CVE-2025-11633

Executive Summary

CVE-2025-11633 identifies a critical security vulnerability in Tomofun Furbo 360 and Furbo Mini pet cameras. The flaw resides in the upload_file_to_s3 function within the collect_logs.sh script, which is part of the HTTP Traffic Handler component. The manipulation leads to improper certificate validation (CWE-295), allowing a remote attacker to potentially intercept or manipulate log data uploaded to Amazon S3. The attack is considered to have high complexity and is difficult to exploit. The vendor was contacted but did not respond, and no patch is currently available. This vulnerability poses a significant risk to user privacy and device integrity, as it could enable man-in-the-middle (MITM) attacks on log data.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a firmware-level issue in a proprietary IoT device. The supply chain risk is limited to the device's firmware update mechanism and the trustworthiness of the S3 endpoint used for log uploads.

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:

• Attack Vector (AV): Network (N) – The attack is initiated remotely.
• Attack Complexity (AC): High (H) – Exploitation is difficult and requires specific conditions.
• Privileges Required (PR): None (N) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – The vulnerability affects only the device's log upload.
• Confidentiality (C): High (H) – Potential exposure of sensitive log data.
• Integrity (I): High (H) – Log data could be tampered with.
• Availability (A): None (N) – No impact on availability.

Estimated CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N Estimated Score: 7.4 (High)

Threat Level: High. Although exploitation is complex, the potential for data interception and manipulation in a home security device is severe.

Deep Dive & Mechanics

The vulnerability is in the collect_logs.sh script, which is responsible for collecting and uploading device logs to Amazon S3. The function upload_file_to_s3 is used to perform the upload. The issue is improper certificate validation, meaning the script does not properly verify the SSL/TLS certificate of the S3 endpoint. This allows an attacker to perform a man-in-the-middle (MITM) attack by presenting a fake certificate, intercepting the log data, and potentially modifying it before it reaches the legitimate S3 bucket.

The attack flow:

1. The device initiates an HTTPS connection to the S3 endpoint.
2. Due to improper certificate validation, the device accepts any certificate presented.
3. An attacker on the network (e.g., same Wi-Fi) can intercept the connection using a proxy or ARP spoofing.
4. The attacker captures the log data, which may contain sensitive information such as device status, user activity, or network details.
5. The attacker can also modify the log data before forwarding it to the real S3 bucket, potentially injecting false data or disrupting logging.

The high complexity stems from the need for the attacker to be on the same network and to successfully perform a MITM attack, which requires specific tools and conditions.

Vulnerable vs. Patched Code

Since no patch is available, we can only analyze the vulnerable code pattern. The collect_logs.sh script likely uses a command-line tool like curl or wget to upload files to S3. The vulnerable code might look like:

# Vulnerable: No certificate validation
curl -k -X PUT -T "$logfile" "https://s3.amazonaws.com/bucket/logs/$logfile"

The -k flag in curl disables certificate validation. A patched version would remove this flag and ensure proper certificate validation:

# Patched: Proper certificate validation
curl --cacert /etc/ssl/certs/ca-certificates.crt -X PUT -T "$logfile" "https://s3.amazonaws.com/bucket/logs/$logfile"

Alternatively, the script might use wget with --no-check-certificate. The fix would be to remove that option and ensure the system's CA certificates are used.

Exploitation & Lab Setup

Red Team

Objective: Intercept and manipulate log data from a Furbo device.

Prerequisites:

• A Furbo 360 or Furbo Mini on the same network.
• A machine with Kali Linux or similar.
• Tools: bettercap, mitmproxy, curl, openssl.

Steps:

1. Network Reconnaissance: Identify the Furbo device's IP address using nmap or arp-scan.

   sudo arp-scan --localnet
   

2. ARP Spoofing: Use bettercap to perform ARP spoofing between the Furbo device and the gateway.

   sudo bettercap -eval "set arp.spoof.targets <FURBO_IP>; arp.spoof on"
   

3. MITM Proxy: Set up mitmproxy to intercept HTTPS traffic. Since the device does not validate certificates, you can use a self-signed certificate.

   mitmproxy --mode transparent --listen-port 8080
   

4. Redirect Traffic: Use iptables to redirect HTTP/HTTPS traffic to the proxy.

   sudo iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 443 -j REDIRECT --to-port 8080
   

5. Capture Logs: Monitor the proxy for requests to S3. The log data will be visible in plaintext or as uploaded files.

6. Modify Data: Use mitmproxy scripts to alter the log data before forwarding.

Expected Outcome: The attacker can view and modify log data, potentially injecting false information or exfiltrating sensitive data.

Blue Team

Objective: Detect and prevent exploitation of CVE-2025-11633.

Detection:

• Monitor network traffic for unusual ARP packets (ARP spoofing).
• Look for connections to S3 endpoints with invalid or self-signed certificates.
• Use IDS/IPS rules to detect MITM attacks.

Prevention:

• Isolate IoT devices on a separate VLAN with strict firewall rules.
• Use network segmentation to limit the attack surface.
• Implement certificate pinning on the device (requires firmware update).
• Monitor for unauthorized proxy or redirect rules on the network.

Response:

• If exploitation is detected, disconnect the device from the network.
• Review logs for signs of tampering.
• Contact Tomofun for a firmware update.

Indicators of Compromise (IOCs)

• Network:
  • Unusual ARP replies (ARP spoofing).
  • Connections to S3 endpoints with self-signed certificates.
  • Traffic redirected to a proxy IP (e.g., 192.168.1.100:8080).
• Device:
  • Modified log files with unexpected content.
  • Device logs showing failed certificate validation attempts.
• File:
  • Presence of mitmproxy or bettercap logs on the attacker's machine.
  • Captured log files from the Furbo device.

Detection Engineering

YARA Rule

rule CVE_2025_11633_Furbo_Log_Upload {
    meta:
        description = "Detects vulnerable collect_logs.sh script with improper certificate validation"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-11633"
    strings:
        $curl_insecure = "-k" ascii wide nocase
        $wget_insecure = "--no-check-certificate" ascii wide nocase
        $s3_upload = "upload_file_to_s3" ascii wide nocase
    condition:
        $s3_upload and ($curl_insecure or $wget_insecure)
}

Sigma Rule

title: CVE-2025-11633 Furbo Improper Certificate Validation
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects attempts to exploit improper certificate validation in Tomofun Furbo devices
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-11633
logsource:
    category: network
    product: suricata
detection:
    selection:
        - alert.signature: "ET POLICY Insecure SSL/TLS Connection to S3"
        - alert.signature: "ET SCAN ARP Spoofing Detected"
    condition: selection
falsepositives:
    - Legitimate use of insecure tools for testing
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET 443 (msg:"CVE-2025-11633 Furbo Improper Certificate Validation"; flow:to_server; content:"|16 03|"; depth:2; content:"|01|"; within:1; content:"s3.amazonaws.com"; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Network Segmentation: Place Furbo devices on a separate VLAN with no access to other critical systems.
2. Firewall Rules: Block outbound connections to unknown S3 endpoints or restrict to known IP ranges.
3. Monitor Traffic: Use IDS/IPS to detect MITM attacks and insecure connections.

Long-term Fix:

• Firmware Update: Await a patch from Tomofun that removes the -k flag and implements proper certificate validation.
• Certificate Pinning: Implement certificate pinning in the firmware to prevent MITM attacks.
• Vendor Communication: Continue to pressure Tomofun for a response and patch.

Workaround:

• If possible, disable log upload functionality in the device settings (if available).
• Use a VPN to encrypt traffic from the device to the internet, reducing the risk of MITM.

Valters IT