This is part two of two talking about an out-of-order CPU I built. In this write-up, I will discuss the implementation of program loading, speculative memory-mapped I/O, branch prediction, and the ...

In this write-up, I will go through many weeks of development of an out-of-order CPU core. I will talk about lessons learned, explain microarchitecture concepts, and illustrate justifications (and ...

Overview The challenge itself is pretty small: #!/usr/bin/python3 from capstone import * from capstone.x86 import X86Op, X86_OP_IMM import os ALLOWED_MNEMONICS = ["jmp", "add", "mov", "sub", "inc...

In this writeup I analyze a riscv64 kernel that contains a VM and a process executed in userland. This process utilizes invalid reads/writes in order to trigger the VM. I construct a disassembler a...

Better Packet Filter is an arm64 kernel module that runs a custom VM with a user-supplied program to filter “packets” that are placed in a file. In this writeup, I analyze the VM and construct a pr...

This challenge requires a sequence of instructions that produces a target output. Initial Analysis This is an x86-64 ELF coded in C++. The main function contains a loop that prints the flag once...

This is a Golang LSP server that we have to reverse engineer in order to find commands that allow us to read the flag. Due to protections the flag can not be directly read, but a race condition can...

This challenge is a classic VM with an anti-debug feature. In this writeup I manually disassemble bytecode and analyze it. Initial Overview VM exe coded in C, takes an arg which is a 32 bit inte...

Gateway is a binary with complex obfuscation, including Heaven’s Gate for Linux. Real analysis is avoided by utilizing a side channel. Initial Analysis C (most likely), 32 bit, elf, no known pac...

This challenge is a simple return to stack challenge with ASLR but no PIE. The input size is very restrictive, so a relative jump is required to jump to a larger user controlled buffer. Initial ...