We have to access
This kind of internet explorer does not exists, but we can trick the website into thinking that we are using it.
If we access this website with firefox using linux we request the website with the following user agent:
curl 'https://internet-explorer.knping.pl/' --compressed -H 'User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:109.0) Gecko/20100101 Firefox/115.0' -H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8' -H 'Accept-Language: en-US,en;q=0.5' -H 'Accept-Encoding: gzip, deflate, br' -H 'Alt-Used: internet-explorer.knping.pl' -H 'Connection: keep-alive' -H 'Upgrade-Insecure-Requests: 1' -H 'Sec-Fetch-Dest: document' -H 'Sec-Fetch-Mode: navigate' -H 'Sec-Fetch-Site: none' -H 'Sec-Fetch-User: ?1' -H 'TE: trailers'
We now have to change Firefox's user agent to the one of internet explorer. We can look this up at whatismybrowser and figure out that it is:
Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 5.1; Trident/4.0)
If we combine both we get the following curl command:
curl 'https://internet-explorer.knping.pl/' --compressed -H 'User-Agent: Mozilla/4.0 (compatible; MSIE 8.0; Linux; Trident/4.0)' -H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8' -H 'Accept-Language: en-US,en;q=0.5' -H 'Accept-Encoding: gzip, deflate, br' -H 'Connection: keep-alive' -H 'Upgrade-Insecure-Requests: 1' -H 'Sec-Fetch-Dest: document' -H 'Sec-Fetch-Mode: navigate' -H 'Sec-Fetch-Site: same-origin' -H 'Sec-Fetch-User: ?1' -H 'TE: trailers' -H 'Alt-Used: internet-explorer.knping.pl' -H 'Pragma: no-cache' -H 'Cache-Control: no-cache'
And we receive the flag: