Wallbleed, a buffer over-read vulnerability that existed in the DNS injection subsystem of the Great Firewall of China. Wallbleed caused certain nation-wide censorship middleboxes to reveal up to 125 bytes of their memory when censoring a crafted DNS query. It afforded a rare insight into one of the Great Firewall’s well-known network attacks, namely DNS injection, in terms of its internal architecture and the censor’s operational behaviors.
macOS and iOS don't support OpenVPN with the built-in client. You can use strongSwan-based VPNs (e.g., as would be deployed through Algo) or Cisco, but for OpenVPN you'll need a custom client which, unfortunately, very likely brings along its own .kext.
I think you may be confusing deterministic reproducible
builds (that remove randomness and ensure binaries
have the same content hash regardless of who builds
them (so you can reproduce what the maintainers did
and verify the source and binaries) to merely a repro'd
environment where everything still works because deps
are included, which seems to be all that Nix promises
(and in fact there is at least one open issue to add full
deterministic builds to Nix
https://github.com/NixOS/nixpkgs/issues/9731 )
Any comparatively large corporation very likely has a release process for these sorts of things where a bunch of groups (like PR, maybe Legal etc) would take a look. Releasing company IP as open source outside of such a process would be a gross violation of any number of non-disclosure agreements between employer and employee.
There's nothing in the OPs post suggesting SSH was exposed to the public, or that the breach happened over SSH. So it's important to secure that, but it's also important to think holistically about the attack surface.
You assume the breach happened over SSH. This is valuable information to securing SSH, but it's entirely possible the original breach happened over some other service, and there were some other steps involved in the breach before the SSH screenshot was taken.