URL Filtering from Internet Traffic to Internal Websites

ryan_carroll — Mon, 08 May 2017 19:02:51 GMT

Been doing some searching but havn't come up with anybody doing this and if it has other problems / security ramifications I'm not aware of.

My problem:

We have an employee that is no longer working at our business but there personal computer at home is configured to our internal mail server. I can see the spam of authentication attempts from the user that no longer is here, which is caussing false alarms in security software. (Exchange activesync doing this)

Solution:

Block the IP address that these are coming from and let our help desk know if they get a call. However planning for future what happens if someone else gets that IP from the internet company and tries to visit our mail OWA website, they will get blocked without any good information.

Solution to the Solution:

Serve up a URL response page for that IP with URL filtering for the internal website.

I havn't tested this yet to see if it will work, I'm also unsure what security risks I'm taking on by serving up response pages to the internet. Of course I have no interest in serving up response pages to the nasty scanner IPs or other malicious traffic I find.

Re: URL Filtering from Internet Traffic to Internal Websites

Raido_Rattameister — Mon, 08 May 2017 23:12:57 GMT

Well if you statically block ip then you have to manually go and change it when IP of this "attacker" changes.

You can configure Vulnerability profile action to be block IP if Palo identifies brute force.

Not perfect solution but unless you can talk to the person and ask to reconfigure his/her email client not much you can do as attack victim.

In vulnerability profile IP can be blocked for max 1 hour so you still get quite some events but much less than currently.

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URL Filtering from Internet Traffic to Internal Websites

Re: URL Filtering from Internet Traffic to Internal Websites