Security Experts:

Facebook Pays Out $40,000 for Account Takeover Exploit Chain

Social media giant Facebook on Thursday announced a new payout guideline to help vulnerability hunters better understand its bounty decisions related to given bugs.

Specifically, the new guideline covers security issues in contact point visibility settings in the "Who can look you up using the email address or phone number you provided" section.

Per the new guideline, Facebook will shell out a maximum of $10,000, “for reports that demonstrate the ability to obtain one or more contact points (i.e. phone number or email) from an account that has their settings for ‘Who can look you up using the email address or phone number you provided’ configured to ‘Only Me’ or ‘Friends’,” the social medial platform explains.

Facebook also notes that, when determining the amount to be rewarded to a researcher, it takes into consideration factors such as whether user interaction is required for the exploit, whether the attacker needs to be in a privileged position, and whether the attack applies to Workplace or not. The fewer mitigating factors are found, the higher the awarded bounty reward.

Under the newly disclosed guidelines and partially under the company’s account takeover guideline, a security researcher was awarded a $40,000 bounty for a report describing how a pair vulnerabilities can be chained to take over user accounts.

One of the vulnerabilities allowed for the researcher to discover the user ID of a valid user email or phone number, which would then be used to trigger a password reset for the user ID through brute-forcing the verification code that Facebook uses to validate the phone number contact point.

[ READ: Facebook Paid Out $50K for Vulns Allowing Access to Internal Systems ]

The social platform says that it found no evidence of malicious abuse of this scenario. The issues have already been fixed.

Another researcher, Facebook says, was awarded a $15,000 bounty to a researcher who discovered that, for newly-added phone numbers and emails, the default setting was set to "Friends" and not to "Only Me," although this was shown to the user when submitting contact points.

“We fixed both the email and phone number bugs and corrected these settings for people whose visibility configuration we believe was impacted. We rolled out a fix across our products to prevent similar issues in the future and based our bounty payout on the maximum potential impact. We found no evidence that this information was the subject of scraping,” Facebook says.

The announcement comes roughly one week after the social media platform introduced Researcher Collaboration Payouts, where bounty payouts may be split between multiple researchers who may have worked together for a single submission. These payouts should cover the scenarios where researchers teams work together to identify complex bug chains that have high security impact.

Related: Facebook Paid Out $50K for Vulnerabilities Allowing Access to Internal Systems

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