Source: Splunk Author: unknown URL: https://www.splunk.com/en_us/blog/security/hunting-m365-invaders-navigating-the-shadows-of-midnight-blizzard.html

ONE SENTENCE SUMMARY:

The blog discusses Microsoft’s cybersecurity incident involving Midnight Blizzard and develops detection strategies for similar attacks on M365 tenants.

MAIN POINTS:

1. Microsoft disclosed a cybersecurity incident attributed to the state-sponsored actor, Midnight Blizzard.
2. The Splunk Threat Research Team analyzed the incident and shared detection strategies for defenders.
3. Midnight Blizzard used password spray attacks on a non-MFA legacy tenant account.
4. Detection engineers can identify traditional password spray attacks using specific error codes.
5. The threat actor compromised an OAuth application with elevated access to corporate resources.
6. Monitoring for application permission updates helps detect privilege escalation attacks in Entra ID.
7. New OAuth applications can present monitoring challenges due to frequent legitimate triggers.
8. Midnight Blizzard manipulated service principal privileges to bypass standard consent operations.
9. Email details from compromised accounts can be tracked using the ‘Mailitemsaccessed’ event.
10. Organizations must adapt detection strategies to address novel cloud attack vectors and misconfigurations.

TAKEAWAYS:

1. Be aware of potential threats from state-sponsored actors like Midnight Blizzard.
2. Implement multifactor authentication (MFA) to secure tenant accounts against password spray attacks.
3. Regularly monitor and audit OAuth applications and their associated permissions.
4. Develop tailored detection analytics for unusual application activity in Entra ID.
5. Strengthen understanding of cloud security threats and evolve detection strategies accordingly.