Stories from the SOC – Office 365 account compromise and credential abuse


Stories from the SOC is a blog series that describes recent real-world security incident investigations conducted and reported by the AT&T SOC analyst team for AT&T Managed Threat Detection and Response customers.

Executive Summary

Credential abuse and compromised user accounts are serious concerns for any organization. Credential abuse is often used to access other critical assets within an organization, subsidiaries, or another partner corporation. Once an account is compromised, it can be used for data exfiltration, or to further promote the agenda of a threat actor. Threat actors often compromise the internal email accounts of legitimate organizations for many reasons including to send internal users phishing links leading to additional compromise, to send malicious emails to external users for later compromise, or create inbox rules to forward confidential emails to the threat actor’s account outside of the organization. Monitoring for events surrounding internal, inbound, and outbound email activity is important.

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