No Frills is a resident file infector which infects both COM and
EXE files.
When an infected file is executed, the virus will install itself in
memory and reserve 1kB for itself. At this time virus hooks INT 21h.
INT 21h handler defines the residence test and intercepts dos functions
4Bh (load program), 3Dh (open file handle), 43h (get/set attribute) and
6Ch (extended open/create). All EXE files that start with 'MZ' or 'ZM'
and whose names don't begin with "SC" are candidates for infection.
All COM files which do not have "CO" at the beginning of the filename
are also candidates. Virus contains a copyright text inside its code
which says '+-No Frills 2.0 by Harry McBungus-+'. Virus size is
843 bytes.
