HomeAdvisor Pro - (EntityHash) Auth Bypass Vulnerability

Document Title:
===============
HomeAdvisor Pro - (EntityHash) Auth Bypass Vulnerability


References:
===========
http://www.vulnerability-lab.com/customer/get_content.php?id=1929

Video: https://www.youtube.com/watch?v=PQsCIOyESIo

Advisory: https://www.vulnerability-lab.com/get_content.php?id=1557



Release Date:
=============
2018-07-19


Vulnerability Laboratory ID (VL-ID):
====================================
1929


Common Vulnerability Scoring System:
====================================
9.4


Vulnerability Class:
====================
Authentication Bypass


Current Estimated Price:
========================
5.000€ - 10.000€


Vulnerability Disclosure Timeline:
==================================
2018-07-19: Non-Public Disclosure (Vulnerability Laboratory - Shared Customer Research Feed)


Discovery Status:
=================
Published


Exploitation Technique:
=======================
Remote


Severity Level:
===============
Critical


Authentication Type:
====================
Pre auth - no privileges


User Interaction:
=================
No User Interaction


Disclosure Type:
================
Bug Bounty Program


Technical Details & Description:
================================
The video demonstrates a zero-day vulnerability in the homeadvisor pro web-application of the dhs company. The vulnerability is located in 
the entityHash= parameter of homeadvisory pro. When an attacker changes the value entityHash= to the victim entityHash= you will login without 
confirm secure. By usage of google or other crawlers we are able to capture the entityHash value of homeadvisor pro users. The same vulnerability 
typus was disclosed first by our team to the microsoft bug bounty yammer program in 2013. The vulnerability is that there is no second auth approval 
for the entityhash which can results in a takeover of another account by usage of an auth bypass in connection with the hash.


Credits & Authors:
==================
Vulnerability-Lab [[email protected]] - https://www.vulnerability-lab.com/show.php?user=Vulnerability-Lab


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=========================
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