bugtraq - [VulnDiscuss] RE: MacOSX - crash screensaver locked with password and get thedesktop back

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Date: Mon, 7 Jul 2003 16:10:28 -0500
From: "Tim Yardley" <liquid@...eheart.com>
To: "'Delfim Machado'" <bipbip@...o.org>,
	<bugtraq@...urityfocus.com>,
	<full-disclosure@...ts.netsys.com>,
	<product-security@...le.com>,
	<vulnwatch@...nwatch.org>,
	<vuln@...urity.nnov.ru>,
	<bugs@...uritytracker.com>
Subject: [VulnDiscuss] RE: MacOSX - crash screensaver locked with password and get thedesktop back

>From console:
2003-07-07 15:59:40.973 ScreenSaverEngine[6247] Exception raised during
posting of notification.  Ignored.  exception: *** -[NSCFArray
objectAtIndex:]: index (0) beyond bounds (0)

corresponding crashlog:
Date/Time:  2003-07-07 15:59:38 -0500
OS Version: 10.2.6 (Build 6L60)
Host:       liquid

Command:    ScreenSaverEngine
PID:        6244

Exception:  EXC_BAD_ACCESS (0x0001)
Codes:      KERN_INVALID_ADDRESS (0x0001) at 0x822ae308

Thread 0 Crashed:
 #0   0x9068ba64 in objc_msgSend
 #1   0x97df221c in NSPopAutoreleasePool
 #2   0x930b1dd0 in -[NSApplication run]
 #3   0x00004678 in 0x4678
 #4   0x00004328 in 0x4328
 #5   0x000041a8 in 0x41a8

Thread 1:
 #0   0x90073c28 in mach_msg_trap
 #1   0x90005f70 in mach_msg
 #2   0xc0007758 in __ape_internal
 #3   0xc0001160 in __ape_agent
 #4   0x90020d28 in _pthread_body

Thread 2:
 #0   0x90073c28 in mach_msg_trap
 #1   0x90005f70 in mach_msg
 #2   0x901489f0 in __CFRunLoopRun
 #3   0x90180f58 in CFRunLoopRunSpecific
 #4   0x90148240 in CFRunLoopRun
 #5   0x022000cc in thread_main
 #6   0x90020d28 in _pthread_body

Thread 3:
 #0   0x90014d08 in syscall_thread_switch
 #1   0x97e03ef4 in +[NSThread sleepUntilDate:]
 #2   0x93081cac in -[NSUIHeartBeat _heartBeatThread:]
 #3   0x97e2cc50 in forkThreadForFunction
 #4   0x90020d28 in _pthread_body

PPC Thread State:
  srr0: 0x9068ba64 srr1: 0x0000f030                vrsave: 0x00000000
   xer: 0x20000000   lr: 0x97df221c  ctr: 0x9068ba3c   mq: 0x00000000
    r0: 0x97df221c   r1: 0xbffff440   r2: 0x24000280   r3: 0x025a2d80
    r4: 0x906ca0d0   r5: 0x00000000   r6: 0x00000000   r7: 0x02236f50
    r8: 0x0004d010   r9: 0x02266288  r10: 0x0004d290  r11: 0x85858584
   r12: 0x80048080  r13: 0x00000000  r14: 0x00000000  r15: 0x00000000
   r16: 0x00000000  r17: 0x00000000  r18: 0x00000000  r19: 0x00000000
   r20: 0x00000000  r21: 0x00000000  r22: 0x00000000  r23: 0x00000000
   r24: 0x00000000  r25: 0x00000000  r26: 0xbffffdf4  r27: 0x00000031
   r28: 0x00000005  r29: 0x025a2d80  r30: 0x00081460  r31: 0x97df20c0

-----Original Message-----
From: Delfim Machado [mailto:bipbip@...o.org] 
Sent: Friday, July 04, 2003 9:23 AM
To: bugtraq@...urityfocus.com; full-disclosure@...ts.netsys.com;
product-security@...le.com; vulnwatch@...nwatch.org; vuln@...urity.nnov.ru;
bugs@...uritytracker.com
Cc: phiber@...bernet.org
Subject: [VulnWatch] MacOSX - crash screensaver locked with password and get
thedesktop back

Hi all,

three days ago i discovered a security issue, with the last MacOSX. 

there is a way to crash the screensaver locked with password and gain
the desktop.

how? - you ask.
i don't know the exact amount of characters, only that if you leave a
key pressed for 5 minutes or more and then hit the enter key, you crash
the screensaver and gain access to the desktop.
you can mess the desktop and all around it (network, mail, docs,
anything you can imagine).

i think that this is a huge secure hole and it must be corrected.

i hope that this is good for everyone who cares about "how to secure
your desktop".

solution?
wait until someone at the apple make a patch and realise it...

here is the mail that i've sent to apple security people,  they didn't
replied :(

-- BEGIN APPLE MESSAGE --
                               To: 
product-security@...le.com
                          Subject: 
[BUG] forgot your screensaver
password ?? Hackit anyway
Hi all

(tested machines at the bottom of this message)

sorry about the subject, but there is a problem with the auth prompt
when you have the screensaver running.

i do not know the exact amount of characters to make the auth prompt
blow up, but here is what i do:

with the screensaver runnig, leave  something at the top of the keyboard
and leave it there for 5 or more minutes, then hit ENTER.
The screensaver dies and you have your desktop open to anyone.

desktop open, network open, hackers go away :)

i'll wait for an answer until 3 of Jully and then send this problem to
full-disclosure@...ts.netsys.com and bugtraq@...urityfocus.com

if you need more time, please tell me that i'll wait until the patch be
ready to deploy.

OS tested:  didn't get a mac not updated ... (uname -a)
(Powerbook)
Darwin roadrunner 6.6 Darwin Kernel Version 6.6: Thu May  1 21:48:54 PDT
2003; root:xnu/xnu-344.34.obj~1/RELEASE_PPC  Power Macintosh powerpc
(iMac)
Darwin MacLulo 6.6 Darwin Kernel Version 6.6: Thu May  1 21:48:54 PDT
2003; root:xnu/xnu-344.34.obj~1/RELEASE_PPC  Power Macintosh powerpc
(Powerbook)
Darwin Proenca-Powerbook17 6.6 Darwin Kernel Version 6.6: Thu May  1
21:48:54 PDT 2003; root:xnu/xnu-344.34.obj~1/RELEASE_PPC  Power
Macintosh powerpc

PS: MacOSX r0x, keep on the good way!

-- END APPLE MESSAGE --

Cheers
--
Delfim Machado - dbcm@...o.org
XPTO:: Portuguese OpenSource Community - http://lab.xpto.org