HHousen's writeups to various HackTheBox machines and challenges.
What is HackTheBox?
"Hack The Box is an online platform allowing you to test your penetration testing skills and exchange ideas and methodologies with thousands of people in the security field." - hackthebox.com
"Machines/Boxes are instances of vulnerable virtual machines. These are virtualized services, virtualized operating systems, and virtualized hardware. Boxes can host different Operating Systems; Linux, Windows, FreeBSD, and more."
"Challenges are bite-sized applications for different pentesting techniques." They are similar to traditional CTF-style tasks.