CVE-2025-65295

Executive Summary

CVE-2025-65295 describes a critical firmware verification bypass vulnerability affecting multiple Aqara smart home hubs: Camera Hub G3 (firmware 4.1.9_0027), Hub M2 (firmware 4.3.6_0027), and Hub M3 (firmware 4.3.6_0025). The vulnerability stems from a failure to validate firmware signatures during the update process, combined with the use of outdated cryptographic methods that can be exploited to forge valid signatures. Additionally, the device exposes sensitive information through improperly initialized memory. This allows an attacker with network access to install malicious firmware, effectively gaining persistent control over the hub and potentially the entire smart home ecosystem.

This vulnerability is particularly dangerous because it targets the core update mechanism, which is typically trusted by the device. The lack of proper signature verification means that an attacker can deliver a crafted firmware image that appears legitimate to the device. The use of weak cryptography further lowers the barrier to forging signatures. The information disclosure via uninitialized memory could leak cryptographic keys or other secrets, aiding in the attack.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a firmware-level issue in embedded IoT devices.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which is likely a placeholder or uncalculated. Based on the description, a reasonable CVSS v3.1 vector would be:

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Base Score: 9.8 (Critical)

Breakdown:

• Attack Vector (AV): Network (N) - The attacker can exploit this remotely.
• Attack Complexity (AC): Low (L) - No special conditions are required.
• Privileges Required (PR): None (N) - No authentication needed.
• User Interaction (UI): None (N) - No user action required.
• Scope (S): Unchanged (U) - The vulnerable component is the hub itself.
• Confidentiality (C): High (H) - Full compromise of device secrets and data.
• Integrity (I): High (H) - Attacker can install arbitrary firmware.
• Availability (A): High (H) - Attacker can brick or disrupt the device.

Threat Level: Critical. This vulnerability allows for complete device takeover with no user interaction.

Deep Dive & Mechanics

The vulnerability is a combination of three distinct flaws:

1. Missing Firmware Signature Validation (CWE-347): The device's firmware update process does not properly verify the cryptographic signature of the firmware image before installation. This allows an attacker to present a self-signed or unsigned firmware image that the device will accept and install.

2. Weak Cryptographic Methods: The device uses outdated or weak cryptographic algorithms for signing firmware. This could include algorithms like MD5, SHA-1, or short RSA keys (e.g., 1024-bit or less). These are known to be vulnerable to collision attacks or brute-force key recovery, allowing an attacker to forge a valid signature for a malicious firmware image.

3. Information Exposure Through Uninitialized Memory: During the firmware update process, the device may expose sensitive data (e.g., cryptographic keys, session tokens, or memory contents) from uninitialized memory buffers. This information can be leaked over the network or stored in logs, providing an attacker with the necessary secrets to forge signatures or decrypt communications.

Attack Flow:

1. Reconnaissance: The attacker identifies an Aqara hub on the network (e.g., via Shodan or local network scanning).
2. Information Gathering: The attacker exploits the uninitialized memory leak to extract cryptographic keys or other secrets.
3. Firmware Forging: Using the extracted keys or by exploiting weak cryptography, the attacker creates a malicious firmware image with a forged signature.
4. Delivery: The attacker delivers the malicious firmware to the hub, either by intercepting the update process (e.g., man-in-the-middle) or by tricking the device into connecting to a malicious update server.
5. Installation: The hub accepts the malicious firmware due to the lack of signature validation and installs it.
6. Persistence: The attacker now has persistent, low-level control over the hub, allowing them to monitor traffic, control other smart home devices, or use the hub as a pivot point for further attacks.

Vulnerable vs. Patched Code

Since no patch is available, we can only describe the vulnerable behavior and what a patched version should implement.

Vulnerable Code (Conceptual):

// Firmware update handler - VULNERABLE
void handle_firmware_update(uint8_t *firmware_data, size_t size) {
    // No signature verification performed
    if (validate_firmware_structure(firmware_data, size)) {
        install_firmware(firmware_data, size);
    }
}

bool validate_firmware_structure(uint8_t *data, size_t size) {
    // Only checks basic header, no cryptographic signature
    firmware_header_t *header = (firmware_header_t *)data;
    return (header->magic == EXPECTED_MAGIC && header->size == size);
}

Patched Code (Conceptual):

// Firmware update handler - PATCHED
#include <crypto_lib.h>

void handle_firmware_update(uint8_t *firmware_data, size_t size) {
    // Extract signature from firmware data
    uint8_t *signature = extract_signature(firmware_data, &size);
    uint8_t *payload = extract_payload(firmware_data, &size);
    
    // Verify signature using strong, modern cryptography
    if (verify_signature(payload, size, signature, PUBLIC_KEY)) {
        if (validate_firmware_structure(payload, size)) {
            install_firmware(payload, size);
        }
    } else {
        log_error("Firmware signature verification failed!");
        return;
    }
}

bool verify_signature(uint8_t *data, size_t size, uint8_t *sig, public_key_t *key) {
    // Use ECDSA with P-256 or Ed25519
    return ecdsa_verify(data, size, sig, key);
}

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

1. Hardware: Aqara Camera Hub G3 (firmware 4.1.9_0027), Hub M2 (4.3.6_0027), or Hub M3 (4.3.6_0025).
2. Network: Isolated lab network with the hub connected.
3. Tools:
   • binwalk for firmware extraction and analysis.
   • firmware-mod-kit for modifying firmware.
   • openssl or hashcat for cryptographic attacks.
   • mitmproxy or bettercap for network interception.
   • Custom Python scripts for memory analysis.

Exploitation Steps:

1. Extract Firmware: Obtain a legitimate firmware update file from Aqara's servers.

   binwalk -e firmware.bin
   

2. Analyze Cryptography: Identify the signature algorithm and key size.

   strings firmware.bin | grep -i "rsa\|ecdsa\|sha\|md5"
   

3. Exploit Weak Crypto (if applicable): If SHA-1 is used, generate a collision.

   # Example using sha1collisiondetection
   python3 generate_collision.py -o payload1.bin payload2.bin
   

4. Forge Signature: If keys are leaked or weak, sign a malicious payload.

   # Example using leaked private key
   openssl dgst -sha256 -sign private_key.pem -out malicious.sig malicious.bin
   

5. Craft Malicious Firmware: Combine the forged signature with a malicious payload (e.g., a reverse shell).

   # craft_firmware.py
   import struct
   with open('malicious.bin', 'rb') as f:
       payload = f.read()
   with open('malicious.sig', 'rb') as f:
       signature = f.read()
   header = struct.pack('<II', MAGIC, len(payload) + len(signature))
   with open('malicious_firmware.bin', 'wb') as f:
       f.write(header)
       f.write(signature)
       f.write(payload)
   

6. Deliver Firmware: Use a man-in-the-middle attack to replace the legitimate firmware update with the malicious one.

   # Using mitmproxy
   mitmproxy --mode transparent --listen-port 8080 --script replace_firmware.py
   

7. Trigger Update: Force the hub to check for updates (e.g., via the Aqara app or by sending a crafted network packet).

Blue Team (Defensive)

Detection & Response:

1. Network Monitoring: Monitor for unusual outbound connections from the hub to unknown IPs, especially on ports commonly used for firmware downloads (e.g., 80, 443, 8080).
2. Firmware Integrity: Regularly verify the hash of the installed firmware against known good values.

   sha256sum /path/to/installed_firmware.bin
   

3. Log Analysis: Enable and monitor device logs for failed update attempts or unexpected reboots.
4. Segmentation: Place IoT devices on a separate VLAN with strict firewall rules to limit lateral movement.
5. Vulnerability Scanning: Use tools like nmap with NSE scripts to identify vulnerable Aqara hubs on the network.

   nmap -sV --script http-title -p 80,443 <target>
   

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound connections to IP addresses not associated with Aqara's official update servers (e.g., update.aqara.com).
  • DNS queries for suspicious domains resembling Aqara's update servers (e.g., update.aqara.evil.com).
  • Unusual HTTP requests with large payloads (firmware images) to the hub.
• File IOCs:
  • Firmware images with unexpected hashes.
  • Presence of files in /tmp or /data with suspicious names (e.g., malicious.bin).
• Behavioral IOCs:
  • Unexpected device reboots or factory resets.
  • Changes in device behavior (e.g., lights turning on/off randomly).
  • Unusual network traffic patterns (e.g., constant beaconing to a C2 server).
• Memory IOCs:
  • Leaked cryptographic keys or memory dumps containing sensitive data.

Detection Engineering

YARA Rule

rule Aqara_Firmware_Signature_Bypass {
    meta:
        description = "Detects malicious firmware images targeting Aqara hubs with signature bypass"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-65295"
        hash = "sha256:EXAMPLE_HASH"
    strings:
        $magic = { 41 51 52 41 } // "AQRA" magic bytes
        $weak_crypto = "SHA1" nocase
        $no_sig = "signature" nocase
    condition:
        $magic at 0 and ($weak_crypto or $no_sig)
}

Sigma Rule

title: Aqara Hub Malicious Firmware Update
id: a1b2c3d4-e5f6-7890-abcd-ef1234567890
status: experimental
description: Detects network traffic indicative of a malicious firmware update to an Aqara hub
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-65295
logsource:
    category: network_connection
    product: zeek
detection:
    selection:
        destination.port:
            - 80
            - 443
            - 8080
        destination.ip:
            - "10.0.0.0/8"
            - "172.16.0.0/12"
            - "192.168.0.0/16"
        http.request.body_length: "> 1000000"
    condition: selection
falsepositives:
    - Legitimate firmware updates from Aqara servers
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"Aqara Hub - Potential Malicious Firmware Download"; flow:to_server,established; content:"POST"; http_method; content:"/update"; http_uri; content:"firmware"; http_client_body; pcre:"/^.{1000000,}/R"; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable Automatic Updates: If possible, disable automatic firmware updates on the affected hubs until a patch is available.
2. Network Segmentation: Isolate Aqara hubs on a separate VLAN with strict firewall rules. Block outbound connections to unknown IPs.
3. Monitor Network Traffic: Implement network monitoring to detect unusual traffic patterns to/from the hubs.
4. Firmware Integrity Checks: Regularly verify the integrity of the installed firmware using known good hashes.

Long-Term Fixes:

1. Vendor Patch: Aqara must release a firmware update that:
   • Implements proper cryptographic signature verification using a strong algorithm (e.g., ECDSA with P-256 or Ed25519).
   • Uses a secure boot process to ensure only signed firmware can be loaded.
   • Properly initializes all memory buffers to prevent information leakage.
2. User Action: Apply the vendor patch as soon as it becomes available.
3. Replace Devices: If a patch is not provided, consider replacing the affected hubs with devices from a vendor with a better security track record.

Workarounds:

• Block all outbound traffic from the hubs except to known Aqara update servers.
• Use a firewall to inspect and block firmware update requests that do not originate from Aqara's official IP ranges.

Report generated by Valters IT DevSecOps & CTI Expert System