With one click, any semi-skilled hacker could have silently taken over a Fortnite account, according to a cybersecurity firm who says the bug is now fixed.
Researchers at Check Point say the three vulnerabilities chained together could have affected any of its 200 million players. The flaws, if exploited, would have stolen the account access token set on the gamer’s device once they’ve entered their password.
Once stolen, that token could be used to impersonate the gamer and log in as if they were the account holder, without needing their password.
The researchers say that the flaw lies in how Epic Games, the maker of Fortnite, handles login requests. Researchers said they could send any user a crafted link that appears to come from Epic Games’ own domain and steal an access token needed to break into an account.
“It’s important to remember that the URL is coming from an Epic Games domain, so it’s transparent to the user and any security filter will not suspect anything,” said Oded Vanunu, Check Point’s head of products vulnerability research, in an email to TechCrunch.
Here’s how it works: the user clicks on a link, which points to an epicgames.com subdomain, which the hacker embeds a link to malicious code on their own server by exploiting a cross-site weakness in the subdomain. Once the malicious script loads, unbeknownst to the Fortnite player, it steals their account token and sends it back to the hacker.
“If the victim user is not logged into the game, he or she would have to login first,” said Vanunu. “Once that person is logged in, the account can be stolen.”
Epic Games has since fixed the vulnerability.
“We were made aware of the vulnerabilities and they were soon addressed,” said Nick Chester, a spokesperson for Epic Games. “We thank Check Point for bringing this to our attention.”
“As always, we encourage players to protect their accounts by not re-using passwords and using strong passwords, and not sharing account information with others,” he said.
When asked, Epic Games would not say if user data or accounts were compromised as a result of this vulnerability.