From Video Game Music Preservation Foundation Wiki
String Attack! is one of the 9 different songs that are played during a regular game if using the MIDI audio track. It is the fourth track that is played. The tracks are played in sequence starting from Sick Sate Rittim and ending with Rain, at which point the list starts over from the beginning.
The track was composed by Stephen Rippy using a Boss DSS-330 synthesizer and an E-mu ESI-32 sampler. Finally, the mixing and editing was done using SoundForge. Even though the music piece was composed as full CD quality, the track was used only in the separate MIDI track in the final game. The MIDI version of the track was composed in Cakewalk.
The song title has been confirmed by Stephen Rippy.