CISO Guidance

1) Is this information credible?

• Yes, the information is credible. Multiple security vendors, including Cisco Talos, Varonis, and Proofpoint, have reported on this threat, and Microsoft has acknowledged the issue.

2) How could this be relevant to my org’s assets, vendors, or processes?

• If your organization uses Microsoft 365 Exchange Online and relies on Direct Send for legacy systems, this threat is directly relevant.
• Vendors using Direct Send to communicate with your organization could also be vectors for attack.

3) What’s the actual technical risk?

• Direct Send allows unauthenticated emails to bypass traditional security checks, making it a vector for phishing and business email compromise attacks.
• Exploitation can lead to data breaches and unauthorized access to sensitive information.

4) What do we need to do to defend/detect/respond?

• Conduct an inventory of systems using Direct Send and assess the necessity of this feature.
• Enable the RejectDirectSend control once dependencies are mapped.
• Transition to authenticated SMTP where possible and establish secure SMTP relays for legacy systems.
• Enhance monitoring for anomalous email traffic and configure alerts for unauthenticated internal messages.

5) What’s the potential business/regulatory exposure?

• Potential exposure includes data breaches and non-compliance with regulations such as GDPR or HIPAA if sensitive data is compromised.
• Financial loss and reputational damage from successful phishing or BEC attacks.

6) Does it reveal a bigger trend?

• This situation highlights the broader trend of attackers exploiting legitimate features for malicious purposes, emphasizing the need for continuous security assessments.

7) What actions or communications are needed now?

• Communicate with IT and security teams to prioritize assessment and mitigation of Direct Send vulnerabilities.
• Inform stakeholders about potential impacts and planned security measures.
• Update security policies to reflect changes in email handling and authentication practices.