Virus writers began to take their work seriously. The computer underground had already mastered an array of new polymorphic generators and constructors, and founded new electronic publications. This year saw new viruses which employed new techniques to infect files, penetrate systems, destroy data and conceal themselves from antivirus applications.
One such example is the PMBS virus which worked in the secure regime of Intel 80386 processors. Another example was the Strange (or Hmm) virus, the only stealth virus, however, executed on the level of device interruption at INT 0Dh and INT76h.
Carbuncle signaled a new generation of companion viruses. A number of other viruses like Emmie, Bomber, Uruguay, and Cruncher employed fundamentally new techniques to conceal themselves in the code of infected files.
The spring of 1993 turned out to be a nerve-wracking time for many antivirus vendors: Microsoft released its own antivirus program. Microsoft AntiVirus (MSAV) was based on the former Central Point AntiVirus (CPAV). The program was included in the standard delivery of MS-DOS and Windows operating systems. The first tests conducted by independent testing laboratories showed a high level of effectiveness. However, later on, its quality began to slowly decline and the project was discontinued.