Path: utzoo!attcan!uunet!wuarchive!cs.utexas.edu!usc!rutgers!netnews.upenn.edu!vax1.cc.lehigh.edu!cert.sei.cmu.edu!krvw From: CHESS@YKTVMV.BITNET (David.M.Chess) Newsgroups: comp.virus Subject: re: Is it possible ? (PC) Message-ID: <0001.9007121452.AA11310@ubu.cert.sei.cmu.edu> Date: 11 Jul 90 13:39:46 GMT Sender: Virus Discussion List Lines: 18 Approved: krvw@sei.cmu.edu > Is it possible to make something for PCs, which works effectively against > all the virus, old or new? Well, you can turn the machine off, and leave it off! *8) More seriously, Fred Cohen showed awhile back, in his thesis, that no 100% perfect virus detector is possible (all detectors will either miss some viruses, or accuse some non-viral programs of being viruses). On the practical side, it seems unlikely that any anti-virus can be even close to 100% effective against unknown viruses, since that would require being able to tell an intended change from an unintended change (and if we could do that, we could find all *bugs*, not just all viruses...). It's relatively easy, in general, to be 100% effective against any given *known* virus. DC