CVE-2021-46314 in DIR-846
Summary
by MITRE • 02/18/2022
A Remote Command Execution (RCE) vulnerability exists in HNAP1/control/SetNetworkTomographySettings.php of D-Link Router DIR-846 DIR846A1_FW100A43.bin and DIR846enFW100A53DLA-Retail.bin because backticks can be used for command injection when judging whether it is a reasonable domain name.
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Analysis
by VulDB Data Team • 02/19/2022
The vulnerability CVE-2021-46314 represents a critical remote command execution flaw discovered in D-Link DIR-846 routers running specific firmware versions. This vulnerability resides within the HNAP1/control/SetNetworkTomographySettings.php component of the router's web interface, making it accessible through the device's HTTP management interface. The flaw stems from inadequate input validation mechanisms that fail to properly sanitize user-supplied domain name parameters, creating a pathway for malicious actors to inject arbitrary commands into the system.
The technical implementation of this vulnerability leverages the backtick character injection technique, which is a well-documented method for command injection in Unix-like systems where backticks are interpreted as command substitution operators. When the router processes network tomography settings, it performs domain name validation but does not adequately filter or escape special characters including backticks that could be used to execute system commands. This allows an attacker to append malicious commands following the backtick operator, effectively bypassing the intended validation logic and executing arbitrary code with the privileges of the web server process.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with complete remote control over the affected router. Successful exploitation could enable adversaries to gain persistent access to the network, modify routing configurations, intercept network traffic, or use the compromised device as a pivot point for attacking other systems within the local network. The vulnerability affects multiple firmware versions including DIR846A1_FW100A43.bin and DIR846enFW100A53DLA-Retail.bin, indicating a widespread issue across affected D-Link products and potentially exposing numerous network endpoints to attack. This type of vulnerability falls under CWE-77 and CWE-94 categories, representing command injection and code injection weaknesses that are classified as high-severity threats in cybersecurity frameworks.
Mitigation strategies for this vulnerability should include immediate firmware updates from D-Link to address the command injection flaw, network segmentation to limit access to router management interfaces, and implementation of network monitoring to detect suspicious command execution patterns. Organizations should also consider disabling unnecessary web management interfaces, implementing strict access controls, and regularly auditing router configurations for unauthorized modifications. The vulnerability aligns with ATT&CK technique T1059.001 for command and scripting interpreter, making it a significant concern for enterprise security teams. Additionally, network administrators should deploy intrusion detection systems capable of identifying command injection attempts and maintain comprehensive network logging to facilitate forensic analysis in case of successful exploitation attempts.