Forgotten payload borks support call

Domain registrar GoDaddy has patched a blind XSS vulnerability in its customer support that could have allowed access to GoDaddy accounts.
Uber security man Matthew Bryant (@IAmMandatory) reported in a personal capacity the bug he says was located in an internal support panel.

A payload he uploaded and then forgotten had fired during a legitimate support call he placed to GoDaddy, as the officer attempted to remediate his problem.
The payload was insecurely reflected onto a support page, breaking it.
“While using GoDaddy I noticed that my first and last name could be set to an XSS payload,” Bryant says.
“It was then (during the call) my phone vibrated twice indicating … notifications that my previously planted XSS payloads had fired.
“… my XSS payload borked the JSON displayed in the webpage body and escaped the script type=”text/javascript block [which] caused the XSS payload to fire but broke the webpage that the support agent was viewing.”
Bryant says the vulnerability meant an attacker could run any action that a GoDaddy customer rep could in what could have caused mayhem for customer accounts.
It took GoDaddy about four months to fix the hole after it brought Bryant into its private bug bounty program, and then claimed the vulnerability was a duplicate.
To make a physical comparison, blind XSS payloads act more like mines which lie dormant until someone triggers them.
Bryant says the vulnerability class is missed often in security tests.
“This flavour of XSS is often missed by penetration testers due to the standard alert box approach being a limited methodology for finding these vulnerabilities,” he says. “When your payloads are all script>alert(1)</script you’re making the assumption that the XSS will fire in your browser, when it’s likely it will fire in other places and in other browsers.”
Bryant recommends preventing payloads from being stored which goes beyond typical XSS remediation and affords improved security.
“When you do proper output encoding, you have to do it on every system which pulls data from your data store. However, if you simply ensure that the stored data is clean you can prevent exploitation of many systems because the payload would never be able to be stored in the first place.”
The bug is one of a series the hacker will post to his blog after respective vendors have applied fixes. ®

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