This section uses the E phrygian dominant scale (E,F,G#,A,B,C,D) and a Bb triad (Bb,D,F) as a basis for the solo. The E phrygian dominant riffs are played against an E5 chord and the Bb triad riffs are played against the Bb5/E power chord. The tune then repeats the first section.
For more information refer to the book Heavy Rock Guitar Styles.