Hackers who infiltrated Nasdaq's computer systems managed to do so by using malicious software on the PCs of directors of several publicly held companies. Investigators think that the attack was more serious than previously thought, as Nasdaq OMX Group had said in February that there was no evidence the hackers accessed customer information.

In fact no one knows what the hackers might have got their paws on and the investigation into the attack, involving the FBI and National Security Agency, is ongoing. Reuters reported that the long term impact of such attack is still unknown,

It was was an example of a "blended attack” where one attack allowed another. Nasdaq insisted that its trading platforms were not compromised by the hackers, but they attacked a Web-based software program called Directors Desk, used by corporate boards to share documents and communicate with executives, among other things. Hackers spied on "scores" of directors who logged onto directorsdesk.com before the malicious software was removed.