msg="User shutdown the device from forticron. The reason is 'System file integrity check failed'"

[raffaeledp]

Hello everybody, 

some days ago I received this error on my Fortigate F60 (v 7.2.10):

msg="User shutdown the device from forticron. The reason is 'System file integrity check failed'"

I searched for this error and I found the following guide: 

https://docs.fortinet.com/document/fortigate/7.2.5/administration-guide/249947

From this guide, I didn't understand very well. I'll try to explain:

what I understood is that this error appears beacause BIOS security level is 2 (I confirm) and, because the firmware (as well as the AV engine etc.) is signed by the Fortinet CA and a third-part CA, this integrity check fails.

Now, I have two question:

1) Who is this third-part CA?

2) If there is an integrity check error, how is it possible that the solution can simply be setting the security level to 1? How can we simply ignore this error?

I think I'm missing the point. Can someone explain to me this concept in a simple way?

Thank you so much!

[AlexC-FTNT]

Generally, these articles are better explained in the community portal.

For example: 

https://community.fortinet.com/t5/FortiGate/Technical-Tip-Understanding-the-log-message-User-shutdow...

1) Who is this third-part CA?

>> there are many certificate authorities online. It is the company that verifies and sells certificates that allows devices (usually seen as websites) to provide encrypted communication across internet.

2) If there is an integrity check error, how is it possible that the solution can simply be setting the security level to 1? How can we simply ignore this error?

>> here is what encryption level does:

https://docs.fortinet.com/document/fortigate/7.2.5/administration-guide/249947

In simple words: if you set this to 1, any attacker that obtains access to your fortigate can upload a certificate (not CA-trusted) and inspect your user traffic. FortiGate will trust that certificate without warning, so you don't know there was any attack or information leak (if exploited)