Russian hackers were somehow able to plant a "digital bomb" into the systems of NASDAQ in 2010, which would have been able to severely damage the computers in the stock market and cause untold chaos on the economy of the United States.

The hackers, whose identities have not yet been identified even after four years, infiltrated the network of NASDAQ with customized malware which had the ability to do surveillance and extract data. However, the malware was also capable of causing widespread disruption in the NASDAQ computer system.

The hack attack was reported by Bloomberg Businessweek, which detailed the events leading up to the discovery of the planted digital bomb.

In October 2010, an FBI system that was monitoring the Internet traffic in the United States was alerted by a signal coming from NASDAQ, which looked like malware had infiltrated the company's servers. The signal showed that the attack was not just a harmless prank but rather the kind that has the characteristics of a foreign intelligence agency. When experts checked out the malware, they came to the conclusion that it was actually an attack code, which was created to cause significant damage.

The discovery of the digital bomb led to the launch of a five-month investigation that was led by the National Cybersecurity and Communications Integration Center. The investigation tested the capabilities of the United States to respond to such a cyber attack that was discovered.

While the digital bomb was successfully intercepted before it did any damage, its discovery reveals the vulnerability to digital attacks of stock exchanges, as well as other facilities such as banks, electric and water utilities, and chemical refineries, among others. 

The FBI, to this day, has not collected enough evidence to make the conclusion that the attacks were directed by a foreign government. However, Bloomberg is alleging that the Russian government was behind the attack, to which Russian Embassy spokesman Yevgeniy Khorishko vehemently denied.

"It is pure nonsense that it is not even worth commenting on," Khorishko said.

People familiar with the ongoing investigation, however, said that the attack was more likely done by Aleksandr Kalinin, an independent hacker from St. Petersburg who the FBI and U.S. Secret Service say has been caught attacking NASDAQ systems between 2007 and 2010.

NASDAQ reassured the traders and companies listed under them that the hackers from four years ago were not able to extract any information, and that the digital bomb was never detonated.

"The events of four years ago, while sensationalized by Businessweek, only confirmed what we have said historically: that none of Nasdaq's trading platforms or engines were ever compromised, and no evidence of exfiltration exists from directors' desks," said NASDAQ spokesman Ryan Wells.