Popular ride-hailing company Uber has hired Facebook's Chief Security Officer Joe Sullivan to head up its own security department.

The hiring has come at a time when Uber has been facing criticism for a number of security issues.

Uber revealed in February that a May 2014 hacking attempt may have leaked the data of 50,000 of its current and former drivers.

Last week, active Uber accounts were on sale on the black market for $1 apiece, including a user's username and password, as well as the last four digits of their credit card and its expiration date (Uber denies this data was taken off its servers, however).

The company has also come under fire for being lax about its user database and even posting publicly about user habits on its blog. Uber is also sued by San Francisco and Los Angeles district attorneys for not providing sufficiently robust background checks on its drivers.

It is notable that Uber's service has been blocked in a growing number of countries and metropolitan areas.

"With millions of riders being supported by an always-growing data infrastructure, we've invested significantly in expanding and improving safety and security," Uber CEO Travis Kalanick wrote in a blog post announcing the hire.

"It's no longer about traditional metrics for safe transportation or keeping our community?s data private and secure, but about how we lead efforts to redefine and strengthen physical and data security in the location-based world."

Sullivan has a good experience in digital privacy and security knowledge. After a role as a federal prosecutor specializing in high-tech crime, Sullivan worked as a senior director of eBay's Trust and Safety Department. In 2010, he took up the role of Chief Security Officer at Facebook after acting as general counsel for PayPal.