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 . 3sg.7z
According to an article from Ars Technica , the 7-Zip utility contained a flaw that allowed attackers to bypass Windows' security feature. Key Details of the Vulnerability Opening it reveals an inner archive (sometimes disguised
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. According to an article from Ars Technica ,
This inner file triggers an automatic download of a final malware payload, bypassing MotW restrictions entirely.
This vulnerability was patched in 7-Zip version 25.00 . Users are strongly advised to update to the latest version via the official 7-zip.org site to ensure they are protected. Safety Warning
Be cautious of sites like 7zip.com (note the .com extension), as Malwarebytes has reported that these fake download sites distribute trojanized versions of the software that can turn your PC into a proxy node for cybercriminals. Have you to the latest version recently?