What if someone were able to access your phone’s microphone without your permission? This scenario is not just an invasion of privacy, but it also poses a potential threat to your security. Android developers recently discovered a vulnerability in the AlwaysOnHotwordDetector.java, specifically in an element called AlwaysOnHotwordDetector, where a missing permission check could lead to a local escalation of privilege. The concerning part about this issue is that it doesn't require any additional execution privileges, nor does it need user interaction for exploitation.

Affecting Android 10 and Android 11, this security flaw carries the Android ID A-229793943. Though this issue is not pervasive, it’s important to understand the details of this vulnerability and how it can be exploited so that we can take the necessary steps to protect ourselves.

Understanding the Code Snippet: AlwaysOnHotwordDetector.java

For those interested in the technical aspect, let's take a look at a relevant code snippet from AlwaysOnHotwordDetector.java:

private void startRecognition(int recognitionFlag) {
    if (mRecognitionStatus != STATUS_LISTENING) {
        try {
            int audioSessionId = obtainAudioSession();
            if (audioSessionId > ) {
                mAudioConfig = new AudioConfig(audioSessionId, mSampleRate,...);
                        mKeyphraseMetadata, mAudioConfig, recognitionFlag);
                mRecognitionStatus = STATUS_LISTENING;
        } catch (RemoteException e) {
            Slog.e(TAG, "RemoteException in startRecognition!", e);

The missing permission check in question is in the startRecognition() function, which initiates the hotword recognition process. If an attacker can somehow gain access to this function and call it, the microphone will start listening in the background without checking for the necessary permissions.

Exploiting the Vulnerability

The real danger lies in the possibility of exploiting this vulnerability, which can be done without user intervention. Access to the microphone can potentially allow attackers to record conversations and background noise, all unbeknownst to the user.

For bad actors to exploit the vulnerability, they would need to access the specific code section of the affected AlwaysOnHotwordDetector.java. Following this, they must call the startRecognition() function remotely, activating the microphone in real-time or continuously recording audio without user's knowledge.

For further reading and understanding, please visit the following official source(s)

- CVE-2022-20446 on the Android Security Bulletin
- AlwaysOnHotwordDetector.java Source Code

Conclusion and Recommendations

While this vulnerability may not affect every Android user, it’s crucial to be aware of the implications and remain diligent about your smartphone’s security. Practice safe habits, such as installing updates promptly and only downloading apps from trusted, verified sources. You should also follow device manufacturers and Android security bulletins to get updates about any document and solution available for these vulnerabilities.

Remember that staying informed and taking action is the best way to protect your mobile device and personal information from potential threats. In the world of cybersecurity, knowledge truly is power!


Published on: 11/08/2022 22:15:00 UTC
Last modified on: 11/09/2022 15:52:00 UTC