T4 Printer-friendly version T4 is a virus with three known strains. The T4-A and T4-B strains were first discovered in June 1992 in a public domain application called GoMoku. T4-C was discovered in February of 1993 at the University of Illinois at Champaign-Urbana.

T4 infects applications and the Finder. T4 attempts to modify your System file startup (or boot) code. Modification of this code could interfere with loading system extensions at startup.

The T4-C strain infects applications and System files on an infected startup volume. When activated under System 6, T4-C immediately attempts to alter the resident System file, resulting in damage that causes INIT problems at load time (startup). Modifications of this code could even cause the infected Macintosh computer to crash during startup.