Research and project page : https://www.cityfreqs.com.au/pilfer.php

Android microphone checker and jamming application built for AOSP LineageOS.

Application for low battery requirement microphone passive jamming.

Calls audioRecord.startRecording() but DOES NOT READ THE AUDIO BUFFER.

Holds microphone access and should block user apps from gaining focus of microphone.

System telephone calls will override and bump the Jammer from the microphone.

Adds a notification as a reminder for running while in background.

Tested and blocks Google Voice search (user) app. Currently testing Chrome/Omnibox/Assistant app voice blocking.

Active jammer - tone and white noise versions, boost EQ for higher amplitude.

Scan user installed apps for key features, possible NUHF/ACR SDK package name matches and services/receivers running.

Jammers run as an instance of MediaRecorder in a foreground service

Note: Android 11 (API 30) changes to foreground services access to microphone - "while-in-use access" only. see https://developer.android.com/about/versions/11/privacy/foreground-services

Note: Android 12 (API 31) has new concurrent audio capture policy see https://source.android.com/compatibility/12/android-12-cdd#54_audio_recording

Note: APK app bundle will be necessary thing for Google Play Store, apk maintained here for FDroid

Note: Microphone source switch setting from VOICE_COMM to DEFAULT will cause passive jammer to lose concurrent audio focus and stop blocking the microphone

Notes: For Android 12 (https://source.android.com/compatibility/12/android-12-cdd?hl=sr#54_audio_recording) 5.4.5. Concurrent Capture C-1-1 MUST allow concurrent access to microphone by an accessibility service capturing with AudioSource.VOICE_RECOGNITION also: C-1-3 ... another app can capture the voice call if it is a privileged (pre-installed) app with permission CAPTURE_AUDIO_OUTPUT.

TODO:

• Android Dev Partner Outreach complaining about their app(s) crashing from RecognitionService calls

• API 24 (7.0) minimum: add Quick Settings tile service for passive (req: android.permission.BIND_QUICK_SETTINGS_TILE)

• add sdk name print (link to exodus?) to Inspector dialog if nuhf/acr sdk found

• Assistant jammer requires min API 23 (M) for supportsAssist in xml

• background autostart activity for concurrent audio fight via SYSTEM_ALERT_WINDOW permission

• vs AccessibilityService misuse, in Android 10 (does not work in Go version)

• see : https://developer.android.com/guide/components/activities/background-starts

• Android 11/12 changes to concurrent audio

• inconsistent behaviour with widget and jammer service state

• use NotificationCompat classes in services, check for use

• Android 12(S, API31) adds SensorPrivacyManager for device checks as to addition of MIC toggle

Build:

• min API 21 (5.0)
• target API 31 (12.0)
• compiled API 31 (12.0)
• Android Studio 2021.2.1 Patch 1
• Gradle 7.2.1

Changes:

• 4.6.2 (released June 22, 2022)

• bugfix for API 31 notification change

• fdroid metadata folder

• TR syntax fixes

  testing devices

  • EMU : Galaxy Nexus 4.3 (18) (Android Studio AVD, no GApps)
  • EMU : Nexus 4 5.1 (22) (Android Studio AVD, no GApps)
  • EMU : Nexus 5X 7.0 (24) (Android Studio AVD, GApps)
  • EMU : Galaxy Nexus Oreo (27) (Android Studio AVD, GApps)
  • EMU : Pixel 3a 10.0 (29) (Android Studio AVD, GApps)
  • EMU : Pixel 4a 12.0 (31) (Android Studio AVD, GApps)
  • LOW : s4 I9195 (antique) 7.1.2 (25)( /e/ 0.13, Cleanapk)
  • SLO : Mts 5045D (tainted) 7.1.2 (25) (LineageOS 14.1, GApps)
  • MID : Galaxy Tab 2 GT-P5110 (minimal) 7.1.2 (25) (LineageOS 14.1, F-Droid)
  • DEV : s5 G900I (tainted) 10.0 (29)(LineageOS 17.1, GApps)
  • DEV : s5 G900P (useful) 7.1.2 (25) (LineageOS 14.1, F-Droid)
  • PROD: s10 SM-G977B (nominal) 11.0 (30) (LineageOS 18.0, F-Droid)

App screenshots:

• Home fragment

• Inspector fragment

• App Entry Info dialog

• Settings fragment

Active Jammer frequency analysis:

• Active tone, full NUHF range with random scatter drift test

• Active tone, slow speed, limited drift test

• Active tone, carrier and drift limited, fast

• Active jammer (19 kHz carrier, 1000 Hz limit, EQ on) versus ramp-up audio beacon-like signal : scatter jamming demo

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.