WebHostUK Blog

Hello,

Recently we our operation team found that accounts that are running Joomla and WordPress applications are being hacked. Most start with an automated scanner tool that scans for specific versions of Joomla and specific extensions versions. (Same with wordpress and others) Once vulnerabilities are identified then one of the below is used to gain access.

Here’s the main cause of it:

The _MACOSX folder is automatically generated when files are zipped on an Apple computer. Because the use of Mac you will find them after unzipping your downloaded Zip-archive on a Windows PC. Simply forget about this folder. You don´t need it.

Whats with __MACOSX in Zip files?

Recently people are using Mac’s for development these days. Most core developers from some of the leading web frameworks use Mac as their primary development platform. Several plugin and theme authors for WordPress also develop on Mac. This is good thing but also has side effects of this development.

The easiest way to archive something on Mac is to right click on directory of choice in Finder and select “Archive as…”. This creates a Zip file, which then the developer can distribute to users. After this procedure another folder suspiciously named”%%__MACOSX%%” gets created at the root of Zip archive. Bellow is an example:

==================================================================

/funvilla/wp-content/oqey_gallery/skins/__MACOSX

/images/stories/Halloween/__MACOSX

/wp-content/plugins/uBillboard/__MACOSX

/public_html/tmp/install_4a5e043578f85/__MACOSX

==================================================================

This folder contains other things, thumbnail for images in the original archive. These kind of unwanted undesirable things are really not necessary. It’s okay, try to keep cool. Bellow we are presenting a systematic analysis of what Mac OSX does is wrong, stupid and unnecessary:

In WordPress themes directory, if each theme starts creating its own”%%__MACOSX%%” folder, then themes directory would soon get crowded with useless garbage. This, creating an entire tree structure in the archive just breaks things in more ways. Example: each WordPress theme starts creating”%%__MACOSX%%” folders in the root of the archive. As a result the new theme will also try to extract in the”%%__MACOSX%%” folder. Not only this, some programs like Gallery ( Joomla ) also have the ability to load plugins/images directly from Zip files. Hence, people end up with unwanted images, themes and plugins in setup. This might just break the installation. Again, one did not explicitly create that folder. If someone creates a virus, that just modifies the default zip program on Mac to sneak in malicious payload via the”%%__MACOSX%%” folders in any new Zip archives, it’s a security risk.

This way we encountered that all the data inside”%%__MACOSX%%” folder is created from directory itself. No external information is used / needed. Think why anyone would ever need such new folder. The zip file has been produced on a system running Mac OSX, they’re irrelevant files (mac filesystem metadata) one can just delete the directory.

Next, we also encountered the Vulnerability Found in timthumb.php

We found a vulnerability in a popular image resizing library called TimThumb, used in many WordPress and Joomla themes and plugins. This allows one ( HACKER ) to upload and execute despotic PHP code in the TimThumb cache directory. Once, PHP code is uploaded and executed, any site can be compromised as per the HACKER.
We strongly recommend deleting timthumb.php / thumb.php / createthumb.php / showthumb.php / class.img2thumb.php / action.changethumb.php like file from the account. If the file exists in a theme or plugin that you’re no longer using you may want to remove the entire theme or plugin directory.
Still, one wish to use the TimThumb, then make sure to update the file the latest version and remember to check the TimThumb site regularly for updates. One should also set ALLOW_EXTERNAL to false and find the $allowedSites array inside the file and remove the domain names to prevent remote file downloading.

Please make sure it is as follows:

define( ‘ALLOW_EXTERNAL’, false );

Then make changes as following:

$allowedSites = array (

        'flickr.com',

        'picasa.com',

        'img.youtube.com',

        'upload.wikimedia.org',

);

Change it to look like bellow:

$allowedSites = array();

Always be sure to use the built-in WordPress functions for Themes and Plugins such as: add_image_size to resize images.

Kind Regards,
Daniel Smith
Level II Support Department
http://www.WebHost.Uk.Net
http://www.WebHosting.Uk.Net
Support Portal: https://secure.webhost.uk.net

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