Once you have completed the first three phases, you can move into the system hacking phase. You will recognize that tings are getting much more complex and that the system hacking phase cannot be completed in a single pass. It involves a methodical approach that includes cracking passwords, escalating privileges, executing applications, hiding files, covering tracks, concealing evidence, and then pushing into a complex attack.

This was written from CEHv8 material but the process applies to the process and concepts for most any CEH version.