CVE-2019-8314 in DIR-878
Summary
by MITRE
An issue was discovered on D-Link DIR-878 devices with firmware 1.12A1. This issue is a Command Injection allowing a remote attacker to execute arbitrary code, and get a root shell. A command Injection vulnerability allows attackers to execute arbitrary OS commands via a crafted /HNAP1 POST request. This occurs when any HNAP API function triggers a call to the system function with untrusted input from the request body for the SetQoSSettings API function, as demonstrated by shell metacharacters in the IPAddress field.
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Analysis
by VulDB Data Team • 07/10/2023
The CVE-2019-8314 vulnerability represents a critical command injection flaw in D-Link DIR-878 routers running firmware version 1.12A1, exposing a significant security risk that allows remote code execution with root privileges. This vulnerability resides within the HNAP (Home Network Access Protocol) implementation of the device, specifically targeting the SetQoSSettings API function where unvalidated user input is directly passed to the system command execution function. The flaw enables attackers to inject malicious shell commands through crafted HTTP POST requests to the /HNAP1 endpoint, creating a pathway for complete system compromise without requiring authentication or physical access to the device.
The technical exploitation mechanism leverages the improper input validation within the HNAP API implementation where the IPAddress field in the SetQoSSettings function fails to sanitize user-supplied data before incorporating it into system commands. This vulnerability directly maps to CWE-77 which defines command injection as the improper handling of externally-provided input that is interpreted as commands by the operating system. When attackers craft malicious payloads containing shell metacharacters such as semicolons, ampersands, or command substitution operators within the IPAddress field, these characters are interpreted by the underlying shell and executed with the privileges of the web server process, typically running with root privileges on the router. The vulnerability demonstrates a classic path-to-root escalation through command injection, where the attacker can execute arbitrary system commands including but not limited to spawning reverse shells, modifying system files, or establishing persistent backdoors.
The operational impact of this vulnerability extends far beyond simple remote code execution, as it provides attackers with complete administrative control over the affected router. Once exploited, the attacker gains root shell access allowing them to manipulate network traffic, modify firewall rules, access connected devices, and potentially use the compromised router as a pivot point for further attacks within the local network. The vulnerability affects the network infrastructure layer by compromising the router's role as a gateway and security boundary, potentially enabling man-in-the-middle attacks, DNS hijacking, or traffic interception. Given that many users operate these routers in home networks with limited security awareness, the exploitation can lead to widespread compromise of connected IoT devices, smart home systems, and personal computers that trust the compromised router for network access.
Mitigation strategies for CVE-2019-8314 should prioritize immediate firmware updates from D-Link, as the vendor has released patches addressing this specific vulnerability. Network administrators should implement network segmentation and firewall rules to restrict access to the HNAP interface, particularly blocking external access to port 80 and 443 on affected devices. The implementation of web application firewalls can help detect and prevent malicious HNAP requests containing command injection patterns. Additionally, security monitoring should include detection of unusual network traffic patterns, particularly those indicative of reverse shell connections or unauthorized system command execution. Organizations should also consider implementing device authentication and authorization mechanisms, as well as regular vulnerability scanning to identify other potentially unpatched devices within their network infrastructure. The vulnerability highlights the importance of input validation and secure coding practices, particularly when dealing with network protocols that accept user input for system operations, aligning with ATT&CK technique T1059.001 for command and scripting interpreter and T1068 for exploit for privilege escalation.