Conditional Malicious iFrame Targeting WordPress Web Sites

We have an email, labs@sucuri.net where we receive multiple questions a day about various forms of malware. One of the most common questions happen when our Free Security Scanner, SiteCheck, detects a spam injection or a hidden iframe and the user is unable to locate the infection in the source code. It’s not until we explain what Conditional Malware is that they start to understand it’s implications and more importantly how it works. If you’re unfamiliar, conditional malware is very common these days, as the name implies it’s based on a set number of conditions that determine whether a payload (i.e., the malware) presents itself to the browser. It’s employed because it’s easier to evade scanners and reduces the odds of detection by spreading the impact.


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Website Security – Compromised Website Used To Hack Home Routers

What if we told you that a compromised website has the ability to hack your home router?

Yesterday we were notified that a popular newspaper in Brazil (politica.estadao.com.br) was hacked and loading several iFrames. These iFrames were trying to change the DNS configuration on the victim’s DSL router by Brute Forcing the admin credentials.

Sucuri - Politica NewsPaper Twitter Notification

Sucuri – Politica NewsPaper Twitter Notification

As you can see in the image, the payload was trying the user admin, root, gvt and a few other usernames, all using the router default passwords. Hours after being notified the website was still compromised, so we decided to dig a little deeper.

Below is the payload chain:


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Website Malware: Mobile Redirect to BaDoink Porn App Evolving

Recently, we wrote about a malware redirection on this blog where the malware was causing compromised sites to redirect their visitors to pornographic content (specifically, the BaDoink app). You can read more about what we found by going to our previous blog post.

As described in the original post, some particular files were infected (examples were the index.php, wp-config.php and others). We thought that was enough malware for one app. However, while we were working on an infected site today, we found a new malware injection causing this redirection.

Since all of the sites web files were clean and we didn’t find any suspicious Apache modules or binaries, it took a while for us to figure the problem out. However, it became much more clear once we investigated the PHP binary and found some suspicious entries.

First, after running the php -i command (which displays full php info), I got the location of the main php.ini configuration file. When I took a look at it, I saw the following suspicious entry:

php_prepend1

I was actually searching for the auto_append_file entry (because it is a very commonly used malware entry), but this time, auto-append was empty. Right above it, however, there was an auto_prepend_file entry that had some files assigned and it was this /etc/.loger.php, that looked very suspicious.

Here’s what we found when we opened the file:

php_prepend2

After deobfuscating it we could confirm that it was malicious and that it contained a redirection to the infamous Porn app because it used the exact same code responsible for inserting the malicious JavaScript redirects to the documents (based on the User Agent). The solution was to remove the php.ini entry, and remove the file itself, and then to restart the apache server.

Be careful because simply removing the file will cause a crash of your site and will lead to a 500 internal server error, which is why Apache needs to be restarted. However, if you want to schedule the restart for a more appropriate time, removing all of the content from this malicious file (.loger.php in this case) would do the trick and then you can remove it after restarting your apache.

What did we learn

We already knew this, but there is a lot of money to be made by redirecting website links to porn and some malicious agents will do this by hacking legitimate links and websites. In this case, there is still a lot of traffic being driven specifically to Badoink’s App. It’s important to remember that, if you hear reports of visitors being redirected and can’t get redirected yourself, your site is still at risk as much of the malware we’ve seen is conditional. Finally, remember that we can prevent, detect and fix sites built on any platform (examples: WordPress, Joomla, Drupal) so if you’re having a hard time getting rid of the malware or any symptoms of malware, sign up for a plan and our team will clean your site today.

Stay safe and keep your eyes open!

Website Malware – Mobile Redirect to BaDoink Porn App

A few weeks ago we reported that we were seeing a huge increase in the number of web sites compromised with a hidden redirection to pornographic content. It was a very tricky injection, with the redirection happening only once per day per IP address and only if the visitor was using a mobile device (IPhone, Android and a few others).

These types of injections are called conditional redirections because certain conditions need to be met for them to redirect visitors. They are not always present and the malware authors try very hard to hide them from the website owner. The malware code looks for logged in cookies to try to identify whether or not someone is managing the site and then attempts to never redirect someone who is logged in. Finally, if a visitor gets redirected once, the malware will not redirect them again. The goal for the malware author is for visitors to not report something going wrong with a website. In this example, if you were to visit an infected site, you’d be redirected, but from your point of view, maybe it was just something weird so you retype the url and now you aren’t redirected. Since everything is working normally now, you decide not to report it and the malware lives on.

As you can imagine, this sort of malware can be difficult to troubleshoot. In fact, very often webmasters think it’s a typo and move on instead of investigating what happened. For that reason, most sites remain compromised, so if anyone ever complains that your site redirecting to “instabang.com” or a Badoink Porn App, it is very likely your site is hacked.


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SiteCheck Extended – Making It Easier to Scan Your Websites

Sucuri SiteCheck is our free website malware scanner that crawls any website to detect signs of Malware injections, SEO Spam, Blacklisting, Defacement and other similar indicators of a compromised website.

It is widely used by Webmasters to verify if their sites have not been compromised or blacklisted. And now we’re extending it to other platfroms, by making it easier to use from multiple devices and products.

Please be sure to take a minute to understand how SiteCheck works, then leverage it on your own web properties to show visitors that your site is malware-free.

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Ad Violations: Why Search Engines Won’t Display Your Site If it’s Infected With Malware

As your site’s webmaster, have you ever seen an e-mail from Google like this:

Hello,

We wanted to alert you that one of your sites violates our advertising policies. Therefore, we won’t be able to run any of your ads that link to that site, and any new ads pointing to that site will also be disapproved.

Here’s what you can do to fix your site and hopefully get your ad running again:

1. Make the necessary changes to your site that currently violates our policies:
Display URL: site.com
Policy issue: Malware
Details & instructions:

2. Resubmit your site to us, following the instructions in the link above….

If so, you know the potential downside risk this poses for your website. In their own words, Google says,

In some cases, you may be unaware that you have malware on your site. But to protect the safety and security of our users, we stop all ads pointing to sites where we find malware.

In essence, Google and Bing care about their searchers more than your business so, to protect their customers, they’ll shut your website out of Adwords and Bing Ads and will return your site less in organic searches.

Often overlooked in the search business is the role of the actual search engine in the ad placement process. These are businesses that specialize in creating algorithms to show relevant search results, assigning quality scores to your landing pages and placing your actual ads. A lot goes into the process, but in all cases, the key for the search engine is to show relevant search results (including ads) that keep people using their search engine. It is in this spirit that search engines like Google and Bing reserve the right to refuse your ads. This is especially true if they have any reason to believe that your site may be infected with malware–including viruses, worms, spyware, and Trojan Horses–or is being used in phishing schemes.

From the search engine’s perspective, this makes perfect sense. Searches are their lifeblood and there are other search engines a person could use to find websites. By showing your ads or returning your site organically in a search, they are tacitly telling the searcher, “We found these sites to be relevant to you.” If they start sending you to sites that are potentially harmful, then a searcher could, potentially, switch search engines.

However, knowing why search engines work as they do doesn’t make it easier to be a webmaster when a site is hacked. Luckily, our clean up and malware removal tools as well as our de-blacklisting service are just a click away.

Or, better yet, keep yourself from ever getting an email like the one above from Bing or Google. Instead, protect your site, and business, from potential problems stemming from malware, blacklisting or phishing and look into protecting your site with a website application firewall like our CloudProxy WAF .

Highly Effective Joomla Backdoor with Small Profile

It feels like every day we’re finding gems, or what appear to be gems to us. We try to balance the use of the term, but I can’t lie, these are truly gems. The things they are doing, and by they I mean the attackers, are in some instance ingenious. I think you’ll agree that this case falls into that category.

In short, this is a highly effective backdoor that carries little profile, making it Hight Speed Low Drag.

Understanding Attackers

As we’ve discussed in the past, most attackers have a pretty standard workflow when compromising websites. Here’s that process in it’s simplest form:

  1. Identify point of entry / weakness
  2. Exploit the entry / weakness
  3. Ensure that they can retain access
  4. Cover your tracks

I agree, nothing earth shattering, but it does help us understand what it is we need to be looking for.

Many will make the argument that a site is not clear if you haven’t performed some level of forensics to understand what happened. Often this same analysis will lend itself to items 3 and 4 in the list. Reverse engineering their attempts to clean up their traces and finding those backdoors, diamonds in the ruff.

Unfortunately, this level of forensics is not for everyone and contrary to popular belief it’s not as simple as looking for simple obfuscation. No, these days the backdoors are becoming highly sophisticated, making use of built-in functions and carry little trace of what you might consider to be traditional backdoors.

What many also don’t realize is how important the third step is. If done correctly, the attacker is able to bypass all your access control mechanisms, i.e., logins like administrator and FTP, and work right off your server with little hesitation.

This post is an example of that, for instance take into consideration these two images:

Image #1

Sucuri-Joomla-Backdoor-I

Image #2

Sucuri-Joomla-Backdoor-II

Can you pinpoint the difference or the backdoor? Is there a backdoor?

Joomla Specific Backdoor

The images above are an example of what we recently found and the purpose of this post.

Yes, I agree, it’s unfair for us to ask you to pinpoint the difference in the images; besides, the total change is no greater than 304 bytes.

But for those keen eyes, you probably noticed the difference in the if-clause, here specifically:

if (!in_array($format, $allowable) && !in_array($format,$ignored))

Versus this:

if ($format == '' || $format == false || (!in_array($format, $allowable) && !in_array($format,$ignored)))

For those that are completely lost, it all comes down to how the $format variable is created. For that we have to look here:

$format = strtolower(JFile::getExt($file['name']));

This tell us that the variable is getting the file’s extension using a Joomla native function called getExt. This function does this:

function getExt($file) {
$chunks = explode('.', $file);
$chunksCount = count($chunks) - 1;

if($chunksCount > 0) {
return $chunks[$chunksCount];
}

return false;
}

This in turn breaks the file name into pieces based on the positions of the dot, returning false if there are not dots. If everything is ok it returns the latest group after the last dot, i.e., the extension.

This is where the canUpload function will check if the extension is part of the allowed ones or not. This goes back to the very first if clause shared above.

In the second set, you see two additional conditions, if $format is false or if it’s empty. That’s then followed by another .OR. operator just before checking if the extension is allowed.

In these cases, if the extension is empty or if it’s false or allowed, the file can be uploaded. This and nothing is the same thing, right?

Wow, that one hurt my head too, sorry.. but hang in there.

In order to make the $format false, or empty, the attacker would need to add a trailing dot to the end of the file, like backdoor.php.. But it’s not that simple, the upload alone won’t make it useable.

That brings you to the next obvious question, “Fio, if it’s not usable why the heck did you take us down riddle man?” Glad you asked…

First, because I probably had one too many beers while writing this.

Second, it comes down to this code:

function makeSafe($file) {
// Remove any trailing dots, as those aren't ever valid file names.
$file = rtrim($file, '.');
$regex = array('#(\.){2,}#', '#[^A-Za-z0-9\.\_\- ]#', '#^\.#');
return preg_replace($regex, '', $file);
}

I mean seriously, have you ever seen code in better shape than this? The lines, the logic, even the commenting..

// Remove any trailing dots, as those aren’t ever valid file names.

And you have to appreciate the irony in the function name, makeSafe. Make safe a backdoor that is going to do anything but make your website safe.

Here is the kicker, for those that didn’t catch it, this is a valid function inside ./libraries/joomla/filesystem/file.php, a core file of Joomla. This function, by design, cleans out all odd characters from a filename and returns a safe filename. Sound familiar? Remember that trailing dot? Pretty sure that’s unsafe, Joomla core agrees with us, as such it does what it’s supposed to do, makes a previously unsafe file, safe. Ain’t that something?

Perfect example of a feature that gets abused for bad when it was designed for good.

The Ever Evolving Landscape

I chose to share this little gem with the world because it talks volumes to the evolution in the attacks that we’re seeing. The website security market has turned into a gold rush as of late, but with that growth we have seen new innovation in the way attackers are 1) attacking websites and 2) how they’re retaining control of those same websites.

This is forcing us to really look deep into the various detection and remediation technologies to better understand how to prevent scenarios like the one described in this post.

This attack specifically is not something a signature would have ever picked up, it’s tightly integrated and dependent on what most would categorize as “good” code, and by good I mean it’s part of core and designed to do a good thing. Now extend this line of thinking, think beyond core.

If attackers are starting to look at how “good” code functions and finding ways to manipulate its use, what is to stop them from extending that thought process to code found in your templates, themes, extensions, plugins? This is a real problem that extends far beyond Joomla and will soon plague other CMS applications, if they are not already.

If you have something to add or share on the post, use the comments we’d love to get your hear from you.

If you find yourself in a similar situation, suffering repeated attacks or infections be sure to contact us. Whether you’re infected and need to be cleared, or prefer not to have to deal with this at all, we have a complete security solution to keep your website clean and safe.

PHP Backdoors: Hidden With Clever Use of Extract Function

When a site gets compromised, one thing we know for sure is that attackers love to leave malware that allows them access back to the site; this type of malware is called a backdoor. This type of malware was named this because it allows for remote control of a compromised website in a way that bypasses appropriate authentication methods. You can update your site, change passwords, along with any of your admin procedures, and the backdoor would still be there allowing unexpected access to an attacker.

Backdoors are also very hard to find because they don’t have to be linked in the site, they can be very small and be easily confused with “normal” code. Some of them have passwords, some are heavily encrypted/encoded and can be anywhere on your site, file system or database.

We have written extensively about website backdoors (generally in PHP) that allow for continuous reinfections and control of hacked websites.

You can read something more about backdoors on these links:


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Mysterious Zencart Redirects Leverage HTTP Headers

About a week ago we got an interesting Zencart case. Being that we don’t often write about Zencart we figured it’d be good time to share the case and details on what we found.

The Scenario

The site was redirecting to “www .promgirl .de”. I know, not very unique.

Additionally, it was only affecting “www” instances, all “non-www” instances were working correctly with no redirects. We also noticed that it would only trigger with specific User Agents and Referrers. This shouldn’t be new as we’ve talked at length about conditional malware.

Sucuri-Zencart-Analysis

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Many Pieces of a Puzzle: Target, Neiman Marcus and Website Hacking

Corporations get hacked all the time. This is not news to anyone in the security business, but it has certainly received a lot of attention from those in the media over the last few weeks because of a couple of large-scale credit card events at both Target and Neiman Marcus.

Website Malware

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