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Message-ID: <4EBA7BEE.2020004@propergander.org.uk> Date: Wed, 09 Nov 2011 13:11:10 +0000 From: Dave <mrx@...pergander.org.uk> To: full-disclosure@...ts.grok.org.uk Subject: Re: Microsoft Windows vulnerability in TCP/IP Could Allow Remote Code Execution (2588516) -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 09/11/2011 11:45, Dan Rosenberg wrote: > On Wed, Nov 9, 2011 at 6:25 AM, Darren Martyn > <d.martyn.fulldisclosure@...il.com> wrote: >> Balls, I forgot to add this to the last message, but has anyone examined the >> patch yet? I can only imagine it would be VERY interesting to look at... >> <sarcasm> Or that it opens all UDP ports so that there are no closed ones to >> exploit </sarcasm> >> > > Yet another bug class (refcount overflows) that the PaX Team > eradicated years ago and everyone else is still scrambling to catch > up. > > People seem incredulous that the bug can be triggered by sending > traffic to closed ports. Keep in mind that the only way your > networking stack knows to reject packets that are directed towards > closed ports is to do some preliminary parsing of those packets, > namely allocating some control structures, receiving at least the > physical/link layer frame, IP header, and transport layer header, and > parsing out the port and destination address. There's plenty of > things that can go wrong before the kernel decides "this is for a port > that's not open" and drops it, which appears to be what happened here. > Doesn't make the bug any less terrible, but it's not quite as > surprising as people seem to think. Yes, I agree. The term "closed port" is somewhat misleading to those who have no idea of how a TCP/IP stack works. What is surprising though is that this flaw exists in such a mature OS as Windows. But then again this is Microsoft we are talking about. >> On Wed, Nov 9, 2011 at 11:22 AM, Darren Martyn >> <d.martyn.fulldisclosure@...il.com> wrote: >>> >>> So... Another Conficker type worm possible from this bug if everyone cocks >>> up and fails to patch? >>> > > While I'd love to see an exploit from a purely academic perspective, > it doesn't appear that this is the type of bug where exploitation is > going to be reliable enough to support a worm. The reference counter > in question is most likely 32 bits, but even giving the benefit of the > doubt and saying it's a 16-bit refcount, that's still 2^16 events > (probably receiving a certain UDP packet) that need to be triggered > precisely in order to cause a refcount overflow and then trigger a > remote kernel use-after-free condition, which wouldn't be trivial to > exploit even by itself. On an unreliable network like the Internet, > it seems unlikely that the kind of traffic volume required to trigger > this bug could be generated without dropping a single packet. > Reliable DoS seems more likely though. > > -Dan > >>> On Tue, Nov 8, 2011 at 10:10 PM, Nahuel Grisolia >>> <nahuel.grisolia@...il.com> wrote: >>>> >>>> Kingcope, where's the exploit? >>>> >>>> :P >>>> >>>> On Nov 8, 2011, at 6:53 PM, Henri Salo wrote: >>>> >>>>> http://technet.microsoft.com/en-us/security/bulletin/ms11-083 >>>>> >>>>> "The vulnerability could allow remote code execution if an attacker >>>>> sends a continuous flow of specially crafted UDP packets to a closed port on >>>>> a target system." >>>>> >>>>> Microsoft did it once again. >>>>> >>>>> - Henri Salo >>>>> >>>>> _______________________________________________ >>>>> Full-Disclosure - We believe in it. >>>>> Charter: http://lists.grok.org.uk/full-disclosure-charter.html >>>>> Hosted and sponsored by Secunia - http://secunia.com/ >>>> >>>> _______________________________________________ >>>> Full-Disclosure - We believe in it. >>>> Charter: http://lists.grok.org.uk/full-disclosure-charter.html >>>> Hosted and sponsored by Secunia - http://secunia.com/ >>> >>> >>> >>> -- >>> My Homepage :D >>> >> >> >> >> -- >> My Homepage :D >> >> >> _______________________________________________ >> Full-Disclosure - We believe in it. >> Charter: http://lists.grok.org.uk/full-disclosure-charter.html >> Hosted and sponsored by Secunia - http://secunia.com/ >> > > _______________________________________________ > Full-Disclosure - We believe in it. > Charter: http://lists.grok.org.uk/full-disclosure-charter.html > Hosted and sponsored by Secunia - http://secunia.com/ > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.2 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQEVAwUBTrp77rIvn8UFHWSmAQLAoAf/SQFShTXjNjfclb73hs4z/RajsNJfzl5x PIdT7N5q57Uzem1c7rvRoIPwF/Uv3wyL5qpyjq7USO4X/VhswlXgjVM022NPkCRE uRV5/rES2lvBM7CVpJo/virO9qoKOs4VGzZK1GNbGyiE4PeCvzFZvyrtGHyEALc9 rDX00ZCo31O1xVP9M6X7g0il82x5LcDGpNQ5GZRFhpwfEkJeIZOIb80j90Y17Gu2 3fSFmFIHQRWT2vx3gEEi6PgI3rquQWKgS2RMLdBGigTJX5Sq2vD9RjT26enpRl4V NO9BEBVm9/zdebCQ4ahfPrv+M9IZGxak6sQ+SB+mMaoukSFz8cqWsA== =VEn4 -----END PGP SIGNATURE----- _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/
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