As is the case with all software, where exactly you download Windows 11 from matters. If you venture outside the confines of Microsoft's Windows Insider program, you could end up with more than you bargained for, as there is an installer making the rounds which contains a malicious download manager.
According to Kaspersky, the malicious installer is labeled 86307_windows 11 build 21996.1 x64 + activator.exe. It checks in at 1.75GB, so at a glance, it might appear to some as a legitimate installation file. However, most of that space belongs to a single DLL file containing "a lot of useless information."
It does not actually Windows 11 at all. Instead, it asks for permission to fetch a second executable that it pitches as a download manager for Windows 11, complete with a license agreement to also install a bit of sponsored software. Users who accept the agreement end up with a variety of not-so-fun applications installed on their PC, with varying levels of maliciousness.
"Those other programs can be very wide-ranging—from relatively harmless adware, which our solutions classify as not-a-virus, to full-fledged Trojans, password stealers, exploits, and other nasty stuff," Kaspersky warns.
Having all that unleashed on your system could ruin your day in a hurry. It's not the only malicious Windows 11 installer out there, either.
While it may seem obvious to avoid downloading Windows 11 from third-party sources, a leaked build was the only way for curious folks to take a sneak peek at the upcoming OS before it was made available in the Windows Insider program.
Now that an offical source is here, however, that is the only place you should grab it. Joining the Windows Insider program is free and easy. Just be aware that preview builds are essentially unfinished versions that can contain bugs and may not be completely stable on some setups.
If you want to give Windows 11 a test run but aren't keen on installing it wholesale on your PC, using a virtual machine is relatively risk free. I can confirm it runs fine on VMWare's Workstation 16 Player (version 16.1.2), which is also a free download.