Try to find username and password.
Webiste: http://simplesql.darkarmy.xyz/.
In the source we see the comment <!-- Try id as parameter -->
.
Injecting a simple ?id=1 or 2=2
gives us the response Username : LOL Password : Try
.
Trying ?id=2 or 2=2
gives us a difference response, Username : Try Password : another
, so I tried a few more till at http://simplesql.darkarmy.xyz/?id=9%20or%202=2
you get the flag.
darkCTF{it_is_very_easy_to_find}