appspot is a sandbox/playground (whatevvvvveeeerrrr....) for apps...served by Google Frontend servers
breaking the logic without any whitepapers was quite easy...
I was proxy'ing my phone's addresses, through my PC's FIDDLER, this is a monthly routine,
since I need to keep up with all the junk push through publishers, through their new updated applications,
after I'm maintaining a list of all new PING, TRACKING, STATISTICS, ADVERTISEMENTS and plain old UNNEEDED JUNK,
I'm adding it to my sub-website hosts.eladkarako.com.
this time I've noticed something cool: using the host-name:
gaednsproxy.appspot.comwith a simple mimetype of
text/htmland short GET request:
request was made by some open source application named DroidFu:
GET http://gaednsproxy.appspot.com/?d=WTJ4cFpXNTBjek11WjI5dloyeGxMbU52YlE9PQ%3D%3D HTTP/1.1 Host: gaednsproxy.appspot.com User-Agent: Android/DroidFu Connection: close Connection: close
response was just an ip..
HTTP/1.1 200 OK Content-Type: text/html; charset=utf-8 Date: Thu, 11 Dec 2014 07:56:31 GMT Server: Google Frontend Cache-Control: private Alternate-Protocol: 80:quic,p=0.02 Connection: close 18.104.22.168
looks like an escaped-base64 argument, I've thought..
using my good old base64 enc/dec here
it was double enc/ in base64
WTJ4cFpXNTBjek11WjI5dloyeGxMbU52YlE9PQ%3D%3D (unescaped)-> WTJ4cFpXNTBjek11WjI5dloyeGxMbU52YlE9PQ== (first base64 decode)-> Y2xpZW50czMuZ29vZ2xlLmNvbQ== (second base64 decode)-> clients3.google.com
so this one was just a simple reverse hostname (clients3.google.com) to IP (22.214.171.124)...
double base64 looks kind'a overkill, fishy?? don'know..
from my experience it just may be a plain Anti-Fraud (Anti Man-In-The-Middle, Proxy/DNS Poisoning, etc...),
this way the IP is resolved through an external-server (a.k.a "safe place"), other then a risked machine (self Android device),
simple but effective....