Homograph attack on redirect URL (https://chaturbate.com/external_link/?url)

How it was found

Hi There,

Hope you are doing good,

As i was just playing around with chaturbate.com and found that you guys does not have proper configuration for malicious script injection in website.

In Homograph attack basically attacker may able to inject some malicious script with URL.

Here i made homograph link for the ebay.com, when normal user see this link its look like normal simple text link but no its not simple link it's crafted homograph malicious script link so when user see this particular link user might be think that they are going to redirect on eBay.com but the fact that the link which add is malicious link and made from homograph encoding so when user click on this link user will redirect on some malicious website.

The IDN (Malicious link which i add in website) : https://xn--eby-7cd.com in looking it's look like eBay.com but when user click this link user will redirect on malicious website.

POC video {F323281}

POC URL https://chaturbate.com/external_link/?url=http://ebаy.com/

Prevention of this vulnerability

To prevent this vulnerability it would be safer to show the punycode version of the url so it would be apparent that something weird is going on. that is, show http://xn--eby-7cd.com/ instead of eBay.com.

you can see that how hackerone prevent this vulnerability

For instance, Here you can see that in hackerone if i am attaching punycode homograph URL but when you click on this link it will show you actual encryption URL of malicious URL : http://xn--eby-7cd.com/ - Click on this link and you will get know how to prevent this vulnerability or else you can also put prevention by adding validation on particular field for URL.

Reference

https://hackerone.com/reports/29491 https://hackerone.com/reports/175286

Please let me know if you want more information then,

Cheers, Ninjan

Impact

Attacker may able to inject any homograph URL in website and able to scratch any normal user to their malicious website.