The 337 virus was received from Europe in May 1991. 337 is a memory resident infector of .COM programs. It does not infect COMMAND.COM.
The first time a program infected with 337 is executed, the virus will install itself memory resident as a low system memory TSR of 944 bytes. Interrupt 21 will be hooked by the virus.
Delete the infected files.
Once 337 is memory resident, it will infect .COM programs, other than COMMAND.COM, when they are opened or executed. Programs infected with 337 will increase in length by 337 bytes with the virus being located at the end of infected files. The program's date and time in the disk directory will not be altered.
337 does not do anything besides replicate.