The hacker group that calls itself Anonymous claimed Monday that it had infiltrated the servers of Booz Allen Hamilton and obtained tens of thousands of e-mail addresses and other sensitive data for military personnel.

In a new post on PirateBay, a site that hackers use to distribute vast caches of data, the group dubbed the leak “Military Meltdown Monday.” It claimed that it was surprisingly easy to hack into Booz’s systems and secure “90,000 military emails and password hashes.”

The data appeared to include e-mail addresses, as well as encrypted versions of passwords.

In “this line of work you’d expect them to sail the seven proxseas with a state-of-the-art battleship, right?” the Anonymous post said in describing the firm’s network defenses. “Well, you may be surprised as were when we found their vessel being a puny wooden barge.” 

Asked for comment, a spokesman for Booz directed The Washington Post to a tweet by the company: “As part of @BoozAllen security policy, we generally do not comment on specific threats or actions taken against our system.”

Because the passwords were encrypted, one of the greatest dangers of the leak may be that the e-mail addresses could be used to contact military personnel under false pretenses and lure them into revealing their unencrypted passwords.

Booz, headquartered in Tysons Corner, is a major contractor for the Pentagon and Department of Homeland Security.

Anonymous and its spin-off group, LulzSec, have claimed responsibility for a string of attacks against private firms and government agencies. Earlier this month, Anonymous claimed to have hacked the systems of a West Virginia-based IT security company and acquired data from the Army, the Navy, the Department of Justice and NASA.