A virus is said to be “in the wild” if it is spreading uncontained among infected computers in the general public. It must be spreading on and between the computers of unsuspecting users as a result of normal day-to-day operations. A virus being studied in a controlled environment for research purposes would not be considered “in the wild.” Also, a virus (or Trojan) that exists but is not actively spreading is also not considered to be “in the wild.” The first known computer virus to appear outside the computer or lab where it was created (i.e. “in the wild”) was the Elk Cloner virus written in 1981 for the Apple DOS 3.3 operating system, which spread via floppy disks. It was created as a practical joke. The first PC virus was called (c)Brain and was created by the Farooq Alvi Brothers in Pakistan in 1986 as a software piracy deterrent.
Viruses in the wild tend to be destructive enough to wipe out entire hard drives and even the computer’s BIOS, which is the microprocessor’s start-up program. Macro viruses that are written to affect Microsoft Office applications such as Word and Excel can account for up to 75% of all viruses found in the wild. Cross-site scripting viruses that inject malicious code into websites in order to infect the site’s visitor’s computer have also been found in the wild and, according to Symantec in 2007, accounted for 80% of all security vulnerabilities.