Virus Name: Cholera
Aliases: Cholera.1497, Cholera.1497.A
V Status: New
Discovery: July, 1995
Symptoms: .COM & .EXE growth; decrease in available free memory
Eff Length: 1,497 - 2,064 Bytes
Type Code: PRhAK - Parasitic Resident .COM & .EXE Infector
Detection Method: F-Prot, AVTK, VAlert, Sweep, IBMAV, NAV,
NAVDX, ViruScan, ChAV,
Sweep/N, AVTK/N, IBMAV/N, NAV/N, NProt, NShld,
Removal Instructions: Delete infected files
The Cholera, Cholera.1497 or Cholera.1497.A, virus was received
in July, 1995. Its origin or point of isolation is unknown.
Cholera is a memory resident infector of .COM and .EXE files,
When the first Cholera infected program is executed, this virus
will install itself memory resident at the top of system memory
but below the 640K DOS boundary, not moving interrupt 12's return.
Available free memory, as indicated by the DOS CHKDSK program from
DOS 5.0, will have decreased by 2,048 bytes. Interrupts 08 and 21
will be hooked by the virus in memory.
Once the Cholera virus is memory resident, it will infect .COM and
.EXE files, including COMMAND.COM, when they are executed. Infected
.COM files will have a file length increase of 1,497 bytes while
.EXE files will increase in size bye 2,052 to 2,064 bytes. In both
cases, the virus will be 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 string is visible within the viral
code in all infected programs:
"Cholera v1.0 by dr Hellraiser 94-02-03"
It is unknown what the Cholera virus may do besides replicating.
Known variant(s) of Cholera are:
Cholera.1497.B: Also received in July, 1995, this is a minor
variant of the Cholera virus described above. It contains the
following text string:
"Cholera v2.0 by dr Fleischman 93-12-29"
System hangs may occur when infected programs are executed.
Origin: Unknown July, 1995.