolution. The HTTP service crash affects web-based configuration access, and UPnP service disruption can prevent automatic port forwarding configurations from working properly. This cascading effect means that a single attack can compromise multiple network services and potentially isolate the affected router from network management. The vulnerability demonstrates how seemingly minor input validation flaws can have significant operational consequences in network infrastructure devices, particularly when they affect core services that support basic network functionality. From an ATT&CK framework perspective, this vulnerability maps to T1072: Software Deployment Tools and T1499.004: Endpoint Denial of Service, representing a service disruption attack that leverages legitimate administrative interfaces.
Mitigation strategies for CVE-2018-17005 should prioritize firmware updates from TP-Link, as the vendor has likely released patches addressing the buffer overflow condition in subsequent firmware releases. Network administrators should also implement network segmentation to limit the attack surface and ensure that only authorized users have administrative access to the affected devices. Additional protective measures include implementing network monitoring to detect unusual service disruptions or authentication patterns, and establishing strict access controls with strong authentication mechanisms. The vulnerability highlights the importance of input validation and boundary checking in embedded network devices, particularly those handling JSON data structures. Security professionals should consider implementing network access controls that limit administrative access to critical network infrastructure and maintain detailed logs of all configuration changes. Regular firmware updates and vulnerability assessments should be part of standard network security practices to prevent exploitation of known vulnerabilities in network infrastructure devices. Organizations should also consider implementing intrusion detection systems that can identify potential exploitation attempts targeting administrative interfaces of network devices.