Updated How to obfuscate JavaScript in Metasploit (markdown)

How-to-obfuscate-JavaScript-in-Metasploit.md

@@ -127,6 +127,8 @@ puts html
 
 The JSObfu class used to be ObfuscateJS' cousin, but it has been completely rewritten since September 2014, and packaged as a gem. The obfuscation is more complex and you can actually tell it to obfuscate multiple times. You also no longer have to manually specify what symbol names to change, it just knows.
 
+**Trying JSObfu in Rex**
+
 Let's get back to irb again to demonstrate how easy it is to use JSObfu:
 
 ```
@@ -187,6 +189,17 @@ And finally, let's try to obfuscate a few times to see how that goes:
 => window[String[((function(){var s=(function () { var r="e"; return r })(),Q=(function () { var I="d",dG="o"; return dG+I })(),c=String.fromCharCode(0x66,114),w=(function () { var i="C",v="r",f="omCh",j="a"; return f+j+v+i })();return c+w+Q+s;})())](('Urx'.length*((0x1*(01*(1*020+5)+1)+3)*'u'.length+('SGgdrAJ'.length-7))+(('Iac'.length*'XLR'.length+2)*'qm'.length+0)),(('l'.length*((function () { var vZ='k'; return vZ })()[((function () { var E="h",t="t",O="leng"; return O+t+E })())]*(0x12*1+0)+'xE'.length)+'h'.length)*(function () { var Z='uA',J='tR',D='x'; return D+J+Z })()[((function () { var m="th",o="g",U="l",Y="en"; return U+Y+o+m })())]+'lLc'.length),('mQ'.length*(02*023+2)+('Tt'.length*'OEzGiMVf'.length+5)),(String.fromCharCode(0x48,0131)[((function () { var i="gth",r="len"; return r+i })())]*('E'.length*0x21+19)+(0x1*'XlhgGJ'.length+4)),(String.fromCharCode(0x69)[((function () { var L="th",Q="n",$="l",I="g",x="e"; return $+x+Q+I+L })())]*('QC'.length*0x2b+3)+(01*26+1)))]((function(){var C=String[((function () { var w="rCode",j="mCha",A="fr",B="o"; return A+B+j+w })())]((6*0x10+15),('riHey'.length*('NHnex'.length*0x4+2)+4),(01*95+13),(1*('Z'.length*(0x1*(01*(0x3*6+5)+1)+18)+12)+46),(0x1*(01*013+6)+16)),JQ=String[((function () { var NO="ode",T="rC",HT="fromCha"; return HT+T+NO })())](('J'.length*0x54+17),(0x2*051+26),('TFJAGR'.length*('ymYaSJtR'.length*'gv'.length+0)+12),(01*0155+2),(0xe*'FBc'.length+2),(0x1*22+10),(3*(01*043+1)+11)),g=(function(){var N=(function () { var s='h'; return s })();return N;})();return g+JQ+C;})());
 ```
 
+Using JSObfu for module development
+
+When you are writing a module, you should not call Rex directly like the above examples. Instead, you should be using the ```#js_obfuscate``` method found in [JSObfu mixin](https://github.com/rapid7/metasploit-framework/blob/master/lib/msf/core/exploit/jsobfu.rb). When you're using JavaScript in your module, always do write it like this:
+
+```ruby
+# This returns a Rex::Exploitation::JSObfu object
+js = js_obfuscate(your_code)
+```
+
+Note that by default, even though your module is calling the #js_obfuscate method, obfuscation will not kick in unless the user sets the JsObfuscate datastore option. This option is an OptInt, which allows you to set the number of times to obfuscate (default is 0).
+
 ## Reference(s)
 
 https://community.rapid7.com/community/metasploit/blog/2011/07/08/jsobfu