Chicago (IL) - A hacker claims to have gotten hold of a mountain of sensitive data from software company Valve, including credit card information from users who have purchased content from its digital distribution system Steam.

An online user by the pseudonym MaddoxX has posted a message on an anti-Valve site with pictures of what he claims are internal Valve files, including the company's balance sheet and customer transaction data.

When concerned users began talking about the reported hack on Valve's official message boards, the conversations were deleted. Valve has not yet made an official statement about the events, which began to unfold yesterday afternoon.

MaddoxX's online profile says he is a 22-year-old man from Russia. In his original posting, MaddoxX writes, "Woohoo VALVe you can see those creditcards...on the internet anytime soon. [I] just need to finish the excel files." Moreover, he seems to be holding the sensitive data hostage and asking for some kind of ransom. Calling out Valve, he says, "I prefer you come with something good unless you want me to expose ALL of the customers [and] their information."

If the hack is serious, Valve is legally obligated to inform its customers in some states.

Valve has not yet responded to our inquiries.