The very first ransomware, more than 25 years ago, was the AIDS Information Trojan, that ran on old MS-DOS: a trojan horse that replaces the AUTOEXEC.BAT file which would be used to count the number of times the computer has booted.
Once this boot count reaches 90, AIDS hides directories and encrypts the names of all files on drive C: and asks the user to renew the license and contact PC Cyborg Corporation for payment (which would involve sending 189 US$ to a post office box in Panama).
Today, most file-scrambling ransomware is written for Windows computers, although it can encrypt files anywhere they have write access, including file servers and cloud storage sites.
There are also a few attempts at both Android and Linux ransomware.
Recently, a new generation on ransomware was discovered.
A ransomware written in PHP
From Naked Security:
…if a crook has your blog password and can upload files to your server, or if you have an unpatched server plugin that allows him to modify files that are supposed to be write-protected, and he can alter one or more of your PHP files… …then he can install a payload on your website that will trigger whenever anyone happens to visit the booby-trapped page.
The malware, known as Troj/PHPRansm-B, infects your server with a index.php file that contains:
- File encrypting and decrypting code using PHP.
- Style-sheet information using CSS, plus inline images.
Once the encryption process is completed, anyone visiting the page will see a warning page like this:
How can I prevent it?
Naked Security suggests:
- Pick a proper password for your web server, content management system or blog.
- Consider using two-factor authentication.
- Review all your server access permissions.
- Make sure your server is patched against security holes.
- Run a real-time anti-virus on your server.