CVE-2019-8313 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 twsystem function with untrusted input from the request body for the SetIPv6FirewallSettings API function, as demonstrated by shell metacharacters in the SrcIPv6AddressRangeStart field.
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Analysis
by VulDB Data Team • 07/10/2023
The CVE-2019-8313 vulnerability represents a critical command injection flaw in D-Link DIR-878 routers running firmware version 1.12A1, exposing devices to remote code execution with root privileges. This vulnerability resides within the HNAP (Home Network Access Protocol) implementation, specifically targeting the SetIPv6FirewallSettings API function. The flaw allows remote attackers to inject malicious commands through crafted HTTP POST requests to the /HNAP1 endpoint, effectively bypassing authentication mechanisms and gaining full administrative control over affected devices.
The technical exploitation occurs when the twsystem function processes user input without proper sanitization or validation, particularly in the SrcIPv6AddressRangeStart field of the SetIPv6FirewallSettings API call. This vulnerability falls under CWE-77, which specifically addresses command injection flaws in software systems. The attack vector leverages the HNAP protocol's trust model where legitimate API functions are executed with elevated privileges, making the injection point particularly dangerous. When malicious shell metacharacters are embedded in the SrcIPv6AddressRangeStart parameter, the system processes these inputs directly without proper input validation, enabling arbitrary command execution.
The operational impact of this vulnerability extends far beyond simple remote code execution, as it provides attackers with root shell access to the affected router, enabling complete compromise of the network infrastructure. Attackers can leverage this access to modify firewall rules, redirect traffic, install persistent backdoors, or use the compromised device as a pivot point for attacking other systems within the local network. The vulnerability affects not just individual devices but entire network ecosystems, as routers serve as critical gateways between internal networks and external internet connections. This makes the vulnerability particularly attractive to threat actors seeking to establish persistent access to corporate or residential networks.
Security professionals should implement immediate mitigations including firmware updates from D-Link, network segmentation to isolate affected devices, and monitoring for suspicious HNAP traffic patterns. The vulnerability demonstrates the importance of proper input validation and the principle of least privilege in network device security. Organizations should also consider implementing network access control lists to restrict access to HNAP endpoints and deploy intrusion detection systems capable of identifying malicious command injection attempts. From an ATT&CK framework perspective, this vulnerability maps to techniques involving command and control communications and privilege escalation, with potential lateral movement capabilities through compromised network infrastructure. The flaw underscores the necessity of secure coding practices and comprehensive security testing for network device firmware, particularly in protocols that handle administrative functions without proper input sanitization mechanisms.