Eight months after disclosing a major data breach, ride service Uber is focusing its legal efforts on learning more about an Internet address that it has persuaded a court could lead to identifying the hacker. That address, two sources familiar with the matter say, can be traced to the chief of technology at its main U.S. rival, Lyft.

In February, Uber revealed that as many as 50,000 of its drivers' names and license numbers had been improperly downloaded, and the company filed a lawsuit in San Francisco federal court in an attempt to unmask the perpetrator.