Detection Strategy for Spearphishing Voice across OS platforms

Technique Detected:  Spearphishing Voice | T1566.004

ID: DET0245
Domains: Enterprise
Analytics: AN0683, AN0684, AN0685, AN0686
Version: 1.0
Created: 21 October 2025
Last Modified: 21 October 2025

Analytics

AN0683

Monitor call log records from corporate devices for unusual or unauthorized numbers, especially repeated calls to/from known malicious phone numbers. Correlate with subsequent system events (e.g., browser navigation, remote management tool execution).

Log Sources
Data Component Name Channel
Application Log Content (DC0038) ApplicationLog:CallRecords Outbound or inbound calls to high-risk or blocklisted numbers
Mutable Elements
Field Description
PhoneNumberBlocklist List of known malicious or suspicious phone numbers; must be tuned per environment
TimeWindow Threshold for correlating call events with subsequent suspicious system activity

AN0684

Audit VoIP/SIP logs for suspicious outbound calls or call setup messages to unusual endpoints. Correlate with user activity such as browser execution or package installation following the call.

Log Sources
Data Component Name Channel
Application Log Content (DC0038) networkdevice:syslog SIP REGISTER, INVITE, or unusual call destination metadata
Mutable Elements
Field Description
CallDestinationPatterns Regular expressions or rules for spotting abnormal call destinations
UserContext Expected users who initiate VoIP traffic vs. anomalous accounts

AN0685

Monitor Facetime, iMessage, or SIP client logs for anomalous voice call attempts. Link to subsequent user execution events (downloads, RMM installs) triggered post-call.

Log Sources
Data Component Name Channel
Application Log Content (DC0038) macos:unifiedlog Outgoing or incoming calls with non-standard caller IDs or unusual metadata
Mutable Elements
Field Description
CallerIDPatterns Patterns of spoofed caller IDs that must be tuned based on region and telecom provider
PayloadCorrelation Define what follow-on events (browser downloads, execution) to correlate with call logs

AN0686

Correlate MFA push fatigue or unusual consent grant attempts with call activity where adversaries may have socially engineered the user over voice.

Log Sources
Data Component Name Channel
Application Log Content (DC0038) m365:unified Unusual MFA requests or OAuth consent events temporally aligned with user-reported vishing call
Mutable Elements
Field Description
MFARequestThreshold Number of MFA push requests within a timeframe aligned to a suspicious call
ConsentGrantPatterns Unusual OAuth consent URLs or delegated scopes