CVE-2019-8312 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 SetSysLogSettings 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-2019-8312 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 Administration Protocol) implementation, specifically in the SetSysLogSettings API function where unvalidated user input is directly passed to system commands without proper sanitization. The flaw allows attackers to inject malicious shell commands through crafted HTTP POST requests targeting the /HNAP1 endpoint, making it particularly dangerous as it can be exploited remotely without authentication. The vulnerability stems from improper input validation and sanitization practices within the device's web administration interface, creating a direct pathway for arbitrary command execution on the underlying operating system.
The technical exploitation of this vulnerability follows a well-defined pattern that aligns with CWE-77 and CWE-94 categories, representing command injection and code injection weaknesses respectively. Attackers can manipulate the IPAddress field within the SetSysLogSettings API call to inject shell metacharacters such as semicolons, ampersands, or backticks that get processed by the twsystem function. This function appears to directly execute system commands using user-supplied parameters without adequate input filtering or command escaping mechanisms. The vulnerability's impact is amplified by the fact that the affected device operates with root privileges, meaning successful exploitation grants complete control over the router's operating system, including access to network configuration, user credentials, and potential lateral movement capabilities within the local network. The attack vector leverages the HNAP protocol's design, which is commonly used for device management and configuration, making it an attractive target for attackers seeking persistent access to network infrastructure.
The operational impact of CVE-2019-8312 extends beyond simple remote code execution, creating significant risks for network security and infrastructure integrity. Once exploited, attackers can establish persistent backdoors, modify network settings, intercept traffic, or use the compromised device as a pivot point for attacking other systems within the local network. The vulnerability's remote nature means that attackers can exploit it from anywhere on the internet without requiring physical access or local network presence. This characteristic makes the flaw particularly concerning for enterprise environments where D-Link routers may be exposed to external networks or used in scenarios where network segmentation is inadequate. The vulnerability also demonstrates poor security practices in embedded device development, particularly regarding input validation and secure coding practices. According to ATT&CK framework, this vulnerability maps to T1059.001 (Command and Scripting Interpreter: PowerShell) and T1068 (Exploitation for Privilege Escalation) techniques, as attackers can leverage the root shell access for further system compromise and privilege escalation within the network environment.
Mitigation strategies for CVE-2019-8312 should prioritize immediate firmware updates from D-Link, as the vendor has released patches addressing this specific vulnerability. Organizations should implement network segmentation to isolate affected devices from critical network segments and consider disabling unnecessary HNAP services or API endpoints when not required. Network monitoring solutions should be configured to detect unusual patterns in HNAP traffic, particularly POST requests containing shell metacharacters or unexpected command sequences. Device hardening measures include disabling remote management features when possible, implementing strong authentication mechanisms, and regularly reviewing device configurations for unauthorized changes. Security teams should also consider deploying intrusion detection systems that can identify exploitation attempts targeting known vulnerabilities in network devices. The vulnerability serves as a reminder of the importance of secure coding practices in embedded systems and the necessity of regular security assessments for network infrastructure devices. Organizations should also implement comprehensive vulnerability management processes that include regular scanning for similar command injection vulnerabilities in other network equipment and embedded systems throughout their infrastructure.