Skull Virus

Virus Name: Skull Aliases: Necro V Status: Rare Discovered: January, 1993 Symptoms: .COM file growth; .EXE file corruption; graphic display Origin: United States Eff Length: 666 Bytes Type Code: PNCK - Parasitic Non-Resident .COM Infector Detection Method: AVTK, Sweep, ViruScan, F-Prot, NAVDX, VAlert, IBMAV, NAV, PCScan, ChAV, Sweep/N, NShld, Innoc, NProt, AVTK/N, IBMAV/N, NAV/N, LProt Removal Instructions: Delete infected files General Comments: The Skull, or Necro, virus was submitted in January, 1993, and is from the State of Pennsylvania in the United States. Skull is a non-resident, direct action infector of .COM programs, including COMMAND.COM. It will also "drop" a second virus, the Skull EXE virus, described below under variant(s). Since the Skull EXE virus also replicates, it is listed as a variant rather than as part of the base Skull virus. When a program infected with the Skull virus is executed, the Skull virus will infect one .COM file located in the current directory. If it cannot find a .COM program to infect, it will instead "drop" the Skull EXE virus indicated below by overwriting the beginning of an .EXE file. Programs infected with the Skull virus will have a file length increase of 666 bytes with the virus being located at the end of the file. The program's date and time in the DOS disk directory listing will not be altered. The following text strings are visible within the Skull viral code in infected .COM files: "*.COM" "PATH=" "*.EXE" The Skull virus doesn't do anything besides replicate and drop the Skull EXE virus indicated below. The Skull EXE virus displays a message when it is executed. Known variant(s) of Skull are: Skull EXE: Skull EXE is the overwriting virus which is dropped by the Skull virus indicated above. When a program infected by the Skull EXE virus is executed, the Skull EXE virus will infect one .EXE file located in the current directory, overwriting the first 466 bytes of the host file. Infected programs will not increase in size. The Skull EXE virus will then display a graphic "skull" on the system display, with the following message: "You cant execute this file: Its already dead!" This message is encrypted within the viral code. The following text string is unencrypted within the Skull EXE virus: "*.EXE" Origin: Pennsylvania, USA January, 1993.