Security

I finally started using Molly to send and receive messages via Signal. Molly is a hardened fork of Signal for Android, offering features such as an encrypted message database, automatic locking, shredding no longer needed secrets from RAM, notifications via UnifiedPush, and Tor / SOCKS proxy support. This is by no means an alternative to Signal itself, but rather an alternative (and hardened) Android client for Signal. While these extra security features are great, my main motivation to use Molly was battery saving, actually. I’m on GrapheneOS, which does offer sandboxed Google Play (opt-in), yet I’ve chosen not to use it. This means I’m not using Google’s Firebase Cloud Messaging (FCM) for notifications either, which Signal by default heavily relies on. However, it continues to make me very glad I can still use a secure and open source mobile operating system (GrapheneOS) in 2025, without needing to rely on proprietary and privacy-impairing functionality. ...

OpenWrt is an open source Linux project aimed at embedded devices to route network traffic (e.g. routers). I’ve consistently run OpenWrt on my home routers for over a decade now (I still remember the brief LEDE split), and it has since been my preferred home router OS. While I’ve also wanted to experiment with OPNsense (and pfSense before), I’ve never had a real reason to thus far, but I digress…​ It might be interesting to add some network security such as intrusion prevention to your residential gateway directly. You might of old be familiar with Fail2Ban, and I’ve happily used Fail2Ban for years. CrowdSec is a similar solution, albeit more community-driven. Klaus Agnoletti, then (still?) head of community at CrowdSec, summarised the similarities and differences between the two: ...

Some time ago I documented how I configured WireGuard on my OpenWrt router at home, to connect securely to my home network (and the Internet, really) from wherever I am. I feel safer connecting to public Wi-Fi this way, also abroad when it allows me to save extra roaming costs. However, during my travels I sometimes come across networks which seem to block VPN connections, sometimes including my own personal WireGuard tunnel. For such cases I managed to tunnel my WireGuard connection over HTTPS, which is typically (far) less often blocked. ...

My previous post discussed the introduction of a Module-Lattice Key Encapsulation Mechanism (ML-KEM) post-quantum key exchange algorithm implementation in OpenSSH, and how to specify it in your SSH configurations. ML-KEM is the new FIPS 203 standard, previously known as Kyber, which was standardized by NIST on 2024-08-13. OpenSSH’s implementation of ML-KEM is a PQ/T hybrid approach that combines the post-quantum ML-KEM with the traditional X25519 key exchange algorithm. This post will cover the ML-KEM implementation in Caddy, the popular web server and reverse proxy. ...

OpenSSH 9.9, released on 2024-09-19, first introduced support for the new FIPS 203 Module-Lattice Key Encapsulation Mechanism (ML-KEM) post-quantum key exchange algorithm, previously known as Kyber. ML-KEM was formally standardized by NIST on 2024-08-13, and is designed to be secure against quantum attacks, making it a suitable choice for future-proofing cryptographic systems. The OpenSSH implementation of supporting ML-KEM, specifically the mlkem768x25519-sha256 key exchange algorithm, is a hybrid approach that combines the post-quantum ML-KEM with the standard X25519 key exchange algorithm. The benefit of a hybrid approach is that in the event that, after further cryptanalysis, the ML-KEM algorithm ends up being broken, the X25519 key exchange algorithm will still provide a secure fallback. At least for now, while we don’t yet have a Cryptographically Relevant Quantum Computer (CRQC) that can break X25519. There is currently an IETF draft for Post-Quantum Traditional (PQ/T) hybrid key exchange methods based on ML-KEM and Elliptic Curve Diffie-Hellman (ECDH) algorithms (also including X25519) for use in SSH. OpenSSH’s mlkem768x25519-sha256 key exchange is exactly such an example thereof, and is being described there. ...

I finally got hashcat running on Docker, with GPU support for NVIDIA cards. First, I needed to install Docker and NVIDIA Container Toolkit on my system, and add my user to the docker group. root $ pacman -S --needed docker nvidia-container-toolkit root $ systemctl enable --now docker.service root $ usermod -aG docker user Then I created a Dockerfile to set up the hashcat environment with NVIDIA support (using a BlackArch image): FROM blackarchlinux/blackarch:latest RUN pacman -Syu --noconfirm && \ pacman -S --noconfirm \ blackarch/cracken \ blackarch/pack \ blackarch/pipal \ extra/hashcat \ extra/hashcat-utils RUN mkdir -p /etc/OpenCL/vendors && \ echo "libnvidia-opencl.so.1" > /etc/OpenCL/vendors/nvidia.icd RUN mkdir /cracking...

These are some scribbles if I ever need to look up how to exploit Kerberoasting or AS-REP Roasting. I might expand on this later…​ ℹ️ This is nothing new, most of this stuff can be easily found on the Internet. This is just for my own reference. Please excuse my brevity. Environment For this article, we’re assuming the following (YMMV): user $ echo $SHELL /usr/bin/fish user $ which GetUserSPNs.py /usr/bin/GetUserSPNs.py user $ which GetNPUsers.py /usr/bin/GetNPUsers.py user $ set win_domain company.org user $ set dc_ip 192.168.1.1 user $ set regular_ad_user gijsbert...

These are some scribbles if I ever need to look up how to exploit AD CS misconfigurations, such as ESC1. I might expand on this later…​ ℹ️ This is nothing new, most of this stuff can be easily found on the Internet. This is just for my own reference. Please excuse my brevity. Environment For this article, we’re assuming the following (YMMV): user $ echo $SHELL /usr/bin/fish user $ which certipy /usr/bin/certipy user $ which dasel /usr/bin/dasel user $ set win_domain company.org user $ set dc_fqdn dc.{$win_domain} user $ set dc_ip 192.168.1.1 user $ set ca_fqdn ca.{$win_domain} user $ set ca_ip 192.168.1.10 user $ set ca_name COMPANYCA user $ set esc1_template_name ESC1Template user $ set regular_ad_user gijsbert user $ set domain_admin dawilbert user $ set domain_admin_upn {$domain_admin}@{$win_domain}...

I’ve been using Hashcat since I’ve been pentesting at my previous jobs, but I haven’t had the need to use it for a couple of years now. Recently I had another use case for it but I still don’t need to use nearly as often as I once did. I therefore decided to document some of this to easily look things up in the future. Extracting All Hashes from Active Directory To copy all hashes from Active Directory, you need domain administrator credentials. Once acquired, make a copy like so: ...

This post briefly describes how to configure an OpenWrt router to function as a WireGuard VPN server. This enables me to have my phone always be securely connected to my home router, from wherever I am. This is what it roughly looks like: First, install the necessary WireGuard kernel module: root # opkg update root # opkg install kmod-wiregard Generate a new private and public key pair for the server, and your first peer (e.g. your phone), and a pre-shared key for added post-quantum secrecy: ...