Skip to Main Content
All Trimarc services are now delivered through TrustedSec! Learn more

Business Email Compromise in Microsoft 365

Take swift action to contain and recover from email attacks.

Email drives modern business communication, but the rising threat of business email compromise (BEC) by cybercriminals jeopardizes data security and integrity.

In today's digital age, collaborative environments have become the lifeblood of business communication, and Microsoft 365 (M365) is at the forefront of this transformation. However, this digital transformation comes with a growing threat - BEC. Cybercriminals and threat actors are constantly looking for ways to compromise sensitive information, commit fraud, and steal valuable data.

TrustedSec’s BEC offering provides a low-cost way for companies to quickly determine what actions attackers took within their M365 environment after they were compromised. Analysis will include examining M365 user activities for:

  • Attacker Sign-Ins
  • Evidence of files accessed or downloaded
  • Emails sent by attackers
  • Unauthorized MFA devices
  • Malicious mailbox rules

Additionally, TrustedSec searches the M365 tenant for other users that may have been compromised so the organization can be assured if their compromise has been contained.

BECs require swift action by organizations to contain and recover from an attack. TrustedSec’s BEC analysis lets every organization quickly respond to the attack, determine what actions were taken by attackers, and be confident that the compromise is resolved.

Learn more about our services from an expert.

Let our experts tailor solutions to your security challenges.

Read our blog

Explore the latest cybersecurity topics on the TrustedSec Security Blog

Blog March 24 2026

Building a Detection Foundation: Part 4 - Sysmon

Filling the Gaps Native Logging Can'tAt this point in our series, we have Windows Security events capturing logon sessions and process creation, and…

Read about this article
Blog March 10 2026

Building a Detection Foundation: Part 3 - PowerShell and Script Logging

The Second Most Important Data Source You're Probably Not CapturingIn Part 2, we enabled process creation logging with command lines. That's a big…

Read about this article
Blog March 05 2026

Building a Detection Foundation: Part 2 - Windows Security Events

The Audit Policies Nobody ConfiguresIn Part 1, we looked at why relying on a single telemetry source is a recipe for blind spots. Now let's get practical.…

Read about this article
Blog February 24 2026

Building a Detection Foundation: Part 1 - The Single-Source Problem

The Uncomfortable Truth About Your Telemetry Let me start with an observation that might hit close to home. In my years working Incident Response cases and…

Read about this article
Blog January 22 2026

Adventures in Primary Group Behavior, Reporting, and Exploitation

If you’ve administered Active Directory (AD) for any significant time, chances are you’ve come across the primaryGroupID attribute. Originally developed as a…

Read about this article
Blog January 08 2026

Updating the Sysmon Community Guide: Lessons Learned from the Front Lines

Over the past few weeks I’ve been spending a significant amount of time updating the Sysmon Community Guide. This wasn’t driven by theory, trends, or what…

Read about this article
Blog July 17 2025

Hiding in the Shadows: Covert Tunnels via QEMU Virtualization

Attackers are getting increasingly creative—not just with their payloads, but with how they deliver and operate them. In a recent Incident Response engagement,…

Read about this article
Blog August 29 2024

Gobbling Up Forensic Analysis Data Using Velociraptor

Lately I have been working with Velociraptor for its endpoint and digital forensic capabilities and specifically spent time in many cases in the past two years…

Read about this article
Blog April 04 2024

Observations From Business Email Compromise (BEC) Attacks

Since joining TrustedSec, I have gotten to work numerous cases, and each of them is like unraveling a mystery to get at the truth—especially the situations…

Read about this article
Blog March 21 2024

Securing Sensitive Data: How Ransomware Challenges the Healthcare Industry

The healthcare industry is a prime target for ransomware attacks due to the critical nature of its services and the sensitive data it handles. This blog post…

Read about this article