add a "reflected XSS" vulnerability #3
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This commit adds a URL parameter, 'name', that is used in a welcome message if it exists. The name is unsanitized and so can include JS and thus cause an XSS that runs on the client side but does not exist on the server side (i.e., a "reflected XSS"). The behavior of the system is unchanged if you go to the bare URL, e.g., http://127.0.0.1:5000/ -- however, if you add a 'name' parameter to the URL, e.g., http://127.0.0.1:5000?name=Peter it will display a welcome message between "XSS Demo" and "Read, Search, and Post Comments". The name parameter can contain JS, e.g.: http://127.0.0.1:5000?name=Peter<script>alert("boo")</script> ... and this JS will run in the page.
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This commit adds a URL parameter, 'name', that is used in a welcome message if it exists. The name is unsanitized and so can include JS and thus cause an XSS that runs on the client side but does not exist on the server side (i.e., a "reflected XSS").
The behavior of the system is unchanged if you go to the bare URL, e.g., http://127.0.0.1:5000/ -- however, if you add a 'name' parameter to the URL, e.g., http://127.0.0.1:5000?name=Peter it will display a welcome message between "XSS Demo" and "Read, Search, and Post Comments".
The name parameter can contain JS, e.g.:
http://127.0.0.1:5000?name=Peter<script>alert("boo")</script>
... and this JS will run in the page.
Sanitization should be the same in either case, i.e., setting autoescape to true in the template.