Find Malware in Image Files

Malware

It’s a nightmare. Your production environment was compromised and you actually don’t know how and how much data was stolen. For sure there are different ways to be compromised. In this post I just want to explain, how hackers can get full access to your production environment by using image files.

As explained on Snapfast and Sucuri it is pretty easy to store any kind of PHP code in EXIF headers. Often times it only needs a simple script to create an administrator account. If you are using third-party extensions with an image upload function or if you are late with the last security update, there is a high risk to be compromised.

You can use commands like svn status or git status to find changes, but this is no guarantee to find malicious code, because oftentimes your /media/ or similar folders are not version controlled.

Here is one simple command how you can find infected image files.

In case if any file is infected, you will see the following search result.

5 useful commands for your daily work with Magento

Daily Work

1. Backup your media/catalog

Create a manually backup of media/catalog without /cache/ folder

The same with the current date in the filename.

2. Files not owned by apache

Find files which are not owned by apache group or user. This is useful if you want detect possible permission issues.

3. SQL / CSV files in your document root

You should never left database dump or other export files with sensible information in your document root, because there is a potential risk that those files can be downloaded from outside, depending on your security settings. To make sure your production environment is save, just run a simple ” find ” with the option ” iregex “.

4. List report files created in the last 24 hours

Here are some more options you can use for ” -ctime “.

5. Truncate log files

A fast growing system.log or exception.log can be the cause of a server outage. If you want empty log files on a production environment, the command ” truncate ” will help you.

For further debugging you can keep log data by specifying the size.

Table is marked as crashed and should be repaired

Don’t freak out if your Magento is not working and because of the following error message.

The reason of a crashed MySQL table is mostly related to a server issue. For example:

  • Any kind of hard-disk failure
  • Sudden server reboot (power outage in hosting)
  • Hard server reboot (ACPI shutdown)

In most cases you can repair the affected table with a simple repair command, which comes with MySQL.

This command looks pretty easy and safe, but keep in mind that you should always create a backup before you change anything in your database, because probably more MySQL tables are affected.