CVE-2019-8315 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 SetIPv4FirewallSettings API function, as demonstrated by shell metacharacters in the SrcIPv4AddressRangeStart field.
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Analysis
by VulDB Data Team • 07/10/2023
The vulnerability identified as CVE-2019-8315 represents a critical command injection flaw affecting D-Link DIR-878 routers running firmware version 1.12A1. This security weakness resides within the device's HNAP (Home Network Access Protocol) implementation, specifically in the SetIPv4FirewallSettings API function. The vulnerability enables remote attackers to execute arbitrary operating system commands without authentication, potentially leading to complete system compromise and root shell access. The flaw stems from insufficient input validation and sanitization within the twsystem function, which processes user-supplied data from HNAP requests. This critical vulnerability aligns with CWE-77, which categorizes command injection as a severe weakness in software applications that execute operating system commands with untrusted input.
The technical exploitation of this vulnerability occurs through carefully crafted HTTP POST requests to the /HNAP1 endpoint, targeting the SetIPv4FirewallSettings API function. Attackers can manipulate the SrcIPv4AddressRangeStart field within the request body to inject shell metacharacters such as semicolons, ampersands, or pipe characters. When the device processes these malicious inputs through the twsystem function, the operating system executes the injected commands with the highest privileges available, typically root or administrator level access. The vulnerability demonstrates a classic path traversal and command execution pattern where user-controllable data flows directly into system command invocations without proper sanitization or parameterization. This type of vulnerability is particularly dangerous because it requires no authentication and can be exploited from any network location, making it a prime target for automated exploitation tools.
The operational impact of CVE-2019-8315 extends far beyond simple remote code execution, as it provides attackers with complete administrative control over affected devices. Once exploited, attackers can modify firewall rules, access network traffic, install malware, redirect DNS requests, or establish persistent backdoors within the network infrastructure. The vulnerability affects not just individual devices but potentially entire home or small office networks, as compromised routers can serve as entry points for broader network infiltration. This type of vulnerability is categorized under ATT&CK technique T1059.001 for Command and Scripting Interpreter, specifically targeting operating system commands. The implications are particularly severe for enterprise environments where D-Link devices may be deployed without proper network segmentation or monitoring, allowing lateral movement and data exfiltration.
Mitigation strategies for CVE-2019-8315 should include immediate firmware updates from D-Link, which addressed the vulnerability in subsequent releases. Network administrators should implement strict firewall rules to restrict access to the HNAP interface and related ports, particularly blocking external access to TCP port 80 and 443. The principle of least privilege should be applied by disabling unnecessary HNAP functions and restricting API access to trusted internal networks only. Regular network monitoring should include detection of suspicious HNAP traffic patterns and unusual command execution attempts. Additionally, implementing intrusion detection systems with signature-based detection for known command injection patterns can help identify exploitation attempts. Organizations should also consider network segmentation to isolate affected devices and implement network access control to prevent unauthorized access to router management interfaces. The vulnerability highlights the importance of secure coding practices in embedded systems, particularly regarding input validation and command execution handling, aligning with security standards such as OWASP Top Ten and NIST cybersecurity frameworks.