How Security Researcher Found Stored XSS in Outlook And Got 1000 USD Bounty

Bug Bounty Earn

Bug Bounty- $1,000 USD In 5 Minutes For Stored XSS In OUTLOOK.COM

Security researcher Omar Espino got the Bug Bounty from Microsoft and shared the Proof Of Concept (POC) with us, he wrote,

“I want to tell you a short story about Microsoft bug bounty program and why you can always check the basic payloads because you will surprise that some times will work:

SPOILER ALERT: I highly recommend Microsoft Bug Bounty Program, in my experience their program is much better compared with another big companies programs

Title: XSS Stored on (iOS) via doc file.
Product / URL: ​ iOS browser (Google chrome)

Report sent via [email protected]

Hi ​Microsoft Security team.

I’ve found a XSS ​stored ​ in​ ​ ​in iOS ​ browsers via msoffice (ppt) file.


1.- Create a msoffice document per example a power point presentation with an hyperlink pointing to the URL address “javascript:prompt(document.cookie)” and save as “PowerPoint presentation 97-2003 Presentation”, Is very important save the doc as 97-2003, if you don’t save the document as this version the bug reproduction may not work.

MS Office Doc POC

2.- Login ​in​ to ​ ​(outlook email)​, upload to msoffice ppt file ​and send the file via email.

3.- ​ Login into ​ ​(outlook email)​ in Google chrome iOS browser, open the email with the special crafted document, click the attachment and then click download, after that the document ppt will render in Google chrome ​,​ ​then click the hyperlink and see the XSS (shows up the document.cookie). ​

Something important to highlight is: At this time you have a “magic” link that points directly to the ppt special crafted document. ​

​4​ .- Open the link directly ​in Chrome iOS browser , click the hyperlink and ​ see​ the XSS (shows up ​again ​ the document.cookie) ​, ​ if you open the link in any iOS browser like Safari, Firefox, Chrome, Opera the XSS works, you just need to be logged in your ​outlook account, only works in iOS).

MS Office Doc XSS POC


Stored XSS allows an attacker to embed a malicious and arbitrariness scripts into a vulnerable page, which is then executed when a victim views the page.


  • iPhone 6 – iOS v11.2.5.
  • ​Safari Latest version
  • Google Chrome Latest version
  • My personal email account and all testing was sending emails to myself.

Microsoft HOF (November 2018):

Report Timeline

  • 21 Feb 2018: Sent the report to [email protected]
  • 21 Feb 2018: Got confirmation from Microsoft team and team begin the investigation
  • 23 Mar 2018: Microsoft team ask for some details
  • 23 Mar 2018: Sent details to Microsoft team
  • 26 Jul 2018: Update from the team that the investigation was still in progress
  • 07 Nov 2018: Update from the team that saying that it appears that the submission qualifies for Bounty
  • 26 Nov 2018: Microsoft Reward paid through their payment system – [Profit]
  • 04 March 2019: Ask for disclose permission
  • 14 March 2019: Disclose permission granted from Microsoft team”

We like to congratulate to Omar Espino for its great find.

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