Virus Name: LockUp
Aliases: LK, Mithrandir III
V Status: Rare
Discovered: May, 1992
Symptoms: Hidden .COM files created; decrease in total system &
available free memory; "Divide Overflow" errors may occur
Eff Length: 496 Bytes
Type Code: SRhE - Spawning Resident .EXE Infector
Detection Method: ViruScan, AVTK, F-Prot, Sweep, ChAV,
IBMAV, NAV, NAVDX, VAlert, PCScan,
NShld, Sweep/N, LProt, Innoc, AVTK/N, NAV/N, IBMAV/N
Removal Instructions: Delete the hidden .COM files
The LockUp virus was isolated in Sweden in May, 1992. This virus
is a memory resident spawning or companion virus which infects
.EXE programs, and uses some stealth techniques to avoid detection.
The first time a program infected with the LockUp virus is executed,
the virus will will install itself memory resident at the top of
system memory but below the 640K DOS boundary. It does not move
interrupt 12's return. Total system and available free memory, as
indicated by the DOS CHKDSK program, will have decreased by 1,568
bytes. Interrupt 21 will be hooked by LockUp in memory.
Once the LockUp virus is memory resident, it will infect .EXE
programs when they are opened or executed. Infected .EXE programs
are not altered, but rather the virus creates a hidden 496 bytes
.COM file in the directory with the same base file name. These
hidden files always have the file date and time of 3-24-23 2:17a
in the DOS disk directory. After the virus has created the hidden
file, any time the user attempts to execute the infected .EXE program,
the companion .COM program will be executed by DOS.
The following text strings can be found in the 496 byte companion
.COM files created by the LockUp virus:
When the LockUp virus is memory resident, it attempts to mask the
presence of the hidden .COM files in order to avoid detection by
anti-viral programs. The programs may not see the hidden files, so
no virus will be found.
Known variant(s) of LockUp are:
LockUp-B: Functionally equivalent to the original virus, this
variant has three bytes which differ.
Origin: Sweden October, 1992.