Virus Name: Voronezh-Chemist
Aliases: Chemist, Video Mode, Voronezh-650
V Status: Rare
Discovered: January, 1992
Symptoms: .COM file growth; decrease in total system & available free
Eff Length: 650 Bytes
Type Code: PRhCK - Parasitic Resident .COM & .EXE Infector
Detection Method: Sweep, ViruScan, F-Prot, AVTK, IBMAV,
NAV, NAVDX, VAlert, PCScan, ChAV,
NShld, LProt, Sweep/N, Innoc, NProt, AVTK/N,
Removal Instructions: Delete infected files
The Voronezh-Chemist, or Chemist, virus was submitted in January,
1992. Its origin is unknown, though it is related to the Voronezh
and Voronezh-370 viruses. Voronezh-Chemist is a memory resident
infector of .COM programs, including COMMAND.COM.
The first time a program infected with the Voronezh-Chemist virus
is executed, this virus will install itself memory resident at the
top of system memory but below the 640K DOS boundary. Total system
and available free memory will have decreased by 2,048 bytes.
Interrupt 12's return will not have been moved. Interrupts 21 and
24 will be hooked by the virus.
Once Voronezh-Chemist is memory resident, it will infect .COM
programs when they are executed. Infected programs will have a
file length increase of 650 bytes with the virus being located at
the beginning of the infected file. The file's date and time in
the DOS disk directory listing will not have been altered.
The following text strings can be found within the viral code in
all Voronezh-Chemist infected programs:
"Video mode 80x25 not supported"
It is unknown if Voronezh-Chemist does anything besides replicate.
Known variant(s) of Voronezh-Chemist are:
Voronezh-650: Functionally similar to the Voronezh-Chemist
virus described above, this variant has three bytes which
Origin: USSR December, 1992.
See: Voronezh Voronezh-370