Security Experts:

Google Rewards Researchers for YouTube Comment Theft Vulnerability

Google has patched a vulnerability in YouTube that could have been exploited to copy any comment from one video to another, researchers revealed on Wednesday.

The security hole was identified by Egypt-based researchers Ibrahim El-Sayed and Ahmed Aboul-Ela while analyzing the comment approval feature in YouTube.

YouTube users can allow all comments to be directly posted to their videos and channels, but they can also choose to only publish comments that have been reviewed and approved. When the “Hide all comments for review” option is enabled, YouTube users must go to and manually approve each of the comments they want published on their videos and channel.

Researchers discovered that when a comment is approved, a request containing a comment ID and a video ID is sent to YouTube’s servers. If the “video_id” parameter was manipulated, an error appeared. However, the “comment_id” could be replaced with the value of an existing comment.

“The original comment from the original video doesn’t get removed, and the author of the comment does not get notified that his comment is copied onto another video,” Aboul-Ela said in a blog post.

As demonstrated in a video published by the researchers, an attacker could have leveraged the vulnerability to copy any comment to their own video or channel simply by copying the “comment_id” of the targeted comment and adding it to a comment approval POST request.

“Imagine for instance a celebrity or public figure leaving a comment on some video on Youtube saying ‘Wow, This is an Amazing Video’. You then come along, exploit that vulnerability, and quite simply make this comment appear on your own video instead,” Aboul-Ela explained.

The vulnerability was reported to the Google Security Team on March 25 and it was fixed on March 31. Google awarded the researchers $3,133.7 for their findings.

This isn’t the only interesting YouTube vulnerability reported over the past weeks. Last month, Russian security researcher Kamil Hismatullin identified a bug that could have been exploited by an attacker to remove any video from the website. Google awarded Hismatullin $5,000 for reporting the flaw.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.