CVE-2025-4737

Executive Summary

CVE-2025-4737 identifies an insufficient encryption vulnerability in the Transsion mobile application com.transsion.aivoiceassistant. This flaw may lead to the leakage of sensitive information due to weak or missing encryption mechanisms within the app’s data handling processes. The vulnerability is classified under CWE-311 (Missing Encryption of Sensitive Data), indicating that the application fails to properly encrypt sensitive data in transit or at rest. As of the latest intelligence, no public proof-of-concept (PoC) exploit, patch, or vendor advisory has been released. The EPSS score is 0.0%, suggesting low exploitation activity in the wild, but the risk remains significant for affected users.

Supply Chain & Package Security

This vulnerability is specific to the Android mobile application com.transsion.aivoiceassistant, which is distributed through official app stores and potentially pre-installed on Transsion devices. No open-source package (NPM, PyPI, Go, Ruby) is involved. The risk is primarily to end-users of Transsion devices, where the app may have elevated privileges or access to sensitive data like contacts, messages, or voice recordings.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which is likely a placeholder or unassigned value. Based on the vulnerability description (insufficient encryption leading to sensitive information leakage), a realistic CVSS v3.1 vector would be:

• Attack Vector (AV): Local (L) – requires access to the device or network traffic interception.
• Attack Complexity (AC): Low (L) – weak encryption is easily bypassed.
• Privileges Required (PR): None (N) – no special privileges needed to exploit.
• User Interaction (UI): None (N) – exploitation does not require user action.
• Scope (S): Unchanged (U) – the vulnerability affects only the app’s data.
• Confidentiality (C): High (H) – sensitive data is exposed.
• Integrity (I): None (N) – data integrity is not directly impacted.
• Availability (A): None (N) – availability is not affected.

Estimated CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Estimated Base Score: 6.2 (Medium)

Threat Level: Medium – Exploitation requires local access or network proximity, but the impact on confidentiality is high.

Deep Dive & Mechanics

The vulnerability resides in the Transsion AI Voice Assistant application (com.transsion.aivoiceassistant). The app likely handles sensitive user data such as voice recordings, personal preferences, contacts, or authentication tokens. Insufficient encryption means that data is either transmitted over the network without TLS, stored locally without encryption, or uses weak cryptographic algorithms (e.g., base64 encoding, XOR, or hardcoded keys).

Potential Attack Vectors:

1. Network Interception: If the app communicates with backend servers over HTTP or uses weak TLS configurations, an attacker on the same network (e.g., public Wi-Fi) can intercept sensitive data.
2. Local Data Extraction: If the app stores data in plaintext or with weak encryption in the device’s internal storage or shared preferences, a malicious app with storage permissions or physical access can extract it.
3. Man-in-the-Middle (MitM): Lack of certificate pinning allows attackers to intercept traffic using a rogue CA certificate.

Technical Details:

• The app may use SharedPreferences or SQLite databases without encryption.
• Network requests may use HttpURLConnection instead of HttpsURLConnection.
• Hardcoded encryption keys or IVs in the APK can be reverse-engineered.

Vulnerable vs. Patched Code

Since no patch is available, we can only hypothesize the vulnerable code pattern and the expected fix.

Vulnerable Code Example (Java/Android):

// Vulnerable: Storing sensitive data without encryption
SharedPreferences prefs = getSharedPreferences("user_data", MODE_PRIVATE);
prefs.edit().putString("auth_token", token).apply();

// Vulnerable: Sending data over HTTP
URL url = new URL("http://api.transsion.com/voice");
HttpURLConnection conn = (HttpURLConnection) url.openConnection();

Patched Code Example (Expected Fix):

// Patched: Encrypt data before storing
EncryptedSharedPreferences prefs = EncryptedSharedPreferences.create(
    "user_data",
    MasterKey.DEFAULT_MASTER_KEY_ALIAS,
    context,
    EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
    EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
);
prefs.edit().putString("auth_token", encryptedToken).apply();

// Patched: Use HTTPS with certificate pinning
HttpsURLConnection conn = (HttpsURLConnection) new URL("https://api.transsion.com/voice").openConnection();
conn.setSSLSocketFactory(sslContext.getSocketFactory());

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• Android device with the vulnerable app installed (or emulator).
• Network access to intercept traffic (e.g., using a proxy like Burp Suite).
• ADB (Android Debug Bridge) for local data extraction.

Steps:

1. Network Interception:

   • Set up a Wi-Fi hotspot with a rogue access point or use ARP spoofing.
   • Configure Burp Suite as a proxy and install its CA certificate on the device.
   • Launch the app and perform actions (e.g., voice commands, login).
   • Monitor HTTP traffic for unencrypted sensitive data.

2. Local Data Extraction:

   • Connect the device via ADB.
   • Run adb shell and navigate to the app’s data directory:

     adb shell
     run-as com.transsion.aivoiceassistant
     cat /data/data/com.transsion.aivoiceassistant/shared_prefs/*.xml
     

   • Look for plaintext tokens, passwords, or personal data.

3. Reverse Engineering:

   • Decompile the APK using apktool or jadx.
   • Search for hardcoded keys or weak encryption algorithms:

     apktool d com.transsion.aivoiceassistant.apk
     grep -r "AES\|DES\|Base64\|encrypt" ./smali/
     

Exploit Code (Conceptual):

# Python script to decrypt intercepted data (if weak encryption is found)
import base64
from Crypto.Cipher import AES

# Example: Hardcoded key found in APK
key = b'TranssionSecret!'
cipher = AES.new(key, AES.MODE_ECB)
encrypted_data = base64.b64decode(intercepted_token)
plaintext = cipher.decrypt(encrypted_data)
print(plaintext)

Blue Team (Defensive)

Detection:

• Monitor network traffic for connections to Transsion domains over HTTP.
• Use mobile device management (MDM) to enforce VPN and certificate pinning.
• Scan for the app version and check for insecure storage patterns.

Mitigation:

• If possible, uninstall or disable the app until a patch is released.
• Use a firewall app to block the app’s network access.
• Educate users to avoid using the app on untrusted networks.

Indicators of Compromise (IOCs)

• Application Package Name: com.transsion.aivoiceassistant
• Network Domains (Suspected):
  • api.transsion.com
  • voice.transsion.com
• File Paths (Local Storage):
  • /data/data/com.transsion.aivoiceassistant/shared_prefs/
  • /data/data/com.transsion.aivoiceassistant/databases/
• Network Traffic Patterns:
  • HTTP requests to domains without TLS.
  • Base64-encoded strings in HTTP headers or bodies.
• Registry/Config Keys:
  • auth_token
  • user_credentials
  • voice_data

Detection Engineering

YARA Rule

rule CVE_2025_4737_Transsion_AIVoiceAssistant {
    meta:
        description = "Detects Transsion AI Voice Assistant APK with insufficient encryption"
        author = "Valters IT"
        date = "2025-04-14"
        cve = "CVE-2025-4737"
    strings:
        $http_url = "http://" ascii wide nocase
        $shared_prefs = "SharedPreferences" ascii wide
        $plaintext_store = "putString" ascii wide
        $weak_crypto = "AES/ECB" ascii wide
    condition:
        (uint16(0) == 0x4B50) and  // PK zip header (APK)
        (1 of ($http_url, $shared_prefs, $plaintext_store, $weak_crypto))
}

Sigma Rule

title: CVE-2025-4737 - Transsion AI Voice Assistant Insufficient Encryption
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects network traffic from com.transsion.aivoiceassistant using HTTP instead of HTTPS
author: Valters IT
date: 2025-04-14
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Image|endswith: 'com.transsion.aivoiceassistant'
        DestinationPort: 80
    condition: selection
falsepositives:
    - Legitimate HTTP traffic if app uses mixed content
level: medium

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET 80 (msg:"CVE-2025-4737 - Transsion AI Voice Assistant HTTP Traffic"; flow:to_server,established; content:"com.transsion.aivoiceassistant"; nocase; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the App: If possible, disable or uninstall com.transsion.aivoiceassistant until a patch is released.
2. Network Controls: Block outbound HTTP traffic from the app using a firewall or MDM policy.
3. User Awareness: Advise users to avoid using the app on public Wi-Fi and to monitor for unusual data usage.

Long-Term Fixes (Vendor):

• Implement strong encryption (AES-256-GCM) for all stored sensitive data.
• Enforce HTTPS with certificate pinning for all network communications.
• Conduct a security audit of the app’s cryptographic implementations.

Detection:

• Deploy the provided YARA, Sigma, and Suricata rules to monitor for exploitation attempts.
• Regularly scan devices for the presence of the vulnerable app version.

Valters IT
Securing Digital Frontiers