The ex-executive was repeatedly questioned at the Old Bailey, London, about News International's (NI) claim between 2007-9 it was limited to one "rogue reporter" after royal editor Clive Goodman and private investigator Glenn Mulcaire admitted accessing voicemails.
She was also asked about her involvement in offering Goodman a job when he got out of jail and in paying off PR guru Max Clifford in a £1 million deal, moves that effectively headed off the threat more staff would be implicated in hacking.
Mrs Brooks, 45, a former NI chief executive, was being cross-examined by prosecutor Andrew Edis, QC, on her ninth day in the witness box. She denies conspiring to hack phones and other charges.
During the investigation into Goodman and Mulcaire, Mrs Brooks had been told Mulcaire had accessed voicemails of 100-110 people.
Mr Edis asked: "You believed NI's behaviour between 2007-9 was honourable, did you?" Mrs Brooks replied: "At the time I did."
Mr Edis: "So you carried on with it when you became chief executive?"
Mrs Brooks: "What?"
Mr Edis: "The cover-up."
Mrs Brooks: "No."
The trial continues.