Unvalidated Redirects/ Open Redirect Vulnerability on VK Oauth Login

Hi VK,

Here is Shaifullah Shaon (Black_EyE), An Ethical Hacker.
a white hat cyber security researcher from Bangladesh reporting a serious
[3'rd ranking in OWASP] security vulnerability on your system.

I faced a technical security bug called "Unvalidated_Redirects/ Open Redirect Vulnerability on VK Oauth Login".


Description of Vuln:
Unvalidated redirects and forwards are possible when a web application accepts untrusted input that could cause the
web application to redirect the request to a URL contained within untrusted input. By modifying untrusted URL input
to a malicious site, an attacker may successfully launch a phishing scam and steal user credentials. Because the server
name in the modified link is identical to the original site, phishing attempts may have a more trustworthy appearance.
Unvalidated redirect and forward attacks can also be used to maliciously craft a URL that would pass the application’s
access control check and then forward the attacker to privileged functions that they would normally not be able to access.

Reference:

Unvalidated_Redirects/ Open Redirect Vulnerability:
1. https://www.owasp.org/index.ph....p/Unvalidated_Redire
2. http://www-01.ibm.com/support/....docview.wss?uid=swg2


Vuln Link: https://oauth.vk.com/authorize?client_id=-1&display=widget&redirect_uri=close.html&widget=4

POC url: https://oauth.vk.com/authorize?client_id=-1&display=widget&redirect_uri=https%3A%2f%2ffacebook.com&widget=4


Let's follow me,
1. Open Vuln Link in browser.
2. Change redirect_uri= to any site.
Now I try to https://google.com
3. press my user id and password for login,
5. And as you see I can redirect to any site.

Let's Check again with facebook.com
As you see, here redirect to anysite using this method.


Please See my Video Poc for understand clearly. Hopefully Those are Very critical issue.
Resolve those issue as soon as possible.

Here is proof as video concept (unlisted): https://youtu.be/CD7aUZFaTFo

Thank you
Shaifullah Shaon (Black_EyE)
shaon.durjoy@gmail.com

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