Why isn't this XSS working?
I'm learning DOM XSS and I have this code :
<html>
<body>
Select your language:
<select>
<script>
document.write("<OPTION value=1>"+document.location.href.substring(document.location.href.indexOf("default=")+8)+"</OPTION>");
document.write("<OPTION value=2>English</OPTION>");
</script>
</select>
</body>
</html>
but I don't understand why this payload doesn't trigger any XSS :
t.html?default=test</option><img src=x onerror=alert(1)/>
It looks like the symbols are encoded and I don't understand why...
I took the script from https://www.owasp.org/index.php/DOM_Based_XSS so I guess it's vulnerable but I don't know how to exploit it...
xss
edited yesterday
Alex Probert
3191215
asked yesterday
NeolexNeolex
10219
add a comment |
I'm learning DOM XSS and I have this code :
<html>
<body>
Select your language:
<select>
<script>
document.write("<OPTION value=1>"+document.location.href.substring(document.location.href.indexOf("default=")+8)+"</OPTION>");
document.write("<OPTION value=2>English</OPTION>");
</script>
</select>
</body>
</html>
but I don't understand why this payload doesn't trigger any XSS :
t.html?default=test</option><img src=x onerror=alert(1)/>
It looks like the symbols are encoded and I don't understand why...
I took the script from https://www.owasp.org/index.php/DOM_Based_XSS so I guess it's vulnerable but I don't know how to exploit it...
xss
edited yesterday
Alex Probert
3191215
asked yesterday
NeolexNeolex
10219
add a comment |
I'm learning DOM XSS and I have this code :
<html>
<body>
Select your language:
<select>
<script>
document.write("<OPTION value=1>"+document.location.href.substring(document.location.href.indexOf("default=")+8)+"</OPTION>");
document.write("<OPTION value=2>English</OPTION>");
</script>
</select>
</body>
</html>
but I don't understand why this payload doesn't trigger any XSS :
t.html?default=test</option><img src=x onerror=alert(1)/>
It looks like the symbols are encoded and I don't understand why...
I took the script from https://www.owasp.org/index.php/DOM_Based_XSS so I guess it's vulnerable but I don't know how to exploit it...
xss
edited yesterday
Alex Probert
3191215
asked yesterday
NeolexNeolex
10219
I'm learning DOM XSS and I have this code :
<html>
<body>
Select your language:
<select>
<script>
document.write("<OPTION value=1>"+document.location.href.substring(document.location.href.indexOf("default=")+8)+"</OPTION>");
document.write("<OPTION value=2>English</OPTION>");
</script>
</select>
</body>
</html>
but I don't understand why this payload doesn't trigger any XSS :
t.html?default=test</option><img src=x onerror=alert(1)/>
It looks like the symbols are encoded and I don't understand why...
I took the script from https://www.owasp.org/index.php/DOM_Based_XSS so I guess it's vulnerable but I don't know how to exploit it...
xss
xss
edited yesterday
Alex Probert
3191215
asked yesterday
NeolexNeolex
10219
edited yesterday
Alex Probert
3191215
asked yesterday
NeolexNeolex
10219
edited yesterday
Alex Probert
3191215
edited yesterday
Alex Probert
3191215
edited yesterday
Alex Probert
3191215
3191215
asked yesterday
NeolexNeolex
10219
asked yesterday
NeolexNeolex
10219
asked yesterday
NeolexNeolex
10219
10219
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
It doesn't work because the payload is URL-encoded.
If you navigate to
https://example.com/?foo=<>"
you will see the literal characters <>" in your URL bar, but the browser has actually requested
https://example.com/?foo=%3C%3E%22
. That is, your browser always URL-encodes some characters in the query string, including quotes and angle brackets.
So, if you access location.href via JS, the payload in your example will be returned as
test%3C/option%3E%3Cimg%20src=x%20onerror=alert(1)/%3E
. This does not produce any HTML tags unless you URL-decode it first.
Note: As far as I know, all modern browsers now behave that way, but historically, some implementations have implicitly URL-decoded values for the location interface. In these browsers, your attack would have worked.
answered yesterday
ArminiusArminius
37.8k13123120
Oh I see... Ok ! Thank you so much ! So this webpage is not vulnerable anymore ?
– Neolex
yesterday
2
There may still be browsers that let you sneak literal quotes and angle brackets somewhere in the URL where they don't get URL-encoded. But I believe your example isn't vulnerable in modern Chrome and Firefox.
– Arminius
yesterday
Ok ! Thanks a lot !
– Neolex
yesterday
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
It doesn't work because the payload is URL-encoded.
If you navigate to
https://example.com/?foo=<>"
you will see the literal characters <>" in your URL bar, but the browser has actually requested
https://example.com/?foo=%3C%3E%22
. That is, your browser always URL-encodes some characters in the query string, including quotes and angle brackets.
So, if you access location.href via JS, the payload in your example will be returned as
test%3C/option%3E%3Cimg%20src=x%20onerror=alert(1)/%3E
. This does not produce any HTML tags unless you URL-decode it first.
Note: As far as I know, all modern browsers now behave that way, but historically, some implementations have implicitly URL-decoded values for the location interface. In these browsers, your attack would have worked.
answered yesterday
ArminiusArminius
37.8k13123120
Oh I see... Ok ! Thank you so much ! So this webpage is not vulnerable anymore ?
– Neolex
yesterday
2
There may still be browsers that let you sneak literal quotes and angle brackets somewhere in the URL where they don't get URL-encoded. But I believe your example isn't vulnerable in modern Chrome and Firefox.
– Arminius
yesterday
Ok ! Thanks a lot !
– Neolex
yesterday
add a comment |
It doesn't work because the payload is URL-encoded.
If you navigate to
https://example.com/?foo=<>"
you will see the literal characters <>" in your URL bar, but the browser has actually requested
https://example.com/?foo=%3C%3E%22
. That is, your browser always URL-encodes some characters in the query string, including quotes and angle brackets.
So, if you access location.href via JS, the payload in your example will be returned as
test%3C/option%3E%3Cimg%20src=x%20onerror=alert(1)/%3E
. This does not produce any HTML tags unless you URL-decode it first.
Note: As far as I know, all modern browsers now behave that way, but historically, some implementations have implicitly URL-decoded values for the location interface. In these browsers, your attack would have worked.
answered yesterday
ArminiusArminius
37.8k13123120
Oh I see... Ok ! Thank you so much ! So this webpage is not vulnerable anymore ?
– Neolex
yesterday
2
There may still be browsers that let you sneak literal quotes and angle brackets somewhere in the URL where they don't get URL-encoded. But I believe your example isn't vulnerable in modern Chrome and Firefox.
– Arminius
yesterday
Ok ! Thanks a lot !
– Neolex
yesterday
add a comment |
It doesn't work because the payload is URL-encoded.
If you navigate to
https://example.com/?foo=<>"
you will see the literal characters <>" in your URL bar, but the browser has actually requested
https://example.com/?foo=%3C%3E%22
. That is, your browser always URL-encodes some characters in the query string, including quotes and angle brackets.
So, if you access location.href via JS, the payload in your example will be returned as
test%3C/option%3E%3Cimg%20src=x%20onerror=alert(1)/%3E
. This does not produce any HTML tags unless you URL-decode it first.
Note: As far as I know, all modern browsers now behave that way, but historically, some implementations have implicitly URL-decoded values for the location interface. In these browsers, your attack would have worked.
answered yesterday
ArminiusArminius
37.8k13123120
It doesn't work because the payload is URL-encoded.
If you navigate to
https://example.com/?foo=<>"
you will see the literal characters <>" in your URL bar, but the browser has actually requested
https://example.com/?foo=%3C%3E%22
. That is, your browser always URL-encodes some characters in the query string, including quotes and angle brackets.
So, if you access location.href via JS, the payload in your example will be returned as
test%3C/option%3E%3Cimg%20src=x%20onerror=alert(1)/%3E
. This does not produce any HTML tags unless you URL-decode it first.
Note: As far as I know, all modern browsers now behave that way, but historically, some implementations have implicitly URL-decoded values for the location interface. In these browsers, your attack would have worked.
answered yesterday
ArminiusArminius
37.8k13123120
edited yesterday
answered yesterday
ArminiusArminius
37.8k13123120
answered yesterday
ArminiusArminius
37.8k13123120
answered yesterday
ArminiusArminius
37.8k13123120
37.8k13123120
Oh I see... Ok ! Thank you so much ! So this webpage is not vulnerable anymore ?
– Neolex
yesterday
2
There may still be browsers that let you sneak literal quotes and angle brackets somewhere in the URL where they don't get URL-encoded. But I believe your example isn't vulnerable in modern Chrome and Firefox.
– Arminius
yesterday
Ok ! Thanks a lot !
– Neolex
yesterday
add a comment |
Oh I see... Ok ! Thank you so much ! So this webpage is not vulnerable anymore ?
– Neolex
yesterday
2
There may still be browsers that let you sneak literal quotes and angle brackets somewhere in the URL where they don't get URL-encoded. But I believe your example isn't vulnerable in modern Chrome and Firefox.
– Arminius
yesterday
Ok ! Thanks a lot !
– Neolex
yesterday
Oh I see... Ok ! Thank you so much ! So this webpage is not vulnerable anymore ?
– Neolex
yesterday
Oh I see... Ok ! Thank you so much ! So this webpage is not vulnerable anymore ?
– Neolex
yesterday
2
2
There may still be browsers that let you sneak literal quotes and angle brackets somewhere in the URL where they don't get URL-encoded. But I believe your example isn't vulnerable in modern Chrome and Firefox.
– Arminius
yesterday
There may still be browsers that let you sneak literal quotes and angle brackets somewhere in the URL where they don't get URL-encoded. But I believe your example isn't vulnerable in modern Chrome and Firefox.
– Arminius
yesterday
Ok ! Thanks a lot !
– Neolex
yesterday
Ok ! Thanks a lot !
– Neolex
yesterday
add a comment |
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