(POC) Update business fyi message as Facebook page analyst

Description / Impact

In a FB5 there is an update related to COVID-19 which allow a page to pending there customer service as a result of Coronavirus, this action require high permission to be made on behalf the page but according to my testing I observe that it ‘s possible to update business fyi message with the analyst permissions.

This behavior is unexpected since the analyst permissions is generally read-only permissions.

Proof Of Concept / Reprosteps

  • Obtain the page ID
HTTP POST /api/graphql/?av=valueObtainedFromStepOne 
Host: facebook.com
  • Display a button that links to your own URL
HTTP POST /api/graphql/?av=valueObtainedFromStepOne 
Host: facebook.com
  • The business fyi message has been updated as analyst.

Coronavirus (COVID-19) Update From {page name}

Due to challenges caused by coronavirus (COVID-19), we’re providing our customers with extra support and resources

Visit {URL button}

13/08/2020: Report Sent
Triaged By Facebook after 10 hours.
25/08/2020: Patch confirmed by Facebook
27/08/2020: $750 Bounty awarded by Facebook

Security Researcher