CVE-2022-37056: D-Link GO-RT-AC750 RCE Vulnerability

CVE-2022-37056 Overview

CVE-2022-37056 is a command injection vulnerability affecting D-Link GO-RT-AC750 routers. The vulnerability exists in the /cgibin endpoint through the hnap_main interface, allowing remote attackers to execute arbitrary system commands on the affected device. This vulnerability impacts both hardware revisions (A and B) of the GO-RT-AC750 router with firmware versions GORTAC750_revA_v101b03 and GO-RT-AC750_revB_FWv200b02.

Critical Impact

This command injection vulnerability allows unauthenticated remote attackers to gain complete control over vulnerable D-Link GO-RT-AC750 routers, potentially compromising the entire network infrastructure connected to the device.

Affected Products

• D-Link GO-RT-AC750 Firmware version 1.01b03 (Revision A)
• D-Link GO-RT-AC750 Firmware version 2.00b02 (Revision B)
• D-Link GO-RT-AC750 Hardware (Revision A and Revision B)

Discovery Timeline

• August 28, 2022 - CVE-2022-37056 published to NVD
• December 9, 2025 - Last updated in NVD database

Technical Details for CVE-2022-37056

Vulnerability Analysis

This vulnerability is classified as CWE-78 (OS Command Injection), a dangerous flaw that occurs when an application passes unsanitized user-controlled input directly to system shell commands. In the case of CVE-2022-37056, the D-Link GO-RT-AC750 router's web management interface fails to properly validate and sanitize input received through the HNAP (Home Network Administration Protocol) interface accessible via /cgibin.

The HNAP protocol is commonly used in consumer routers for management tasks. When user-supplied data reaches the hnap_main handler without proper input validation, attackers can inject shell metacharacters and arbitrary commands that are then executed with the privileges of the web server process, typically running as root on embedded devices.

Root Cause

The root cause of CVE-2022-37056 lies in the insufficient input validation within the HNAP request handler. The firmware fails to sanitize special characters such as semicolons (;), pipes (|), backticks (`), and other shell metacharacters before incorporating user input into system commands. This improper input validation allows attackers to break out of the intended command context and execute arbitrary commands on the underlying operating system.

Attack Vector

The attack vector for this vulnerability is network-based and requires no authentication or user interaction. An attacker with network access to the router's management interface can craft malicious HNAP requests targeting the /cgibin endpoint. The hnap_main function processes these requests and, due to the lack of input sanitization, allows command injection.

Successful exploitation enables attackers to execute arbitrary commands with root privileges, potentially allowing them to:

• Modify router configuration and DNS settings
• Intercept and redirect network traffic
• Install persistent backdoors
• Use the compromised router as a pivot point for further attacks
• Recruit the device into a botnet

The vulnerability mechanism involves crafting malicious SOAP-formatted HNAP requests containing shell metacharacters in parameter values. When these parameters are processed by the CGI handler without sanitization, the injected commands are executed on the underlying Linux system. For detailed technical information, refer to the D-Link Security Advisory SAP10308.

Detection Methods for CVE-2022-37056

Indicators of Compromise

• Unexpected outbound connections from the router to suspicious IP addresses or command-and-control servers
• Modified router configuration files, DNS settings, or firewall rules without administrator action
• Unusual processes running on the router identified through diagnostic interfaces
• Increased CPU or memory utilization on the router indicating potential malicious activity
• Suspicious entries in router logs showing malformed HNAP requests to /cgibin

Detection Strategies

• Monitor network traffic for anomalous HNAP requests containing shell metacharacters such as ;, |, &, or backticks
• Implement intrusion detection signatures to identify command injection patterns in HTTP POST requests to /cgibin endpoints
• Deploy network behavior analysis to detect unusual traffic patterns originating from router devices
• Review HTTP access logs for requests to hnap_main with suspicious parameter values

Monitoring Recommendations

• Enable logging on all network perimeter devices and centralize logs for analysis
• Implement network segmentation to isolate IoT and router management interfaces from critical network segments
• Deploy network monitoring solutions to track traffic patterns from consumer networking devices
• Establish baseline behavior for router network communications and alert on deviations

How to Mitigate CVE-2022-37056

Immediate Actions Required

• Check if your D-Link GO-RT-AC750 router is running firmware versions 1.01b03 (Rev A) or 2.00b02 (Rev B) and prioritize remediation
• Disable remote management access to the router's web interface if not required
• Restrict access to the router's management interface to trusted IP addresses only
• Consider placing vulnerable routers behind a firewall that can filter malicious HNAP requests
• If no patch is available, evaluate replacing the device with a supported alternative

Patch Information

D-Link has acknowledged this vulnerability. Organizations and users should consult the D-Link Security Advisory SAP10308 for the latest patch availability and firmware update instructions. Additionally, check the D-Link Security Bulletin page for any updated guidance or newer firmware releases that address this vulnerability.

Workarounds

• Disable HNAP protocol functionality if the router's firmware allows this configuration option
• Implement network-level access control lists (ACLs) to restrict access to the router's management ports (typically port 80/443)
• Use a separate VLAN for router management to limit exposure to potential attackers
• Deploy a web application firewall (WAF) or intrusion prevention system (IPS) in front of the router to filter malicious requests

# Example: Block external access to router management interface using iptables on upstream firewall
iptables -A FORWARD -d <router_ip> -p tcp --dport 80 -j DROP
iptables -A FORWARD -d <router_ip> -p tcp --dport 443 -j DROP