Elaborate hoax or the real deal? An anonymous post on a popular security disclosure site during the weekend claiming to have accessed T-Mobile's databases, financial documents, and other sensitive data has the wireless provider currently investigating whether the data and systems are truly in the hands of bad guys.

A post on the Full Disclosure list asks for "serious offers" to purchase the supposedly stolen database access and documents from T-Mobile, and that the booty will go to the highest bidder. "We have everything, their databases, confidential documents, scripts and programs from their servers, financial documents up to 2009," the post reads.

The purported perpetrators also include a long list of servers and a database table they say belongs to T-Mobile. But security experts say much of the information could have been gathered via a penetration test, and doesn't necessarily confirm they have the goods.

"I would have thought they would have provided a few snippets of actual recovered data," says Paul Henry, security and forensic analyst for Lumension Security. "The data they showed publicly is nothing more than that which could be produced with a well done pen test."

T-Mobile said in a statement Monday that if there's any evidence that customer data was breached, it would alert the victims ASAP. "The protection of our customers' information, and the safety and security of our systems, is absolutely paramount at T-Mobile. Regarding the recent claim, we are fully investigating the matter. As is our standard practice, if there is any evidence that customer information has been compromised, we would inform those affected as soon as possible," the statement said.

And in an updated statement issued today, T-Mobile confirmed that the list was legitimate: the firm said it has "identified the document from which information was copied, and believe possession of this alone is not enough to cause harm to our customers."

Security experts said yesterday it may be that the attackers are hyping a smaller breach of some less-valuable information, experts say, but based on their post, there's no way to tell at this point. "I think they really got into some system and have some documents, but it's unlikely that they've got any worthy information," says Robert Graham, CEO of Errata Security.

Just what "financial documents" they may have, for instance, is key to knowing just how sensitive and valuable the data they may have stolen really is.

The alleged attackers also say they attempted to sell the data to T-Mobile's competitors, but didn't get any takers. "We already contacted with their competitors and they didn't show interest in buying their data -- probably because the mails got to the wrong people -- so now we are offering them for the highest bidder," they said in the Full Disclosure post.

David Maynor, CTO at Errata Security, says the situation doesn't appear to be a prank because the attackers are soliciting buyers. "If it were a prank, they would not want anyone to know it was a prank" in order to keep the scam going as long as possible, he says.

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