Massive Attack

The provided news articles do not contain any information about the organization or group known as "Massive Attack." Therefore, it is impossible to provide a summary about them based solely on these articles. The articles focus on two separate topics: a protest in London supporting Palestine Action, resulting in over 500 arrests, and an investigation by Reuters into the identity of the street artist Banksy. The Palestine Action protest involved a silent sit-in at Trafalgar Square, demanding the lifting of a ban on the organization. The Banksy article discusses the ongoing mystery surrounding the artist's identity and the efforts to uncover it. Neither article provides any context or information related to Massive Attack.