Data compromised in the United Airlines hack includes manifests, which detail the passengers, origins and destinations of individual flights, Bloomberg says. This information could be added to China's growing database on US defense and intelligence officials, and it could be cross-referenced with previously stolen medical and financial records, according to those familiar with the breach.

This hack is not directly linked to reported network glitches in June and July that that caused United to ground all flights, the site reports. However, Bloomberg says it appears that the hackers were lurking in United's network for months, and one domain linked to the attack was set up in April 2014.