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Facebook Vulnerability Reflected File Download

Before starting with the write up i want to share the response that i got from facebook after reporting the bug.

Hi Rio,

Thank you for sharing this information with us. Although this issue does not qualify as a part of our bounty program we appreciate your report. We will follow up with you on any security bugs or with any further questions we may have.

I will let you guys decide if its a vulnerability or not.
Lets begin.

The vulnerability existed and still exists at

The vulnerability exists because the api reflects  data from the url and since we can inject a malicious payload.

Visiting the following url:

Since the data is reflected our main goal is to to make this get saved as a file.

Facebook did not have a content-disposition so our way to download is to use html5 download attribute.

Lets create a html file. ("test.html") and put the following content.

<a href=';/test.bat;"||calc.exe||?callback=random' download="test.bat">Download</a>

Now lets open the test.html and click download.

Basically we downloaded a bat file with our injected payload from the facebook website.


Rio Sherri

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