Microsoft 365 AitM Phishing Campaign Targets Payroll and Finance Emails
A widespread phishing campaign uses adversary-in-the-middle techniques to compromise Microsoft 365 accounts and target payroll and finance emails.
Why it matters
Compromise of payroll and finance-related emails can disrupt corporate financial workflows and expose sensitive monetary information.
SOC impact
Focus on monitoring authentication logs for unusual sign-in activity, especially from residential proxies that may indicate masked malicious access. Investigate email accounts related to payroll and finance for suspicious forwarding or unusual access patterns. Correlate alerts with known phishing attempts leveraging adversary-in-the-middle methods targeting Microsoft 365 tenants.
Recommended actions
- Identify payroll and finance-related Microsoft 365 accounts and review their login activity.
- Monitor for sign-ins originating from residential IP addresses and proxy services.
- Inspect email forwarding rules and mailbox permissions for unauthorized changes.
- Analyze phishing email patterns linked to Microsoft 365 adversary-in-the-middle attacks.
- Correlate telemetry with alerts from email security gateways and MFA systems.
Executive Summary
A recent extensive phishing campaign targets Microsoft 365 users by employing adversary-in-the-middle techniques designed to hijack accounts, primarily those handling payroll and finance communications. Attackers obscure malicious sign-ins by using residential proxies, blending their activity with typical consumer traffic. This approach elevates the risk of undetected infiltration into financial email threads, potentially compromising sensitive corporate workflows. Operationally, it is critical to concentrate on identifying anomalous authentication events and scrutinizing changes in mailbox behavior within affected groups.
SOC Impact
Focus on monitoring authentication logs for unusual sign-in activity, especially from residential proxies that may indicate masked malicious access. Investigate email accounts related to payroll and finance for suspicious forwarding or unusual access patterns. Correlate alerts with known phishing attempts leveraging adversary-in-the-middle methods targeting Microsoft 365 tenants.
Authentication and Email Activity Validation
- Identify payroll and finance-related Microsoft 365 accounts and review their login activity.
- Monitor for sign-ins originating from residential IP addresses and proxy services.
- Inspect email forwarding rules and mailbox permissions for unauthorized changes.
- Analyze phishing email patterns linked to Microsoft 365 adversary-in-the-middle attacks.
- Correlate telemetry with alerts from email security gateways and MFA systems.
Why It Matters
Compromise of payroll and finance-related emails can disrupt corporate financial workflows and expose sensitive monetary information.