Category Archives: Security

Smart Contracts and Cybersecurity

I was one of those people that used to think and say that blockchain, and the different technologies around it, are solutions for problems that don’t exist. That many people talk about it without knowing any technical details or implications, or focusing on the wrong topics (e.g. politics, finance, etc.) didn’t help either.

However, lately, I have been changing my mind. I’m just starting to explore the technology, but I already think that it is very interesting, new, and that it has much more meat that I thought. I guess I was suffering the Dunning-Kruger effect: when I didn’t know too much about it, I was more sure about my thoughts. Now I have many questions.

Continue reading

Containers: Rootful, Rootless, Privileged and Super Privileged

This article is about containers, the different types (depending on what privileges we let them have), and how they build their isolation: mainly kernel namespaces and capabilities, overlay filesystems, seccomp, and SELinux. My motivation to start this article was for me to understand a bit better how the combination of container isolation mechanisms and privileges affects (increasing or decreasing) the risk of kernel flaws.

Continue reading

My introduction to Z3 and solving satisfiability problems

Z3 is a powerful framework for problem solving, developed by Microsoft Research. Given a list of restrictions and conditions, Z3 finds one solution that satisfies them all, if that solution exists. Some complex problems can be solved easily with Z3. It can be used for multiple purposes but some known uses in security are exploiting or checking firewall rules. It is also a handy tool for solving many CTF challenges related to encryption and keygen generation.

Continue reading

Introduction to Landlock

Note: I published this post in a previous blog i closed. Now I’m re-publishing it here.

Landlock is yet another sandoxing mechanism for Linux, but with important differences. Its goal is to make possible to restrict access rights to different Linux elements (e.g. filesystem access), in a secure and programmatic way, without the need of admin privileges.

Continue reading

Introduction to dependencyCheck: an open source Software Composition Analysis (SCA) tool

depencencyCheck is an open source dependency security scanner. This kind of tools are also called SCA (Software Composition Analysis).

dependencyCheck identifies which dependencies (aka third party libraries) a software is using and indicates if any of them have known vulnerabilities.

Continue reading