In this series of posts we dive into the internals of the Donex Ransomware. This series serves mostly as notes to keep track of my findings. I also record the entire analysis process and upload a series of videos on my YouTube channel. More info inside the post :)

In this post, I provide a detailed explanation of how to manually define the inverse ring homomorphism in SageMath, mapping a quotient ring over a finite field to a finite extension field of the same characteristic.

One of the first challenges I had solved, back in 2022. This one taught me about resultants, coppersmith’s small roots and how to work with curves defined over a ring instead of a finite field.

This was a challenge I enjoyed solving in LITCTF 2023. I considered it a good introduction to variable elimination techniques, such as Groebner Basis and resultants.

Hashing Frenzy was a cool challenge related to problem solving via lattice reduction techniques. My goal is to showcase some of the intuition required to translate linear equations to instances of lattice problems.