Does an antivirus also scan for viruses targetting other OSes other than the one it runs on?

Today my company has some external support personnels coming over and 1 of them bought a thumb drive containing the files for the fix to the driver problems.

The IT manager of my company requested for the thumb drive and ran it through 1 of the Windows computer's antivirus, before clearing them to proceed.

However, as I noticed, they were doing things on Macs and not on a Windows machine. So I wonder if my IT manager has been doing something that isn't too useful afterall.

Do most consumers' antivirus softwares typically also scan for viruses that target other operating systems and not just scan for viruses harmful only to the OS it is installed on?

Solution 1:

I cannot say about all consumer antivirus products, but most of them scan for all threats on all platforms, since they have a unified database of virus/malware signatures, which is used by all products, regardless of the platform. For example:

Microsoft Security Essentials lists MacOS threats in their Malware Protection Center, and all these signatures are included in all their products, including Windows consumer products (Security Essentials).

Solution 2:

Yes they can, if programmed for that attitude. For example: ClamAV written for Linux (after wards ported for windows etc.) but it can scan viruses which written for windows.

Solution 3:

Yes. For example, there are solutions (e.g. AVG, ClamAV) which run on Linux servers, typically on file servers or e-mail servers. Their main purpose there is to prevent viruses (as well as SPAM) to get into the networks (e.g. via e-mails), to spread around (via internal file servers).