CSS-Exchange VS Cyber-Defence

The MaxServicePointIdleTime property I changed because of what I saw suggested here: https://github.com/microsoft/CSS-Exchange/issues/1581.

This is actively exploited, patch immediately. Microsoft also provided a script that checks Exchange items for malicious messaging items: https://github.com/microsoft/CSS-Exchange/blob/a4c096e8b6e6eddeba2f42910f165681ed64adf7/docs/Security/CVE-2023-23397.md

Microsoft has released a PowerShell script that can be run on Exchange infrastructure to scan email files for malicious UNC paths, however, patching is the preferred mitigation strategy.

I would expect that installing the URL Rewrite 2 module shouldn't cause any problems -- E2013 as such doesn't care about it. In fact, Microsoft's own EOMT script for the Hafnium mitigations suggests installing it. It'll likely require a reboot, though, or at the very least an IIS restart.

Yep, the August security update and OS updates were installed on all four nodes. But the order in which they were installed may have been different... I don't recall. Someone just posted above that this is a known problem with Windows 2012/R2: https://github.com/microsoft/CSS-Exchange/pull/1166

Which is the latest I can find on Github. This server is running Exchange 2019 CU 11. It has the March updates (KB5012698), but not the May one (KB5014261). You can also verify from the build number it's not up to date. There are no vulnerabilities reported and the only thing in "red" is that TCP keepalive warning.

https://github.com/microsoft/CSS-Exchange/issues/535 Even the maintainer David Paulson of the ExchangeHealtcheck script opened an issue on this matter, only waiting on feedback of the Exchange Team.

Unfortunately a few comments here have honed in on one contrived example of why I think this strategy is broken. To give another contrived example: I personally had a logon to this portal, but it broke last year when they integrated logons with Azure and it took me like three months to get it fixed.

The fact a critical security update can't just be downloaded is bad. I don't care if someone in sales thinks every licensed user should probably be able to get it. Here NCC produced a list of "valid" files to help people scan for not legit files. Except they don't have Exchange 2019 CU 8 because they couldn't get it:

https://github.com/nccgroup/Cyber-Defence/tree/master/Intell...

Microsoft has a hard limit (5?) on the number of individual accounts you can grant access and in a big enough org it's still plausible they'll be scattered across the world and you'll find none of them available the exact hour you need this update.