WASHINGTON — Equifax, still reeling from a massive hack that exposed sensitive data about 143 million people, said Thursday that it will begin offering a new service next year that gives consumers more control over their data.

The service, to go live by Jan. 31, will allow consumers to ‘‘lock and unlock access to their Equifax credit files,’’ Paulino do Rego Barros Jr., the company’s interim chief executive, said in a Wall Street Journal editorial published late Wednesday. The service, to be offered free for life, will allow consumers to prevent anyone from accessing their credit file without their permission — making it harder for a hacker to obtain a credit card or take out a loan in their name, for example.

In the column, Barros acknowledged the company’s lackluster initial response to the hack, including an inadequate website.

‘‘We were hacked. That’s the simple fact,’’ he said. ‘‘But we compounded the problem with insufficient support for consumers. Our website did not function as it should have, and our call center couldn’t manage the volume of calls we received.’’ The company is working to correct its mistakes, Barros said. The company is also giving consumers concerned they may have been affected by the hack more time to sign up for TrustedID Premier, its free credit-monitoring service.

‘‘We have to see this breach as a turning point — not just for Equifax, but for everyone interested in protecting personal data,’’ he said. ‘‘Consumers need the power to control access to personal data.’’

Barros, appointed interim CEO Tuesday, appears to be acting quickly in the face of growing outrage over the hack. Equifax is already under investigation by the FBI, and the Consumer Financial Protection Bureau is calling for lawmakers to give it more power to oversee the industry. Next week, the company’s former CEO and chairman, Richard Smith, is scheduled to appear before two congressional committees. Democrats are calling on Congress to take potentially drastic action to reform credit-rating companies.