Check if there are known vulnerabilities for the server version that is running.
The HTTP headers and cookies of the response could be very useful to identify the technologies and/or version being used.
webanalyze -host https://google.com -crawl 2
Default pages with interesting info
/robots.txt
/sitemap.xml
/crossdomain.xml
/clientaccesspolicy.xml
/.well-known/
Check also comments in the main and secondary pages.
CMS Scanners
If a CMS is used don't forget to run a scanner, maybe something juicy is found:
40X bypasser in Go. Methods from #bugbountytips, headers, verb tampering, user agents and more.
502 Proxy Error - SSRF
If any page responds with 502 Proxy Error, it's probably a bad configured proxy. If you send a HTTP request like: GET https://google.com HTTP/1.1 (with the host header and other common headers), the proxy will try toaccess google.com and you will have found a SSRF.
Protocol version
If using HTTP/1.1 try to use 1.0 or even test if it supports 2.0.
Other bypass techniques
Get the IP or CNAME of the domain and try contacting it directly.
Change the protocol: from http to https, or for https to http
Python3 HTTP Redirect
Good script to redirect HTTP traffic, this is useful for bypassing certain 301 Redirect checks or when using MSDT Follina.