In this series of posts, I’m looking at different aspects of the Linux Kernel, starting from less complicated areas, to understand Linux Kernel a little better. During this effort, I pay special attention to the security aspect and highlight areas that might be important for security research and testing. In this post, we look at the history, usage, internals and implementation details of procfs which is responsible for the /proc mount and sysfs which is responsible for /sys.
Colombo White Hat Security is a group focused on sharing security knowledge with Sri Lankan security enthusiasts and professionals. One objective of this group is to recognize and bring together the individuals interested in security domain and providing them more visibility within the community. This CTF is a part of such effort. The other intention of the CTF is to give an opportunity to do some hands-on hacking so that all the participants can learn at least few things out of it. For the first CTF, we had exactly 150 players. There were 20 flags hidden in the system. 62 players (41%) found over 50% of the flags. 40 players (26.5%) found over 85% of the flags. 24 players (16%) found all the flags!
This assembly program is designed to create a very simple game where user is allowed to guess a hard-coded number between 1 and 255. This hard-coded number can be replaced by a randomly generated number using a random number generator for EMU8086, which is bit complex because EMU8086 do not contain an instruction to do this implicitly. Program will output if guess is higher or lower than the input number. Since the code is well commented this program can be used to understand how 8086 CPU works and how to program it.