CVE-2024-2854: Tenda AC18 Firmware RCE Vulnerability

CVE-2024-2854 Overview

CVE-2024-2854 is an operating system (OS) command injection vulnerability in the Tenda AC18 wireless router running firmware version 15.03.05.05. The flaw resides in the formSetSambaConf function within /goform/setsambacfg, where the usbName argument is passed to a shell context without proper sanitization. Remote attackers can inject arbitrary OS commands through this parameter and execute them with the privileges of the web management process. The issue is tracked as VulDB identifier VDB-257778 and is classified under [CWE-78]. According to the disclosure record, the vendor did not respond to the early notification.

Critical Impact

Unauthenticated remote attackers can execute arbitrary operating system commands on affected Tenda AC18 routers, leading to full device compromise.

Affected Products

• Tenda AC18 router (hardware)
• Tenda AC18 firmware version 15.03.05.05
• Deployments exposing the web management interface (/goform/setsambacfg) to untrusted networks

Discovery Timeline

• 2024-03-24 - CVE-2024-2854 published to the National Vulnerability Database (NVD)
• 2024-11-21 - Last updated in the NVD database

Technical Details for CVE-2024-2854

Vulnerability Analysis

The vulnerability is an OS command injection [CWE-78] in the Samba configuration handler of the Tenda AC18 router. The HTTP endpoint /goform/setsambacfg invokes the internal formSetSambaConf function, which processes user-supplied parameters used to configure Samba file sharing for an attached USB device. The usbName parameter is incorporated into a shell command construction without input validation or argument quoting. An attacker submitting crafted shell metacharacters in usbName causes the router to execute attacker-controlled commands in addition to the intended configuration command.

Exploitation requires network access to the router's management interface but no authentication or user interaction, and impacts confidentiality, integrity, and availability. The Exploit Prediction Scoring System (EPSS) places this issue in the 81st percentile, indicating elevated likelihood of exploitation activity relative to the broader CVE population.

Root Cause

The root cause is unsafe concatenation of attacker-controlled input into a shell command. The formSetSambaConf handler builds a command string that embeds the usbName value and passes it to a system shell helper such as system() or popen(). Because the firmware does not filter shell metacharacters (;, |, &, backticks, $()), arbitrary commands can be appended to the legitimate Samba configuration command.

Attack Vector

The attack vector is network-based. An attacker sends a crafted HTTP POST request to /goform/setsambacfg on the router's management interface, supplying a malicious usbName value containing shell metacharacters followed by the desired command. The router parses the request, calls formSetSambaConf, and executes the injected payload. Where the management interface is reachable from the WAN side, exploitation can occur from the public internet. Where it is restricted to the LAN, an attacker on the local network or a victim browser performing cross-site requests can reach the endpoint.

No verified proof-of-concept code is referenced in the enriched data. The vulnerability mechanism is described in the public GitHub Vulnerability Documentation and the VulDB entry #257778.

Detection Methods for CVE-2024-2854

Indicators of Compromise

• HTTP POST requests to /goform/setsambacfg containing shell metacharacters (;, |, &, `, $() within the usbName parameter.
• Unexpected outbound connections from the router to attacker-controlled hosts following Samba configuration changes.
• New or modified processes on the router, persistence entries in startup scripts, or unexplained changes to /etc or NVRAM-backed configuration.

Detection Strategies

• Inspect HTTP traffic destined to the router management interface and alert on requests to /goform/setsambacfg originating from untrusted segments.
• Apply network intrusion detection signatures that match shell metacharacters in usbName POST bodies.
• Correlate router configuration changes with subsequent anomalous DNS or outbound TCP traffic from the device's management VLAN.

Monitoring Recommendations

• Forward router system logs and HTTP access logs to a central log platform and retain them for incident review.
• Monitor for management-plane access from non-administrative source addresses, especially WAN-side hits.
• Baseline normal Samba and USB-sharing configuration activity so that unexpected formSetSambaConf invocations stand out.

How to Mitigate CVE-2024-2854

Immediate Actions Required

• Disable the Samba/USB file-sharing feature on the Tenda AC18 if it is not required for business operations.
• Restrict access to the router's web management interface so that it is unreachable from the WAN and limited to a dedicated management network on the LAN.
• Change administrative credentials and audit configured users on the device after applying network controls.

Patch Information

At the time of NVD publication and last modification (2024-11-21), no vendor advisory or fixed firmware version is listed in the enriched data. The disclosure record states that Tenda was contacted but did not respond. Operators should monitor the Tenda support site for a firmware release that addresses formSetSambaConf input handling and apply it once available.

Workarounds

• Block external access to TCP ports used by the router's HTTP/HTTPS management interface at the upstream firewall.
• Place the AC18 behind a segmented management VLAN and require administrators to connect through a jump host or VPN.
• If the device is end-of-life or no patch becomes available, replace it with a supported router model that receives current security updates.

# Configuration example: restrict access to the Tenda AC18 management interface
# Replace 192.0.2.10 with the administrator workstation address
# and 198.51.100.1 with the router LAN IP.
iptables -I FORWARD -p tcp -d 198.51.100.1 --dport 80  -s 192.0.2.10 -j ACCEPT
iptables -I FORWARD -p tcp -d 198.51.100.1 --dport 443 -s 192.0.2.10 -j ACCEPT
iptables -I FORWARD -p tcp -d 198.51.100.1 --dport 80  -j DROP
iptables -I FORWARD -p tcp -d 198.51.100.1 --dport 443 -j DROP