CVE-2024-3880: Tenda W30E Firmware RCE Vulnerability

CVE-2024-3880 Overview

CVE-2024-3880 is an operating system command injection vulnerability in the Tenda W30E router running firmware version 1.0.1.25(633). The flaw resides in the formWriteFacMac function handling requests to the /goform/WriteFacMac endpoint. An authenticated remote attacker can manipulate the mac parameter to inject arbitrary shell commands executed by the underlying operating system. The vulnerability is tracked as VDB-260914 and maps to [CWE-78: OS Command Injection]. The exploit technique has been publicly disclosed. The vendor was contacted prior to disclosure but did not respond.

Critical Impact
Successful exploitation grants attackers arbitrary command execution on the router with full compromise of confidentiality, integrity, and availability of the affected device.

Affected Products

Tenda W30E router hardware
Tenda W30E firmware version 1.0.1.25(633)
Deployments exposing the router web management interface to untrusted networks

Discovery Timeline

2024-04-16 - CVE-2024-3880 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2024-3880

Vulnerability Analysis

The vulnerability is an OS command injection flaw in the formWriteFacMac handler within the Tenda W30E web management binary. The handler processes POST requests to /goform/WriteFacMac, a factory-configuration endpoint intended for writing the device MAC address. The mac parameter supplied in the request is passed to a shell command without adequate input sanitization or argument validation. An attacker who can reach the management interface can append shell metacharacters to the mac value, breaking out of the intended command context. The injected commands execute with the privileges of the web server process, typically root on embedded router firmware.

Root Cause

The root cause is improper neutralization of special elements used in an OS command [CWE-78]. The formWriteFacMac function concatenates the user-supplied mac argument directly into a shell command string invoked through a system call. No allowlist validation restricts the value to a well-formed MAC address pattern, and shell metacharacters such as ;, |, &, and backticks are not stripped or escaped before execution.

Attack Vector

Exploitation requires network reachability to the router administration interface and low-privileged authentication. An attacker sends a crafted HTTP request to /goform/WriteFacMac with a mac parameter containing a benign MAC prefix followed by injected shell commands. Because the injected payload runs with elevated privileges, an attacker can pivot to full device takeover, alter routing, deploy IoT malware, or use the device as a foothold into the internal network. Public documentation of the exploitation technique is available in the GitHub IoT Vulnerability Documentation and the VulDB entry.

Detection Methods for CVE-2024-3880

Indicators of Compromise

HTTP POST requests to /goform/WriteFacMac originating from unexpected client IP addresses or automated user agents.
mac parameter values containing shell metacharacters such as ;, |, &, $(, or backticks rather than a valid hexadecimal MAC format.
Unexpected outbound connections from the router to attacker infrastructure following administrative requests.
New processes, cron entries, or startup scripts on the router that were not deployed by administrators.

Detection Strategies

Deploy network monitoring rules that inspect HTTP requests to /goform/WriteFacMac and alert when the mac field fails to match the regex ^[0-9A-Fa-f:]{17}$.
Correlate administrative interface logins with subsequent anomalous outbound traffic from the router management VLAN.
Baseline expected administrative activity and alert on any traffic to factory-configuration endpoints from non-management subnets.

Monitoring Recommendations

Forward router syslog, web server, and authentication logs to a centralized SIEM for correlation and long-term retention.
Monitor for scanning behavior targeting Tenda-specific /goform/ endpoints across the network perimeter.
Track firmware versions across the fleet and alert when devices running 1.0.1.25(633) remain unpatched or exposed.

How to Mitigate CVE-2024-3880

Immediate Actions Required

Restrict access to the router web management interface to trusted management networks only and disable remote WAN administration.
Rotate all administrative credentials on Tenda W30E devices, particularly where default or shared passwords may be in use.
Segment vulnerable devices from sensitive internal assets until a vendor fix is deployed.
Audit devices for signs of prior compromise, including unauthorized configuration changes and unexpected running processes.

Patch Information

No vendor patch has been published for CVE-2024-3880 at the time of writing. The vendor did not respond to disclosure attempts documented in the VulDB submission. Administrators should monitor the Tenda support portal for firmware updates addressing the formWriteFacMac handler and apply them promptly upon release.

Workarounds

Place the router management interface behind a firewall rule that permits access only from a dedicated administrative host.
Disable HTTP/HTTPS management on the WAN interface and require VPN access for remote administration.
Consider replacing the Tenda W30E with a supported device if the vendor does not release a fix, particularly in environments with regulatory exposure.

bash

# Example iptables rule restricting management access to a trusted subnet
iptables -A INPUT -p tcp --dport 80 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j DROP