CVE-2024-13870

Executive Summary

CVE-2024-13870 is an improper access control vulnerability in Bitdefender Box 1 firmware version 1.3.52.928 and below. An unauthenticated attacker within WiFi range can downgrade the device's firmware to an older, potentially vulnerable version of a Bitdefender-signed firmware, provided the device is booted in Recovery Mode. This attack bypasses the intended firmware integrity checks, allowing the installation of a signed but outdated firmware with known vulnerabilities. The CVSS score is 0.0 due to incomplete scoring data, but the actual risk is significant for affected devices.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a physical IoT device (Bitdefender Box 1) and its firmware. The supply chain risk is limited to the device's firmware update mechanism.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Adjacent Network (AV:A) – Requires attacker to be within WiFi range.
• Attack Complexity (AC): Low (AC:L) – No special conditions required beyond Recovery Mode.
• Privileges Required (PR): None (PR:N) – Unauthenticated.
• User Interaction (UI): None (UI:N) – No user action needed.
• Scope (S): Unchanged (S:U) – Affects only the device.
• Confidentiality (C): None (C:N) – No data exposure.
• Integrity (I): High (I:H) – Firmware downgrade compromises integrity.
• Availability (A): High (A:H) – Downgrade can lead to device instability or exploitation.

Threat Level: High. The attack is feasible for an attacker with physical proximity and can lead to full compromise of the device.

Deep Dive & Mechanics

The vulnerability lies in the firmware update mechanism of Bitdefender Box 1. When the device is booted in Recovery Mode, it accepts firmware images signed by Bitdefender without verifying the version number. An attacker can craft a downgrade attack by serving an older, signed firmware image (e.g., version 1.3.52.928 or earlier) to the device. The device's bootloader or update agent does not enforce a minimum version check, allowing the installation of a firmware with known vulnerabilities.

Root Cause: Missing version validation in the recovery update process. The device trusts any Bitdefender-signed firmware, regardless of its version.

Attack Flow:

1. Attacker gains physical proximity to the device (within WiFi range).
2. Attacker forces the device into Recovery Mode (e.g., by power cycling with a specific button sequence).
3. Attacker sets up a rogue WiFi access point or intercepts the update process.
4. Attacker serves a downgraded firmware image (signed by Bitdefender) to the device.
5. Device installs the older firmware, exposing known vulnerabilities.

Vulnerable vs. Patched Code

No code snippets are available for this vulnerability. The vulnerable behavior is in the firmware update logic:

Vulnerable (Recovery Mode):

if (firmware_signed_by_bitdefender(firmware_image)) {
    install_firmware(firmware_image);
}

Patched (Hypothetical):

if (firmware_signed_by_bitdefender(firmware_image) && firmware_version >= MIN_ALLOWED_VERSION) {
    install_firmware(firmware_image);
}

The patch would add a version check to prevent downgrades.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Bitdefender Box 1 device (firmware <= 1.3.52.928)
• Attacker machine with WiFi adapter (e.g., Kali Linux)
• Older signed firmware image (e.g., version 1.3.52.928)

Steps:

1. Boot the Bitdefender Box 1 in Recovery Mode (refer to device manual).
2. Set up a rogue WiFi access point with the same SSID as the device's expected update server.
3. Use a tool like dnsmasq to redirect firmware update requests to your attacker machine.
4. Serve the older firmware image via HTTP:

   python3 -m http.server 80
   

5. Monitor the device logs to confirm downgrade.

Note: No public exploit code is available. This is a conceptual demonstration.

Blue Team

Detection:

• Monitor for unexpected firmware version changes on Bitdefender Box 1 devices.
• Log all firmware update attempts and verify version numbers.
• Use network monitoring to detect rogue WiFi access points.

Prevention:

• Ensure devices are not accessible from untrusted WiFi networks.
• Implement network segmentation for IoT devices.
• Apply vendor patches when available.

Indicators of Compromise (IOCs)

• Firmware Version: Downgrade to version <= 1.3.52.928
• Network Traffic: HTTP requests to unknown IPs for firmware images (e.g., GET /firmware.bin)
• Device Logs: Entries indicating recovery mode boot or firmware downgrade
• WiFi Events: Unexpected access points with SSID matching update server

Detection Engineering

YARA Rule

rule CVE_2024_13870_Firmware_Downgrade {
    meta:
        description = "Detects Bitdefender Box 1 firmware downgrade attempts"
        author = "Valters IT"
        date = "2025-04-17"
        reference = "CVE-2024-13870"
    strings:
        $firmware_header = "BITDEFENDER_FIRMWARE" ascii wide nocase
        $version_string = "1.3.52.928" ascii wide nocase
    condition:
        $firmware_header and $version_string
}

Sigma Rule

title: Bitdefender Box 1 Firmware Downgrade Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects network traffic indicative of firmware downgrade to vulnerable version
author: Valters IT
date: 2025-04-17
logsource:
    category: network_connection
    product: suricata
detection:
    selection:
        dest_port: 80
        http.uri: '/firmware.bin'
        http.host: 'update.bitdefender.com'
    condition: selection
falsepositives:
    - Legitimate firmware updates (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-13870 Bitdefender Box 1 Firmware Downgrade"; flow:to_server; content:"GET"; http_method; content:"/firmware.bin"; http_uri; content:"update.bitdefender.com"; http_host; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable Recovery Mode access from untrusted networks.
2. Monitor for unauthorized firmware changes.
3. Isolate Bitdefender Box 1 devices on a separate VLAN.

Long-term Fix:

• Apply vendor patch when available (expected to enforce version checks in Recovery Mode).
• Upgrade to a supported device model if no patch is released.

Workaround:

• Physically secure the device to prevent unauthorized access to Recovery Mode.
• Use WiFi encryption (WPA3) to limit adjacent network access.

Valters IT
DevSecOps & Cyber Threat Intelligence