From bleepingcomputer.com
Some ancient filetypes are making a comeback due to unwanted attention from cybercriminals looking for more effective ways to hide malware distributed through spam campaigns.
Specifically, two archives that today are mostly seen on computers of nostalgic geeks or professionals working with old files, have been used recently in spam campaigns to deliver info-stealing malware or a backdoor.
The popular file extensions for hiding malware include types that support embedding code or commands in a form or another, like the Microsoft Office documents with macros.
Researchers at Trend Micro spotted email malicious activity involving ARJ (Archived by Robert Jung) and Z data compression formats, which back in the days used to be worthy candidates for the archive types preferred by the users.