“The only security features you can apply using SSL certificate inspection mode are web filtering and application control... Note that while offering some level of security, certificate inspection does not allow FortiGate to inspect the flow of encrypted data.”

“To perform SSL inspection on traffic flowing through the FortiGate device, you must allow the traffic with a firewall policy and apply an SSL inspection profile to the policy... For antivirus or IPS control, you should use a deep-inspection profile.”

“When you use deep inspection, FortiGate impersonates the recipient of the originating SSL session, and then decrypts and inspects the content to find threats and block them. It then re-encrypts the content and sends it to the real recipient.”

Technical Deep Dive:

The exhibit shows that the policy is allowing HTTPS and the SSL/SSH inspection profile is certificate-inspection , not deep-inspection . That is the key issue. With certificate inspection, FortiGate can inspect only SSL metadata such as the certificate and SNI/hostname context; it cannot decrypt the HTTPS payload itself. Because EICAR is detected by antivirus through payload inspection, FortiGate must see the file contents. Without deep SSL inspection, the antivirus engine never gets the decrypted payload, so the file can pass even though the antivirus profile is attached.

Option A is incorrect because FortiGate firewall policies often use ACCEPT + security profile enforcement ; the session can still be blocked by antivirus after policy match. Option B is incorrect because web filter is not required for antivirus detection. Option C is incorrect because the real requirement is deep SSL inspection , not specifically proxy-based mode; full SSL inspection is the deciding factor here.

In practice, to block EICAR over HTTPS, you would apply a deep-inspection SSL profile to the policy, for example:

config firewall policy

edit < policy-id >

set inspection-mode flow

set av-profile " default "

set ssl-ssh-profile " deep-inspection "

next

end

On real hardware, this also matters for performance design. Simple firewall/NAT sessions are often NP fast-pathed, but once you enable deep SSL inspection and content scanning, traffic is typically handed to CPU/WAD/content-inspection path for decryption and scanning, so throughput is lower than certificate-inspection or no-inspection.