Previous attachments can be referenced when creating a new report

How it was found

Hello When user upload file in comment to report, user can find file ID by two ways:

1. In preview mode - In response to POST method https://hackerone.com/attachments , answer will be something like this: -{"id":84577,"name":"mytestfile.png","size":32397} where file_ID = 84577 (for example)
2. If user post comment - At link to hackerone-attachments.s3.amazonaws.com, where file_ID is part of the link .../production/000/084/579/2b912875c3e8856c300dad535b732500f3c42c25/... In this case file_ID = 84579

When user post new report to some company on page: https://hackerone.com/[some_company]/reports/new in this page user's draft autosave by POST request: https://hackerone.com/security/reports/draft_sync

So if user post comment to report_1 and get file_ID_1, then he go to post new report to another company and generate autosave POST request by himself and change file_ID_new_report to file_ID_1 For example: report%5Btitle%5D=&report%5Bvulnerability_information%5D=Ffile_ID_1&report%5Battachment_ids%5D%5B%5D= file_ID_1&report%5Bforce%5D=false And, as you can see, set in param vulnerability_information Ffile_ID_1 (for example F84577)

Then user reload page with new report (F5), there two issues:

1. After Markdown parse he have direct link to file in comment (in our case file_ID_1 ): where comment to another report and another company. I think it's not so critical, but same experiment with file, which uploaded directly in initial report_1, is fail.
2. More Strange - file_1 in comment to report_1 is deleted! No more link to file in this comment.

My same experiment with file uploaded by another user (I make test account : @dkusliy_test) also is fail. Luckily))

Thanks and Best!