Semtex virus (1997) hook INT 8, 21h and write themselves to the end of .COM files that are opened or executed. Sometimes they fill the screen with random data. They contain the texts:
“Semtex.515,619,1000.a”:
S E M T E X by Dusan Toman, CZECHOSLOVAKIA (7)213-040 or (804)212-23
“Semtex.686”:
!!! explosive !!! S E M T E X !!! explosive !!! Written by Dusan Toman, CZECHOSLOVAKIA Pyrotechnician Lilo Hedera (7)213-040 or (804)212-23
“Semtex.1000.b”:
S E M T E X by Dusan Toman, CZECHOSLOVAKIA *** Have a nice day ***