Facebook has patched a vulnerability that attackers could have abused to delete any user’s video off the social media platform.
Security researcher Dan Melamed came across the vulnerability in June 2016. The bug is some ways similar to a vulnerability discovered by another researcher around the same time. There’s just one major exception.
Melamed explains in a blog post:
“Instead of attaching the victim’s video to a comment, I discovered a way to attach the video to an event post. When you delete an event post it also deletes the attached video.”
The security researcher exploited the flaw by first creating a public event. On the Discussion part of the event, he uploaded a video and intercepted the POST request using Fiddler.
This request, which looks something like
https://www.facebook.com/media/upload/photos/composer/?av<Profile ID>&dpr=1, comes with
composer_unpublished_photo=<Video ID>; as one of its parameters.
The crux of the vulnerability rested with the Video ID value. All someone needed to do was change the Video ID to any other video on the social media platform. Sure, Facebook would then have responded with a server error, but the new video would have displayed just fine.
From there, an attacker could have simply deleted the video. Doing so would have removed the video from the social networking site.
But that’s not all Melamed found out. As he notes:
“You will also notice in the dropdown section that there is the option to ‘Turn off commenting’. This allows you to disable commenting on the video of your choice.”
You can view a demo of the exploit code in action below.
Computer criminals might have any number of reasons for deleting a video off Facebook. Perhaps they work for a company and want to sabotage a marketing campaign of one of their employer’s competitors. Alternatively, they might just be jerks and so don’t care if the world doesn’t see your toddler taking their first few steps.
Fortunately, we don’t worry to have worry about this vulnerability any longer. Facebook, which took two weeks at the start of 2017 to remove an upsetting video, patched the vulnerability a short time after Melamed reported the flaw to its security teams. A $10,000 bug bounty award shortly followed after that.
Responsible disclosure at its best. There’s nothing like it.
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