Virus Database

ACG.a

Description ACG.a

It is a family of DOS parasitic viruses. There are several virus versions known: memory resident and nonmemory resident, infecting COM and/or EXE files. All of them write themselves to the end of the file and modify file header. Memory resident viruses hook INT 21h and infect files that are opened, nonmemory resident search for files in the current directory.
The viruses use highly complex polymorphic engine that rebuild virus code. In different infected files different assembler instructions or ever sets of instructions are used to do the same operation. The engine also mixes blocks of virus code and data, inserts junk instructions, inserts random data, etc. The virus also changes data offsets in its assembler instructions, constants and so on. As a result, the virus is not 100% encrypted, but it has no constant parts of code and ever the length of virus is changed.
Being installed into the memory the memory resident versions of the virus do not changes the virus code anymore, and all its replications have constant set of instructions. After reboot the virus installs itself into the memory and generates new set of instruction and infects files with this new set.
The viruses contain the text:
Internal compiler error!
LUCKY B.R.D 1994-99

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GranGrave.1150

Description GranGrave.1150

It is not a dangerous memory resident parasitic virus. It hooks INT 21h and writes itself to the end of EXE files that are accessed. When DOS functions GetDiskSpace or DeleteFCB (AH=13h,36h) are called, the virus search for EXE files of the current directory, and infects them. The virus checks the name of the file, and does not infect the file if its name contains "V" or "S" symbols, or begins with: "CL", "HW", "TB", "F-", "WC", or "TK".
Depending on the system timer the virus displays the message:
Burglar/H

The virus also contains the text strings:
AT THE GRAVE OF GRANDMAall
CLHWTBF-WCTK
*.*

Grapje.1039

Description Grapje.1039

It's a non memory resident very dangerous virus. It hits the .COM-files at their beginning. The files can be infected incorrectly. These files are not recoverable and hang-up computer while running. This virus types: "GRAPJE!!" and contains the text strings: "*.COM", "*.*".

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