An unidentified hacker reportedly breached the Xbox 360 and PSP ISO forums, exposing the details of over 2.5 million gamers' accounts. According to independent security expert Troy Hunt, hackers targeted the "XBOX360 ISO" and "PSP ISO" forums back in September 2015, compromising the email addresses, account passwords and IP addresses, the Daily Mail reports.

The hackers behind the intrusions have not been identified yet. Users have been advised to change all of their accounts' passwords.

"Data breaches are often sold via darkweb sites or within closed trading circles," Hunt, who runs the breach notification website HaveIBeenPwned, told the publication. "The prevalence of password reuse means that a relatively benign site can hold credentials that unlock far more valuable resources, for example, email or social media accounts."

Gaming ISO files are exact copies of existing games that have been copied from the original disc. These ISO forums are used by gamers to swap links to free downloads of different games for each gaming system and illegally download the pirated copies.

As seen in previous massive breaches, hackers who swipe users' information and data usually dump it online after they have quietly exploited it.

"Once a site or impacted members knows there's been a breach, the data becomes less valuable as people change passwords and do other things to protect their identities," Hunt said. "It can take quite some time before attackers decide the usefulness of the data has been exhausted and they then offer it for sale publicly or dump it."

According to ESET IT security specialist Mark James, breaches like these are quite common where victims find out about them only months or even years after their data has been stolen.

"Scams and phishing attacks will try and use the valuable data to entice even more information from the unsuspecting user," James told IBTimes UK. "That info is tested, stored and often will be used for identity theft purposes.

"Quite often people using seemingly low security websites don't enforce good password security because it's not a financial target. But all data has value and will be reused for other purposes."

Alien Vault IT security advocate Javvad Malik says gaming forums have become a ripe and favoured target for hackers to exploit in recent months.

The official forums of Polish game studio CD Projekt Red, the developer behind The Witcher, were hacked in a breach that reportedly took place in March 2016 and compromised more than 1.8 million user accounts. Earlier in January, Clash of Clans developer Supercell confirmed that its community forum was breached in September 2016, affecting around 1.1 million accounts.

"Typically [gaming forums] have weaker security, so it is easier for attackers to gain access to the passwords," Malik said. "Attackers rely on the fact that most users will reuse the forum password on other sites."

"There is no such thing as a 'low priority' public site wherever a user account resides," Malik said, adding that the need for effective security monitoring controls that can help detect cyberthreats and attacks in a timely manner has never been more crucial.

"In this day and age, discovering a breach over a year after the attack is an eternity," he said.