Website Malware Removal – WordPress Tips & Tricks
By Tony Perez on July 19, 2012 . 4 Comments
We often write posts that give you advice and recommendations around how to harden your websites, and have only recently begun to give advice on ways to navigate your backend and remove infections via terminal. But what about all the basics?
That’s what I want to cover in this post. All those things that you should know when trying to remove web malware from your site. Alternatively, if you’re already hacked, you can enlist our help to clean your website regardless of CMS.
Cleaning Basics
When working to clean your site there are a number of things you should know, I’ll wrap it into 4 key things:
Use Live ScannersDefault WP File StructureFile PermissionsDisabling Plugins
1. Use Live Scanners
Contrary to popular belief, utilizing web-based scanners are a necessity in this day and age. False positives are an acceptable risk in today’s fight against web-malware, they are much better than false-negatives. In other words, missing a possible infection.
So of course, there aren’t many live scanners out there on the market, none that are truly free and willingly give you a report without asking for a registration or payment of some kind:
Disclaimer: The scanner is not 100%, no AV type product should ever boast 100% certainty as it’s not possible in this domain. If it were, there wouldn’t be any competitors or service providers.
2. Default WP File Structure
What most don’t understand is how WordPress is organized by default, it’s an important distinction to make. In every install, there are core directories and files.
This is what a clean install looks like:
One option you have is to do your own integrity checkS by comparing your base install to the core install. As you might imagine, there is a way to do this via terminal, here is an example:
$ diff -r /Documents/WordPress/wp-includes /public_html/happysite.com/wp-includes
Why important?
It’s important because in more cases than most folks realize, you’ll want to replace your core install.
The reasoning is simple, from what we see, in a lot of infections once access is gained to the environment, backdoor payloads are pushed into the install directories. This allows the crackers to gain access to your environment directly. If you don’t have the ability to effectively scan every directory for known or new backdoors, then it’s good practice to replace the two core directorieswp-admin and wp-includes.
Please note the emphasis on replace, not update. This is important because an update will simply overwrite the existing files, to replace the backdoor in a file, it will not purge the directory. This means if a backdoor resides in a non-root file the update won’t clear the issue.
Hint: SEO Spam is notorious for doing this.
3. File Permissions
The ever important file permissions. The WordPress.org Codex offers some very good advice on specific permissions for WordPress installs. You can find a good article on the Codex: Changing File Permissions
The biggest take-away is simple:
Directories: 755Files: 644
There is a simple way to apply the changes via terminal:
Directories:
find [path to install] -type d -exec chmod 755 {} ;Files:
Find [path to install] -type f -exec chmod 644 {} ;
But what about the non-terminal types?
No problem. Using your favorite FTP client you should be able to do it easily. In this instance I’ll show you in FileZilla. While I wouldn’t save the credentials in the client, I’d recommend this client for most trying to work in FTP.
What I particularly like about it is you can use this client across the three most common platforms (e.g., MAC, Windows, Linux)
To change the permissions for all directories it’s easy, simply log into your server and click on the directory for your web-files, it can be: www, publich_html, htdocs, httpdocs, etc…
Once at the directory, right-click and click onproperties.
On the next screen you can type in 755 where it says Numeric value.
Be sure to also click Recurse into subdirectories and select Apply to directories only.
This will apply the 755 permission to all directories within the web directory
The good news is that the file permissions are just as easy. Simply follow the same steps as above, this time though you’ll type644 and select Apply to files only.
As you can see, there is no real secret here. Simply follow the recommendations you are given.
Another important note to make is that in Filezilla you can easily see the permission of your directories and files by looking to the far right of the directory or file, see below:
4. Disable Plugins
Here is another good tip. When using a scanner, if you continue to struggle identifying the location of the infection, one very common place to look in is the plugins directory.
What most people don’t realize is that you have the option to disable the plugins directory. Don’t be fooled by the use of “disable”, it simply means you can’t use the plugins. One very easy way to do this is rename the directory:
Example: plugins – > plugins.backup
This will kill all your plugins rendering them useless to your website. The point of doing this is to see if the infection is tied to the plugins. If it is, you’ll see that the live scanners will show clean when you rescan. If this is the case, another very good trick is to narrow down the infection further by disabling one plugin at a time.
Yes, this works and it’s very easy to do for novices.
Note: No, renaming is not going to hurt your site. When you remove the name and reset to its default the site will be fully functional again.
If you disable plugins and the infection is still present then you know it’s one of the following: core files, themes files, or database. If you followed the steps in section 2 then you know it’s in either the themes or the database.
This post is not meant to be a technical overview of how to remove website malware, instead it’s meant to help you diagnose the location of infections which in turn help you locate and remove the infection. It’s fundamentally a different approach, but it’s intended to be so. Believe it or not, the most novice of users would be able to use these techniques to quickly narrow down infections.
If you have any questions please contact us at info@sucuri.net.
filed under: learn
About Tony Perez
Tony works at Sucuri. His passion lies in educating and bringing awareness about online threats to business owners. He spends his time giving presentations and writing content that everyday website owners can appreciate. His passions revolve around understanding the psychology of bad actors, the impacts and havoc hacks have on website owners, and thinking through the evolution of attacks. You can find his personal thoughts on security at Tony on Security and you can follow him on Twitter at @perezbox.
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