Cernoch.1066
Description Cernoch.1066
It is not a dangerous memory resident parasitic virus. It hooks INT 12h, 21h, 4Ah and writes itself to the end of .COM files that are opened. On ChangeDir DOS calls it searches for .COM files and also infects them. INT 12h is used for virus "Are you here?" call. On any INT 4Ah call the virus decrypts and displays the message, it then halts the computer:
Wish happy birthday to Cernoch
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GW.1201
Description GW.1201
It is a harmless memory resident encrypted parasitic virus. It hooks INT 21h and writes itself to the end of COM and EXE files that are executed or closed. The virus checks file names and does not infect anti-virus programs and files with the names: AIDSTEST, DRWEB, COMMAND, IBM*, AVP.
While infecting the virus uses undocumented System File Tables. The virus also uses other tricks to hide itself in the memory and access system resources: it traces INT 13h to get original INT 13h handler and patches DOS kernel to intercept file accessing calls.
The virus is encrypted in files as well as in the system memory. When needed the virus decrypts routines, executes them and then encrypts.
The virus does not manifest itself in any way. At the beginning of its code it contains a set of instructions that looks like text string:
_GW
Gwar
Description Gwar
It is a very dangerous memory resident encrypted and stealth boot virus. It hooks INT 13h and writes itself to the boot sector of diskettes and MBR sector of hard drive that are accessed. The virus copies its TSR copy to the interrupt table. From January 1st till 7th the virus displays a message and erases sectors on the hard drive, the message looks like follows:
Gwar virus by T-2000
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