Audio Capture
Where this stands
No Sigma rule can address this — the telemetry MITRE names has no Sigma logsource behind it.
Sigma has no logsource taxonomy for mobile platforms. MITRE's telemetry here is mobile EDR and device APIs, which no Sigma rule can address.
What the technique is
Adversaries may capture audio to collect information by leveraging standard operating system APIs of a mobile device. Examples of audio information adversaries may target include user conversations, surroundings, phone calls, or other sensitive information. Android and iOS, by default, require that applications request device microphone access from the user. On Android devices, applications must hold the RECORD_AUDIO permission to access the microphone or the CAPTURE_AUDIO_OUTPUT permission to access audio output. Because Android does not allow third-party applications to hold the CAPTURE_AUDIO_OUTPUT permission by default, only privileged applications, such as those distributed by Google or the device vendor, can access audio output. However, adversaries may be able to gain this access after successfully elevating their privileges. With the CAPTURE_AUDIO_OUTPUT permission, adversaries may pass the MediaRecorder.AudioSource.VOICE_CALL constant to MediaRecorder.setAudioOutput, allowing capture of both voice call uplink and downlink. On iOS devices, applications must include the NSMicrophoneUsageDescription key in their Info.plist file to access the microphone.
Read it on attack.mitre.orgWhat MITRE says you would watch
- AN1772
A defender observes an application holding microphone capture capability transitioning into active microphone resource usage through Android audio APIs (e.g., MediaRecorder or AudioRecord), followed by sustained capture while the application is backgrounded or the device is locked, and subsequent outbound network traffic suggesting potential audio exfiltration or streaming.
- AN1773
A defender observes an application with declared microphone capability initiating microphone resource use through iOS audio frameworks, potentially during background execution or shortly after a silent wake event, followed by sustained audio capture and outbound encrypted traffic suggesting audio streaming or upload activity.
Technique names and descriptions © MITRE ATT&CK®, CC BY 4.0. Not endorsed by MITRE.