When a site gets hacked, the attack doesn’t end with the malicious payload or spam content. Hackers know that most website administrators will clean up the infection and look no further. Many go on to patch vulnerable software, change their passwords, and perform other post-hack steps. All of this is good, but hackers who follow through the sustainment phase of the attack also leave behind ways to easily reinfect the site.
After breaking into a website, hackers want to make sure they still have access if the original security hole is closed.