Russian computer hackers placed a "digital bomb" capable of sabotaging data and derailing the US economy into Nasdaq's computer systems, it has emerged.
The cybercriminals slipped the "cybergrenade" into Nasdaq's computer network in 2010 using malware capable of spying and stealing data, according to Bloomberg Businessweek.
The bomb was never set off, but had the capability of derailing stock market computers. An FBI system monitoring of US internet traffic picked up the alert and found that the hackers had used "zero day" vulnerabilities.
Zero days are previously unknown flaws in computer code that allow hackers to easily take remote control of a computer.
A similar type of malware has been designed and built by Russia's main spy agency, the Federal Security Service of the Russian Federation. However, Russian officials denied any government connection to the security breach.
Investigators also discovered evidence that the Russian malware was being used by a sophisticated Chinese cyberspy known to be operating a thriving criminal business.
The US treasury department's Office of Critical Infrastructure Protection and Compliance Policy has drawn up a list of 10 major US stock exchanges and banks that might be targets of a broader campaign.
Nasdaq spokesman Joseph Christinat told Bloomberg Businessweek: "Our own forensics review of the issue conducted in close cooperation with the US government concluded no proof of exfiltration of data from our director's desk systems.
"Importantly, 2010 was a watershed moment in our company's commitment to cybersecurity resulting today in an enhanced ability to detect and protect the integrity of our systems, our technology, and market participants."
A previous breach of Nasdaq's computer systems was traced by the US Secret Service to a group of alleged Russian cybercriminals led by a St Petersburg-based man named Aleksandr Kalinin.