Message Hygiene & ProtectionAnti-Malware & Safe Attachments

Anti-Malware & Safe Attachments

25 mins

Understanding the Concept

Anti-malware policies in Exchange Online scan all email attachments for known malware signatures. The service uses multiple anti-malware engines for high detection rates and can block specific file types by extension.

Safe Attachments (Defender for Office 365) provides advanced protection by detonating suspicious attachments in a sandbox environment. This catches zero-day threats that signature-based scanning might miss.

Common attachment types like executable files (.exe, .bat, .cmd) can be automatically blocked. The ZAP (Zero-hour Auto Purge) feature removes malicious messages that were already delivered if a threat is detected after delivery.

Key Points

•Multi-engine malware scanning for all attachments

•Common attachment type filtering blocks dangerous file extensions

•Safe Attachments detonates files in sandbox (Defender P1/P2)

•ZAP removes delivered malicious messages retroactively

•Admin quarantine notifications alert about malware detections

•Dynamic Delivery sends message body while scanning attachment

Why This Matters

Email-borne malware is a primary vector for ransomware and data breaches. Multi-layered attachment scanning combined with sandbox detonation provides defense-in-depth against both known and zero-day threats.

Common Mistakes to Avoid

✗Not enabling ZAP to catch post-delivery threats

✗Blocking too many file types causing business disruption

✗Confusing Safe Attachments with standard anti-malware scanning

Interview Discussion Points

💡Explain the difference between signature-based and sandbox-based malware detection

💡Describe how ZAP works and when it activates

💡Discuss how to handle a malware outbreak via email

MS-203 Exam Tips

📝Know which anti-malware features are in EOP vs Defender for O365

📝Understand Safe Attachments policy modes: Monitor, Block, Replace, Dynamic Delivery

📝Be familiar with ZAP behavior for spam, phishing, and malware

Anti-Spam & Anti-Phishing Policies

Quarantine Management