Fly 1.1 Virus
Virus Name: Fly 1.1
V Status: Rare
Discovered: April, 1993
Symptoms: .COM & .EXE growth; write protect errors on diskettes;
decrease in total system & available free memory
Eff Length: 1,771 - 1,786 Bytes
Type Code: PRhAK - Parasitic Resident .COM & .EXE Infector
Detection Method: F-Prot, Sweep, NAV, IBMAV, AVTK, ViruScan,
NAVDX, VAlert, PCScan, ChAV,
NShld, Sweep/N, NAV/N, AVTK/N, IBMAV/N, Innoc
Removal Instructions: Delete infected files
The Fly 1.1 virus was submitted in April, 1993. Its origin or
point of isolation is unknown. Fly 1.1 is a memory resident infector
of .COM and .EXE programs, including COMMAND.COM.
When the first Fly 1.1 infected program is executed, the Fly 1.1
virus will install itself memory resident at the top of system
memory but below the 640K DOS boundary, not moving interrupt 12's
return. Total system and available free memory, as indicated by the
DOS CHKDSK program, will have decreased by 3,200 bytes. Interrupt
21 will be hooked by Fly 1.1 in memory.
Once the Fly 1.1 virus is memory resident, it will infect .COM and
.EXE programs, including COMMAND.COM, when they are executed.
Infected programs will have a file length increase of 1,771 to
1,786 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 encrypted within the
Fly 1.1 viral code:
Systems infected with the Fly 1.1 virus will experience write
protect errors when the user attempts to execute programs from
write protected diskettes when the virus is memory resident.