Microsoft Defender Alert Details
Alert ID: MD-AUDIO-CAPTURE-1123-7842 Alert Time: 2024-02-27 16:30:45 EST Severity: HIGH (88/100) Source: Microsoft Defender for Endpoint Rule: “Microphone Access by Suspicious Process” MITRE ATT&CK: T1123 – Audio Capture
Alert Details:
Detection: Process accessing microphone without user interaction
Host: CONF-ROOM-001 (Conference Room PC) User: SYSTEM (no user logged in) Time: 16:15-16:30 EST
Process Details:
Process: C:\Windows\Temp\audio_recorder.exe (PID: 4789)
SHA256: a1b2c3d4e5f67890a1b2c3d4e5f67890a1b2c3d4
Parent: services.exe (running as service)
User: SYSTEM
Audio API Calls:
waveInOpen (open microphone device)
waveInPrepareHeader (prepare buffers)
waveInAddBuffer (add buffers for recording)
waveInStart (start recording) – 3 times
waveInStop (stop recording)
waveInClose (close device)
Files Created:
C:\ProgramData\Microsoft\Audio\recording_20240227_1615.wav (2.3 MB)
C:\ProgramData\Microsoft\Audio\recording_20240227_1620.wav (2.4 MB)
C:\ProgramData\Microsoft\Audio\recording_20240227_1625.wav (2.3 MB)
Detection Logic:
Process accessing microphone with no user logged in
Audio recordings saved to hidden folder (ProgramData)
Process running as SYSTEM (elevated)
Pattern matches room monitoring/spying
SOC Investigation Process
Step
Action
Tools Used
Findings
1. Alert Validation
Verify Defender alert
Microsoft 365 Defender
Confirmed audio capture from conference room PC
2. Process Analysis
Analyze audio_recorder.exe
Defender Sandbox
Malware that records audio and saves locally
3. Immediate Action
Terminate process
Defender
Process killed
4. File Deletion
Delete executable and recordings
Defender
Files removed
5. Physical Security
Check conference room
Security Team
Room empty; no unauthorized access found
6. Network Investigation
Check for exfiltration
Firewall Logs
No audio files exfiltrated
Jira Incident Report
Ticket: SOC-2024-139 Summary: T1123 – Audio Capture Malware on Conference Room PC Status: RESOLVED Resolution: MALICIOUS – Audio Recording Stopped Priority: P2 – MEDIUM Labels: T1123, audio-capture, microphone, defender, espionage Components: Endpoint-Security, Physical-Security
INCIDENT ANALYSIS REPORT
1. Initial Context:
Detection Source: Microsoft Defender for Endpoint.
Alert: “Microphone Access by Suspicious Process”.
Host: CONF-ROOM-001 (Conference Room PC).
Process: C:\Windows\Temp\audio_recorder.exe.
Files: 3 audio recordings (7 MB total).
Time: 2024-02-27 16:30 EST.
Technique: MITRE ATT&CK T1123 – Audio Capture.
2. Technical Analysis:
Attack Chain:
14:00 – Unknown individual entered conference room (piggybacked)
14:15 – Individual inserted USB drive with malware
14:20 – Malware installed as Windows service
15:00 – First audio recording session (missed – no one in room)
16:15-16:30 – Three recording sessions
16:30 – Defender detects
Malware Analysis:
Name: audio_recorder.exe
SHA256: a1b2c3d4…
Capabilities:
Installs as Windows service for persistence
Records audio when motion detected (or on schedule)
Saves recordings to hidden folder
Attempts exfiltration via FTP (blocked)
Recordings:
16:15 – 2.3 MB (approximately 5 minutes)
16:20 – 2.4 MB (approximately 5 minutes)
16:25 – 2.3 MB (approximately 5 minutes)
Content: Conversations from a meeting that occurred 16:15-16:30
Participants: 4 people (HR team discussing layoffs)
Physical Access:
Attacker gained physical access to conference room
Installed malware via USB
No badge access recorded (piggybacking)
3. Investigation Findings:
Timeline:
14:00 – Attacker enters room
14:15-14:20 – Malware installed
16:15-16:30 – Meeting recorded
16:30 – Defender alert
16:32 – SOC investigates
16:33 – Process terminated
16:34 – Files deleted
Indicators of Compromise (IoCs):
Files:
– C:\Windows\Temp\audio_recorder.exe (SHA256: a1b2c3d4…)
– C:\ProgramData\Microsoft\Audio\recording_*.wav (3 files)
Service:
– “Windows Audio Recorder” (disabled)
Physical:
– Conference Room 101, 2nd floor
4. Containment Actions:
Immediate Actions:
Terminated audio_recorder.exe.
Deleted executable and all recordings.
Disabled malicious service.
Scanned for other malware (none).
Physical Security:
Reviewed badge access logs (found piggybacking incident).
Increased security presence.
Implemented mantraps at entrances.
Meeting Participants:
HR team notified of potential privacy breach.
No evidence of exfiltration.
5. Root Cause Analysis:
Primary Cause: Physical security breach allowing unauthorized access.
Contributing Factors:
Conference room PC left unlocked.
USB ports enabled (should be disabled).
No physical security at entrance.
6. Business Impact:
Operational Impact: Conference room PC offline for 1 hour.
Privacy Impact: 15 minutes of confidential HR meeting recorded.
Reputational Impact: Potential if recordings leaked (prevented).
7. Remediation & Prevention:
Completed Actions:
Malware removed.
Recordings deleted.
Physical security enhanced.
Technical Controls Enhanced:
Disabled USB ports on public PCs.
Implemented automatic logoff for conference room PCs.
Added mantraps to secure entrances.
Enhanced monitoring for microphone access.
8. Conclusion:
An attacker gained physical access to a conference room and installed audio recording malware that captured 15 minutes of a confidential HR meeting. Defender detected the microphone access and enabled rapid removal before any exfiltration.
Closure Rationale: Malware removed; recordings deleted; physical security enhanced.
Analyst: [Your Name], SOC Analyst Date: 2024-02-27 17:30 EST