Virus Name: Overdoze
V Status: New
Discovered: July, 1995
Symptoms: .COM file growth; file date/time seconds = "02";
some .COM/.EXE may appear smaller in DOS directory listing;
decrease in available memory
Eff Length: 470 Bytes
Type Code: PRhCK - Parasitic Resident .COM Infector
Detection Method: F-Prot, AVTK, VAlert, Sweep, NAV, NAVDX, IBMAV,
ViruScan, PCScan, ChAV,
NShld, NAV/N, Sweep/N, IBMAV/N, AVTK/N, NProt, Innoc 4.0+
Removal Instructions: Delete infected files
The Overdoze or Overdoze.470 virus was received in July, 1995,
along with one variant, Overdoze.472. Their origin or point of
isolation is unknown. Overdoze is a memory resident infector of
.COM files, including COMMAND.COM.
When the first Overdoze 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 496 bytes. Interrupt 21 will be
hooked by the virus in memory.
Once the Overdoze virus is memory resident, it will infect .COM
files, including COMMAND.COM, when they are executed. Infected
files will have a file length increase of 470 bytes, though this
file length increase will be hidden when the virus is resident
in memory. The virus will be located at the end of the file. The
file's date and time in the DOS disk directory listing will not
appear to be altered, though the seconds field will have been set
to "02", the infection marker for the virus. The following text
string is visible within the viral code in all infected files:
"[Overdoze] (c) 1994 The Unforgiven/Immortal Riot"
The Overdoze virus hides the file length increase on infected files
by decreasing the file length shown in a DOS directory listing by
470 bytes for any file whoms file date/time seconds = "02". As a
result, some uninfected files with a file date/time seconds field of
"02" will appear to be smaller than they actually are.
Known variant(s) of Overdoze are:
Overdoze.472: Also received in July, 1995, this is a 472 byte
variant. It is functionally similar to the Overdoze virus
described above and contains the same text string.
Origin: Unknown July, 1995.