https://blog.mirch.io/tags/persistence/ Recent content in persistence on Rich Mirch Hugo en-us Wed, 09 Jan 2019 18:16:32 +0000 https://blog.mirch.io/2019/01/09/linux-persistence-idea-using-group-passwords/ Wed, 09 Jan 2019 18:16:32 +0000 https://blog.mirch.io/2019/01/09/linux-persistence-idea-using-group-passwords/ A rarely used feature on Linux and UNIX systems is the ability to add a password to a group. The concept is similar to how users are handled. An encrypted hash is stored in the second field of the <a href="http://man7.org/linux/man-pages/man5/gshadow.5.html">gshadow(5)</a> file. Anyone with the password can execute the <a href="http://man7.org/linux/man-pages/man1/newgrp.1.html">newgrp(1)</a> command to temporarily change their GID without having to be a member of the group. The goal of this post is to show how this feature can be leveraged to create persistence on a server in a semi stealthy way.