misrepresentation at the consulate

[euro26]

My friend was supposed to visit my wife in the US but his visa was refused because he forgot that he was once denied entry into the US. When asked by the officer if he was ever denied entry, he said that he was not and the officer told him that he cannot issue him a visa because of misrepresentation of facts.
What kind of a waiver should he get? Is it I-601?

Thank you!