Hello everybody,
I've been having this issue since December now...
If you have HTTPS Inspection turned on, and visit an HTTPS website via IE10 with the UTM in Transparent Mode, your browser will crash. It might not happen immediately (but I have found that seems to be the case most of the time) but it will eventually happen.
I tried to set it to Decrypt and Scan only certain categories of websites, but it appears that it somehow still impacts websites not in those categories. I tried setting it to URL filtering only, and it still crashes. As long as one of the three radio options on the "HTTPS" tab of the Filter Profile is selected, this will happen.
From what I've heard from Sophos, this is a known issue (although it isn't listed on https://www.sophos.com/en-us/support/knowledgebase/117759.aspx) and the only "fix" is to use IE 11. It doesn't appear to affect non-IE browsers as far as I can tell.
To quote the Sophos engineer who helped me pin this one down, "I have talked to our L3 engineer and this is in fact a known issue. Unfortunately the problem arose from an update in IE and was later fixed by Microsoft in IE11 but IE10 has not been fixed. Our development team is looking into a fix but it might be some time.
The current suggestion is to update IE to IE 11 or not to use Internet Explorer for HTTPS filtering."
Of course, moving to IE 11 would be a perfectly fine, if it weren't for our LOB applications not being compatible with it yet. Also, we can't control what our guests browsers are going to be, and we would still like to keep filtering turned on for them.
This has been ongoing since at least December 18 of last year when I first reported it to Sophos.
Oddly enough, I'm not seeing any mention of this problem on these boards, so either everyone is on IE11 or this is highly environment-specific (I haven't been given any more details other than the quote above).
Anyone else running into this, or maybe has more insight into what the cause is specifically? Something to do with OCSP or CRL checking maybe?
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