FWIW, AIX comes with a virus-scanning utility (/usr/bin/virscan),
though IIRC the original version had an empty signature file (in
/usr/lib/security/scan/virsig.lst) and even the later populated
signature file only contains PC viruses.  Quoth the man page, "at
this time [virsig.lst] contains no known AIX virus signatures".
Apparently we are to infer that there *were* no known AIX virus
signatures.

I note that my 4.2.1 AIX system still has the 1991 signature file.

Even a DOS-only virus list could potentially be useful on a Unix
file server, though.  Provided, of course, that it had a recent
signature list (and preferably mutant-detection and similar
heuristics), which virscan probably does not.

And to be fair there are plenty of Unix vulnerabilities, and even
viruses potentially among them.  David Harley, keeper of the
alt.comp.virus FAQ, mentioned some "lab" Unix viruses when this
thread appeared in October '87, and I recall a discussion of using
crypto hashes to validate major system commands on some Unix group
not that long ago - which is essentially virus-scanning technology,
though not necessarily for the same purpose it generally serves
on PCs.

That said, viruses are not the problem for Unix systems that they
are for PCs.  Network security, guessable usernames and passwords,
and the like should generally be a higher priority.

Some parts © 2009 Advameg, Inc.