Facebook says it has found no evidence ‘so far’ that hackers broke into third-party apps after a data breach exposed 50 million users.
The social media giant said attackers exploited the site’s ‘View As’ feature, which lets people see what their profiles look like to other users.
Yesterday the firm revealed that hackers may have been able to break into any third-party service which a person used their Facebook logins to access – a feature called Facebook Single Sign-On.
Private data stored on thousands of websites that use the service, including Uber, Airbnb, Tinder, Spotify the New York Times and the Washington Post, could also have been accessed by cyber criminals.
However, the firm has now said it found no evidence ‘so far’ that the service was exploited.
It is now building a tool to enable developers to manually identify the users of their apps who may have been affected so that they can log them out.
‘This was a serious issue and we worked fast to protect the security of people’s accounts and investigate what happened’, Guy Rosen, VP of Product Management wrote in a blog post.
‘We have now analysed our logs for all third-party apps installed or logged in during the attack we discovered last week.
‘That investigation has so far found no evidence that the attackers accessed any apps using Facebook Login’, he said.
The vulnerability was fixed and users’ access tokens were reset.
Resetting the access tokens meant users had to log back in to Facebook or any of their apps that use Facebook Login.
Mr Rosen said that any developer using the official Facebook Software Development Kit (SDK) was automatically protected when people’s access tokens were re-set.
However, not all developers use Facebook SDKs.
Mr Rosen said that ‘out of an abundance of caution’ developers are ‘building a tool to enable developers to manually identify the users of their apps who may have been affected, so that they can log them out’.
Recent research revealed that some of the web’s most popular sites lack basic security precautions that would have limited the fallout of the Facebook hack.
They found that just two of the world’s 95 most popular sites – a list that includes Uber, Airbnb, the New York Times and the Washington Post – asked users to re-enter their Facebook password each time they used Facebook Single Sign-On.
The unknown attackers took advantage of a feature in the code called ‘Access Tokens,’ to take over people’s accounts, potentially giving hackers access to private messages, photos and posts – although Facebook said there was no evidence that had been done.
Mr Rosen laid bare the potential ripple effects in a conference call with reporters last week.
He said: ‘The access token enables someone to use the account as if they were the account holder themselves.
‘This does mean they could access other third-party apps using Facebook login.’
It is not clear whether hackers have used Facebook’s login service to access other apps, writes Business Insider.
However, it’s now more likely these firms will carry out investigations of their own.
Users that were logged out of the service between 27th and 28th September are likely to have been impacted by the breach.
As a result of the breach, the firm logged roughly 90 million people out of their accounts this week as a security measure.
Earlier this week a shocking report revealed Facebook logins were being sold on the dark web for just $3.90 (£3) each.
Email logins sell for as little as $2.70 (£2) each, according to experts who analysed the value of 26 commonly used accounts.
They found the majority of someone’s online life could be available for just $970, which includes all usernames, passwords and email addresses.
According to a blog post by Cheshire-based firm Money Guru, which carried out the research, these details are frequently stolen to sell to companies with want to do targeted advertising.
‘There are few better ways to gain insight into someone’s life than their social media accounts’, researchers wrote.
‘These details are frequently stolen to sell to companies with little scruples about targeted advertising.
‘It’s also a fast track to identity theft as they can take control of your accounts, lock you out and cause serious reputational damage in a short space of time’, they wrote.
As a result, some experts and officials have grown concerned about whether the firm can effectively manage and protect users’ data.
‘The implications of this are huge,’ Justin Fier, director of cyber intelligence at security company Darktrace, told Reuters.
The breach could also cause problems for Facebook with European privacy laws.
Facebook said it hasinformed the Irish Data Protection Commission about the breach, a step required by Europe’s GDPR regulations.
The commission said it received the notification, but expressed concern with its timing and lack of detail.
Virginia Sen. Mark Warner called the hack ‘deeply concerning’ and called for a full investigation.
‘…Today’s disclosure is a reminder about the dangers posed when a small number of companies like Facebook or the credit bureau Equifax are able to accumulate so much personal data about individual Americans without adequate security measures.
‘This is another sobering indicator that Congress needs to step up and take action to protect the privacy and security of social media users. As I’ve said before – the era of the Wild West in social media is over,’ he added.
Not long after the breach was announced, some Twitter users also began reporting that Facebook was blocking them from sharing links to stories about the hack from the Associated Press and The Guardian.
When users attempted to share the links, they were served a message that read: ‘Our security systems have detected that a lot of people are posting the same content, which could mean that it’s spam. Please try a different post.’
The move caused some to speculate that it was a result of Facebook suppressing negative coverage of itself. However, Facebook later confirmed to the New York Times that it was a result of an error with the firm’s spam detection tools.
Friday’s announcement sent Facebook’s stock plunging by as much as 3.4 percent in afternoon trading, adding to an already rough year for Facebook shares, which have fallen 6.7 percent so far this year.
Zuckerberg penned a post on his personal Facebook page about the incident, saying the issue was ‘patched last night’ but that the firm is working with law enforcement, including the FBI, to investigate the origins of the attack.
‘On Tuesday, we discovered that an attacker exploited a technical vulnerability to steal access tokens that would allow them to log into about 50 million people’s accounts on Facebook,’ Zuckerberg wrote.
Access tokens don’t include a user’s password, but they do allow users to log into a Facebook account without needing it.
‘Our security systems have detected that a lot of people are posting the same content, which could mean that it’s spam,’ the notice said. ‘Please try a different post.’
Zuckerberg acknowledged in a statement to reporters that Facebook needs to take additional steps to prevent these kinds of issues from occurring in the future.
‘We’re taking it really seriously…We have a major security effort at the company that hardens all of our surfaces,’ Zuckerberg said in a call with reporters.
‘I’m glad we found this. But it definitely is an issue that this happened in the first place.’
Facebook doesn’t know whether the accounts were misused, and hasn’t yet found any evidence of them being misused.