ABBA is a memory resident parasitic virus. It "hooks" itself to INT 21h and writes itself to the end of .COM and .EXE files that are executed.
Abba contains the following internal text strings:
COMMAND.COM
Program too big to fit in memory
:ABBA+ƒ*.*
E:ABBA+ƒ
The virus creates "ABBA+ƒnn" files with HIDDEN and READONLY attributes on the current drive, where "nn" is the number of files to be infected on this drive (with each infection the virus renames the infected file with an increased "nn" number). Depending on this number the virus manifests itself with a video effect if there is a Hercules video card installed.
