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ELFLoader

This is a ELF object in memory loader/runner. The goal is to create a single elf loader that can be used to run follow on capabilities across all x86_64 and x86 nix operating systems.

How it works

The way this loader works is that it has all the code needed to build and load an ELF object for the OS its been compiled for, anything that gets sent to it that isn't an elf file, isn't for the right arch, or if it links to something that can't be resolved it ends up exiting out without attempting to run.

Resolving Symbols

A key difference between the COFFLoader and this is that it uses the standard definitions from the OS's libc instead of having to redefine every function used.

Project Layout

.
├── includes
│   ├── beacon_api.h
│   ├── beacon_compatibility.h
│   ├── debug.h
│   ├── ELFLoader.h
│   └── minimal_elf.h
├── Makefile
├── README.md
├── SA
│   └── src
│       ├── cat.c
│       ├── chmod.c
│       ├── env.c
│       ├── find.c
│       ├── grep.c
│       ├── id.c
│       ├── ifconfig.c
│       ├── pwd.c
│       ├── tasklist.c
│       ├── uname.c
│       ├── walk.c
│       └── whoami.c
├── Scripts
│   └── beacon_generate.py
├── src
│   ├── beacon_compatibility.c
│   └── ELFLoader.c
└── testobjects
    ├── getuid.c
    ├── test2.c
    ├── test2_duplicatetext.c
    └── test.c

6 directories, 26 files

Examples

Example of find.o

Generate to cat the files found, replacement for find /etc/ -iname *release -exec cat {} \; or cat /etc/*release*

Beacon>reset
Beacon>addString /etc
Beacon>addString release
Beacon>addString
Beacon>addint 1
Beacon>addint 1
Beacon>addint 1
Beacon>generate
b'26000000050000002f657463000800000072656c65617365000100000000010000000100000001000000'

./ELFLoader.out ./SA/src/find.o 26000000050000002f657463000800000072656c65617365000100000000010000000100000001000000

Example of grep.o

Generate to list all files with rwx memory permissions in /proc.

Beacon>reset
Beacon>addString /proc
Beacon>addString rwx
Beacon>addString maps
Beacon>addint 1
Beacon>addint 0
Beacon>addint 0
Beacon>generate
b'27000000060000002f70726f63000400000072777800050000006d61707300010000000000000000000000'

./ELFLoader.out ./SA/src/grep.o 27000000060000002f70726f63000400000072777800050000006d61707300010000000000000000000000

Example of chmod

Generate the arguments for chmod 777 /tmp/test.sh.

Beacon>reset
Beacon>addString 777
Beacon>addString /tmp/test.sh
Beacon>generate
b'1900000004000000373737000d0000002f746d702f746573742e736800'

./ELFLoader.out ./SA/src/chmod.o 1900000004000000373737000d0000002f746d702f746573742e736800

Example of uname

This is the generic example that doesn't take any arguments.

./ELFLoader.out SA/src/uname.o

Runner and Library Example

make x86_64so
make x86_64runner
LD_LIBRARY_PATH=. ./runner.out ./SA/src/env.o