Elf

Linux ELF Runtime Crypter

6 minute read Published:

A Simple Linux ELF Runtime Crypter Using memfd_create Syscall
"Even for Elves, they were stealthy little twerps. They'd taken our measure before we'd even seen them." — Marshall Volnikov Last month I wrote a post about the memfd_create syscall and left some ideas in the end. Today I’m here to show an example of such ideas implemented in an ELF runtime crypter (kinda lame, I know but good for this demonstration). What is it? Glad you asked.

Running ELF executables from memory

7 minute read Published:

Executing ELF binary files from memory with memfd_create syscall
Something that always fascinated me was running code directly from memory. From Process Hollowing (aka RunPE) to PTRACE injection. I had some success playing around with it in C in the past, without using any of the previous mentioned methods, but unfortunately the code is lost somewhere in the forums of VXHeavens (sadly no longer online) but the code was buggy and worked only with Linux 32bit systems (I wish I knew about shm_open back then, which is sort of an alternative for the syscall we are using in this post, mainly targeting older systems where memfd_create is not available).

More fun with ELF files and GoLang - Code Caves

2 minute read Published:

Finding code caves in ELF binaries with GoLang
A code cave is a piece of code that is written to a process's memory by another program. The code can be executed by creating a remote thread within the target process. The Code cave of a code is often a reference to a section of the code’s script functions that have capacity for the injection of custom instructions. For example, if a script’s memory allows for 5 bytes and only 3 bytes are used, then the remaining 2 bytes can be used to add external code to the script.

Linux.Cephei: a Nim virus

3 minute read Published:

Simple prepender virus written in Nim
Nim is a systems and applications programming language. It has nice features such as producing dependency-free binaries, running on a huge list of operating systems and architectures and compiling to C, C++ or JavaScript. I’ve been messing with it for a while and I am very pleased with it. To be honest, Nim and Go have been my choices when I need to start a new project (goodbye Python, at least for now).

Having fun with ELF files and GoLang

2 minute read Published:

Opening ELF files with GoLang
Now I will show how GoLang interacts with ELF files in a generic example. You could look further into the native module here. I do recommend reading it, I am using some bits of code extracted directly from the module source. It is basically the same idea as the PE, similar module. You can extend it depending on your needs. Here you go. package main import ( "fmt" "io" "os" "debug/elf" ) func check(e error) { if e !

Linux.Liora: a Go virus

4 minute read Published:

Simple prepender virus written in GoLang
So this guy asks me in a job interview last week “Have you ever developed in Go?” and well what’s best to learn a language than writting a prepender (probably a lot of things but don’t kill my thrill)? There you have it, the probably first ever binary infector written in GoLang (SPTH LIP page “outdately” confirms that). Basically a port from my Linux.Zariche ‘cause my life is in a hurry.