One unusual "feature" of this virus is that it will search the disk for
the string "Microsoft" and change it into "MACROSOFT". The virus will not
infect programs if the environment contains SYSLOCK=@.
Two minor variants, which will transform the string "Microsoft" into
"MACHOSOFT". One is very close to the original SysLock virus, with only
one byte different, but the other has been modified somewhat.