Why FortiSandbox Inline Scanning Fails to Block Malicious Files
A network administrator notices that FortiGate is not blocking a known malicious file that was submitted to FortiSandbox and received a 'malicious' verdict. The firewall policy includes a FortiSandbox inline scan profile. What is the MOST likely cause?
Quick Answer
The answer is that the FortiSandbox is not configured as an inline scanner in the antivirus profile. Inline scanning requires the FortiSandbox to be explicitly set as the scanner within the antivirus profile applied to the firewall policy; without this configuration, FortiGate will submit files for analysis but will not block them during transit, even if a malicious verdict is returned. On the Fortinet NSE 7 Advanced Security NSE7 exam, this question tests your understanding of the difference between inline and scheduled scanning modes—a common trap is assuming that simply enabling a FortiSandbox inline scan profile in the firewall policy is sufficient. The key distinction is that the antivirus profile itself must designate the FortiSandbox as the inline scanner; otherwise, files pass through unblocked while analysis runs asynchronously. Memory tip: think “profile within a profile”—the antivirus profile must call the FortiSandbox as its scanner for real-time blocking to engage.
⚠ Common exam trap
Test-takers frequently confuse the firewall policy's 'FortiSandbox inline scan profile' with the antivirus profile's inline scan setting, assuming that referencing a sandbox profile in the policy is sufficient to enable file submission, when in fact the antivirus profile must also have the inline scan option explicitly enabled.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The FortiSandbox is not configured as an inline scanner in the antivirus profile
The FortiGate uses an antivirus profile to define how files are scanned, including whether to send files to FortiSandbox for inline analysis. Even if the firewall policy references a FortiSandbox inline scan profile, the antivirus profile must have the 'FortiSandbox inline scan' option enabled to actually forward files to the FortiSandbox appliance. Without this setting, the FortiGate will not submit files for sandboxing, so a malicious verdict from FortiSandbox is never applied to the traffic.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The antivirus signature database is outdated
Why it's wrong here
Outdated signatures would affect signature-based detection, but FortiSandbox uses behavioral analysis independent of signature dates.
- ✗
The FortiSandbox license has expired
Why it's wrong here
An expired license would prevent new submissions but would not affect previously cached verdicts.
- ✓
The FortiSandbox is not configured as an inline scanner in the antivirus profile
Why this is correct
Inline scanning requires configuration in the antivirus profile to forward files to FortiSandbox for real-time analysis and enforce blocking based on verdict.
- ✗
The file is larger than the maximum file size allowed for scanning
Why it's wrong here
Large files may be skipped, but the scenario indicates the file was submitted; size limits would have prevented submission.
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Same concept, more angles
3 more ways this is tested on NSE7
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. An administrator configures a FortiGate to integrate with FortiSandbox for inline scanning. The policy has an antivirus profile with FortiSandbox enabled. What condition must be met for files to be submitted to FortiSandbox?
medium- ✓ A.The antivirus profile must use proxy-based inspection mode
- B.The FortiSandbox must be on the same subnet as the FortiGate
- C.The FortiGate must be in NAT mode
- D.SSL inspection must be disabled
Why A: For files to be submitted to FortiSandbox during inline scanning, the antivirus profile must use proxy-based inspection mode. This is because proxy-based inspection allows the FortiGate to buffer the entire file, perform deep analysis, and then forward it to FortiSandbox for verdict-based blocking. Flow-based inspection, in contrast, streams packets and cannot hold files for submission, making proxy mode a prerequisite for inline FortiSandbox integration.
Variation 2. An administrator configures FortiSandbox inline scanning for HTTP traffic. They notice that files uploaded via HTTP are being scanned but no verdict is being returned, causing delays. What is the MOST likely cause?
medium- A.The FortiSandbox has reached its maximum storage capacity
- B.The FortiSandbox is not registered with the FortiGate
- ✓ C.The file scan timeout is too short, causing FortiGate to pass the file before a verdict is received
- D.The file type is not supported by FortiSandbox
Why C: When FortiGate sends a file to FortiSandbox for inline scanning, it waits for a verdict before allowing the traffic to proceed. If the file scan timeout is too short, FortiGate will stop waiting for the verdict and pass the file anyway, causing the observed delay without a final verdict. This is the most likely cause because the administrator sees scanning occurring but no verdict returned, which aligns with a premature timeout rather than a failure to scan.
Variation 3. When configuring FortiGate with FortiSandbox integration, an administrator wants to block files that are rated 'High Risk' by the sandbox. Which setting must be enabled in the antivirus profile to automatically quarantine these files?
hard- A.Configure an automation stitch to quarantine files based on sandbox verdict
- B.Enable 'File Filter' in the antivirus profile and add a rule for high-risk files
- ✓ C.Enable 'Submit Files to FortiSandbox' and set action to 'Block'
- D.Enable 'FortiSandbox Quarantine' in the IPS profile
Why C: The 'Submit Files to FortiSandbox' setting in the antivirus profile, when set to 'Block', directly instructs FortiGate to quarantine files that receive a 'High Risk' verdict from FortiSandbox. This action is part of the antivirus profile's sandbox integration, not a separate automation or IPS feature, and it automatically handles the quarantine without requiring additional configuration.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This NSE7 practice question is part of Courseiva's free Fortinet certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the NSE7 exam.