Attackers used a nested archive technique (an archive inside another archive). While the outer file (like 3sg.7z ) would be flagged by Windows as downloaded from the internet, the inner archive would not inherit this "Mark of the Web" tag.
Opening it reveals an inner archive (sometimes disguised with Cyrillic characters to look like a document).
This allowed malicious files inside the inner archive to be executed without triggering standard Windows security warnings, such as SmartScreen. Attack Sequence: User downloads a malicious file like 3sg.7z .
