Discovery of the USA company's cover-up of the incident resulted in the firing of two employees responsible for its response to the hack, said Dara Khosrowshahi, who replaced co-founder Travis Kalanick as CEO in August.
Dowling says mistakes and breaches are bound to happen in the technology field, and if they do the company should be honest about it.
The company also hired Mandiant, a cybersecurity firm owned by FireEye Inc, to investigate the breach.
The Uber CEO said that he only recently learned that outsiders had broken into a cloud-based server used by the company for data and downloaded a "significant" amount of information.
Uber says it paid hackers $100,000 after they stole data past year on 57 million of its users. "We are changing the way we do business".
- Equifax loses credit - A breach by major American credit agency Equifax in September is seen as potentially more damaging than that of Yahoo because of the sensitivity of the data leaked.
"We are working closely with other agencies including the [National Crime Agency] NCA and [Information Commissioner's Office] ICO to investigate how this breach has affected people in the United Kingdom and advise on appropriate mitigation measures", the spokesperson said, but added that the NCSC has seen no evidence that financial details have been compromised.
Two members of the Uber information security team who "led the response" that included not alerting users that their data was breached were let go from the San Francisco-based company effective Tuesday, according to Khosrowshahi.
"We are very concerned about it and we're certainly going to inquire further", said James Boffetti, the senior assistant attorney general in charge of the bureau.
The concerns are not only limited to the breach itself; the strongest ire is coming from regulators over how Uber handled the cyberattack.
Two employees responsible for the hack were fired by the company. Fifty-seven million people is a significant chunk of Uber's user base, which hit 40 million monthly active riders past year.
New York Attorney General Eric Schneiderman on Tuesday launched an investigation into the incident.
Businesses need to recognise that data breaches are a threat they face and they should be prepared to deal with them effectively to maintain customer trust, say security advisers.
Sullivan and one of his deputies were ousted from the company as a result of the CEO's internal investigation, we're told. In addition to its legal troubles, Uber has faced criticism for sexual harassment issues, underpaying and deceiving drivers, questioning a rape victim, and surge pricing during times of crisis.