What was the name of the massive data breach at the US Office of Personnel Management in 2015?

The massive data breach at the US Office of Personnel Management (OPM) in 2015 was one of the largest data breaches in US government history. The breach was discovered in April 2015 and affected over 21 million people. The data that was stolen included sensitive information such as names, dates of birth, social security numbers, and fingerprints.

The breach was attributed to a Chinese cyber-espionage group and is believed to have been carried out in two separate attacks in 2014 and 2015. The attackers gained access to the OPM's network through a third-party contractor that had been granted access to OPM's systems.

The breach led to widespread criticism of the OPM's security practices and raised concerns about the government's ability to protect sensitive data. In response to the breach, the OPM launched a number of initiatives to improve its cybersecurity, including increasing the number of staff dedicated to cybersecurity and implementing two-factor authentication for employees accessing sensitive data.

The breach was known as the OPM data breach, or the OPM hack.