Vulnerable computer systems and applications:
The PHP/C99 shell is malware that is inserted into web servers in order to provide attackers full control of the server. It is inserted when security vulnerabilities are found and used in websites.
- Regularly backup your server data;
- Update Content Management Systems (Word Press, Joomla, etc.);
- Update extensions, and delete unused ones;
- Use strong passwords;
- Restrict access to files and directories;
- Regularly check web page vulnerabilities with free tools.