Zscaler was deployed on a Windows 11 machine at a place that a friend worked at. When I assessed the software, its behavior was downright evil like malware. As we all know, it injects its own root certificate into the operating system in order to conduct man-in-the-middle attacks on TLS/HTTPS connections to monitor the user's web activity.

Furthermore, it locks down the web browser's settings so that you cannot use a proxy server to bypass Zscaler's MITM. I saw this behavior in Mozilla Firefox, where the proxy option is set to "No proxy" and all other options are disabled and grayed out; I imagine that it does the same to Google Chrome. If you try to modify the browser's .ini(?) file for proxy settings, Zscaler immediately overwrites it against your will. Zscaler worked very hard to enforce its settings in order to spy on the computer user.

And as you'd expect, if you open up the Zscaler GUI in the system tray, you are presented with the option to disable the software if you have the IT password. Which of course, you don't have. Then again, that might be an epsilon better than the Cybereason antivirus software, which just has a system tray icon with no exit option, and cannot be killed in Task Manager even if you are a local administrator, and imposes a heavy slowdown if you're open hundreds of small text files per second.

I feel the same way about Cisco Umbrella where I work.

The worst breakage by far is protocol breakage; basically anything that uses HTTP as a basis for building some other protocol gets broken all the time. None of the people implementing it seem aware. They buy the vendor's claim that it's "transparent", when in fact even "inspect/trace-only" modes often break all kinds of shit.

I've seen Umbrella break:

  - Git
  - RubyGems
  - `go mod`
  - OrbStack
  - Matrix
  - Cargo
  - all JDKs
  - Nix
  - Pkgsrc
  - all VMs

and probably some other things I'm forgetting. When this breakage is reported, the first round of replies is typically "I visited that domain in my enterprise-managed browser and it's not blocked". That is, of course, a useless and irrelevant test.

Often it takes hours to even fully diagnose the breakage with enough confidence to point the finger at that tool and not some other endpoint security tool.

I'm not sure if the people buying and deploying tools in this category don't know how much stuff it breaks or just don't care. But the breakage is everywhere and nobody seems prepared for it.

SSH certificates aren't X.509 certificates.