asm.sh

This is a zero-dependency framework for embedding (somewhat) portable inline assembly directly inside bash.

At a basic level, it works by spraying shellcode inside /proc/$$/mem. From there, you can do things that you normally can't. Here are a few examples:

Print "hello"

run_shellcode "48b801010101010101015048b869646d6d6e0b0101483104244889e66a015f6a065a6a01580f05"

Run inline assembly (intel)

__asm <<EOF
pop rdi
pop rsi
pop rbp
pop rbx
pop rbx
pop rdx
pop rcx
pop rax
xor rsp, rsp
jmp rsp
EOF

Run inline C

__c <<EOF
int main(){
    write(1,"test\n",5);
}
EOF

Using mkpage, you can pass data from C directly to bash variables

Note: inline asm and inline C require pwntools asm and ragg2/clang to be installed, respectively. The asmpp preprocessor is provided to have those dependencies not required at runtime

Run any linux system call

malloc 5 "$(echo "test" | xxd -p)"
syscall $__NR_write $STDOUT_FILENO $ptr 5

In all these examples, the injected code runs as the main process, meaning you can do things much faster and access the shell's memory directly. It also means your entire shell will crash if you mess up

Installation

git clone https://github.com/CoolElectronics/asm.sh
cd asm.sh
make install

Usage

Once installed, in any shell you can run source asm.sh. Make sure to run asm_init before running any commands.

Alternatively, you can grab the entire asm.sh from releases and include it inside your bash script if you don't want to manage dependencies.

Only amd64 is supported currently. ksh is supported but can be buggy sometimes. It may segfault instantly on your machine, i'm not entirely sure why