Facebook has awarded a researcher $10,000 for finding a serious vulnerability that could have been exploited remotely to delete any video from the social media website.
The flaw was disclosed on Monday by Dan Melamed, but it was reported to Facebook and patched last summer.
The researcher noticed that videos uploaded to a public event page on Facebook had an ID assigned to them. By uploading a video to an event page they controlled and replacing its ID with the ID of a targeted video, attackers could attach the victim’s video to their own post. Then, all they needed to do was delete the post on their own page, and the victim’s video would get deleted as well.
The ID of a video can be easily obtained from its URL. The attacker could intercept their own video upload request and replace the ID with the one of the targeted video. While the server responded with an error, the targeted video did get attached to the attacker’s post, allowing them to remove it from Facebook by deleting the post from their event page.
In addition to deleting a video, the same technique could have been used to disable comments on a targeted video. This could have been done by using the “Turn off commenting” option from the same dropdown menu as the “Delete Post” function.
It took Facebook only a few days to patch the vulnerability after receiving Melamed’s report. The social media giant decided to award the researcher a $10,000 bounty for his findings.
A similar flaw was found at around the same time by researcher Pranav Hivarekar. The method discovered by Hivarekar involved deleting a video after adding its identifier to a video included in a comment. Once the comment was deleted, the original video would be removed as well.
Facebook has so far paid out more than $5 million since the launch of its bug bounty program in 2011. The largest reward was given recently to Russian security researcher Andrey Leonov, who earned $40,000 for finding a way to exploit the ImageMagick vulnerability known as ImageTragick for remote code execution.