Here is a compilation of some of the top 5 single hacking attacks in recent years

1. Operation Shady RAT
Last year security firm McAfee revealed details of Operation Shady RAT (RAT is an acronym for Remote Access Tool), a hacking campaign that took place over several years. The networks of 72 organisations across the world were targeted in the campaign which began in mid-2006, or perhaps earlier, and continued until at least 2010. Targets included the United States government, the UN, 12 US defence contractors and several technology firms.
McAfee said it believed that a “state actor” was behind the attacks and that it was impossible to say how much data was stolen. Though McAfee declined to say which country was behind the attacks, most experts believe China to be the most likely perpetrator.

2. TJX
The precise details of large-scale financial hacks are often kept private but there are several attacks that are contenders for the title of ‘most expensive hack’. One is the 2007 attack on American firm TJX, which was mounted from an insecure WiFi network in one of the company’s TJ Maxx shops. More than 45 million people had their credit card details stolen and some experts said the actual figure was likely to be closer to 94 million.

3. Heartland Payment Systems
This New Jersey payment processing firm lost data on tens of millions of credit cards in an attack in 2009. Around 175,000 businesses were affected by the theft, which was led by hacker Alberto Gonzalez, who was also implicated in the TJX attack.

4. Epsilon
The world’s largest email marketing firm, Epsilon, confirmed in 2011 that it had been the target of hackers. Only names and email addresses were stolen from the firm, which handles more than 40 billion emails every year more than 2,000 brands worldwide including Marks and Spencer. The scale of the theft was unprecedented.

5. Sony PlayStation Network
In 2011, hackers gained access to Sony’s PlayStation Network, putting at risk credit card data for more than 70 million people. The gaming service was closed for weeks and customers were eventually compensated with free games and subscriptions. Though the culprits were never caught, it is now believed that no data was stolen and the attack was intended to simply embarrass Sony.