Microsoft, the NSA, and You, by Andrew Fernandes


Microsoft Installs US Spy Agency with Windows 

Research Triangle Park, NC - 31 August 1999 - Between Hotmail hacks and
browser bugs, Microsoft has a dismal track record in computer security.
Most of us accept these minor security flaws and go on with life. But
how is an IT manager to feel when they learn that in every copy of
Windows sold, Microsoft may have installed a 'back door' for the
National Security Agency (NSA - the USA's spy agency) making it orders
of magnitude easier for the US government to access their computers? 

While investigating the security subsystems of WindowsNT4, Cryptonym's
Chief Scientist Andrew Fernandes discovered exactly that - a back door
for the NSA in every copy of Win95/98/NT4 and Windows2000. Building on
the work of Nicko van Someren (NCipher), and Adi Shamir (the 'S' in
'RSA'), Andrew was investigating Microsoft's "CryptoAPI" architecture
for security flaws. Since the CryptoAPI is the fundamental building
block of cryptographic security in Windows, any flaw in it would open
Windows to electronic attack.

Normally, Windows components are stripped of identifying information. If the
computer is calculating "number_of_hours = 24 * number_of_days", the only
thing a human can understand is that the computer is multiplying "a = 24 * b".
Without the symbols "number_of_hours" and "number_of_days", we may have no
idea what 'a' and 'b' stand for, or even that they calculate units of time. 

In the CryptoAPI system, it was well known that Windows used special numbers
called "cryptographic public keys" to verify the integrity of a CryptoAPI
component before using that component's services. In other words, programmers
already knew that windows performed the calculation "component_validity =
crypto_verify(23479237498234...,crypto_component)", but no-one knew exactly
what the cryptographic key "23479237498234..." meant semantically. 

Then came WindowsNT4's Service Pack 5. In this service release of software
from Microsoft, the company crucially forgot to remove the symbolic
information identifying the security components. It turns out that there are
really two keys used by Windows; the first belongs to Microsoft, and it allows
them to securely load CryptoAPI services; the second belongs to the NSA. That
means that the NSA can also securely load CryptoAPI services... on your
machine, and without your authorization. 

The result is that it is tremendously easier for the NSA to load unauthorized
security services on all copies of Microsoft Windows, and once these security
services are loaded, they can effectively compromise your entire operating
system. For non-American IT managers relying on WinNT to operate highly secure
data centers, this find is worrying. The US government is currently making it
as difficult as possible for "strong" crypto to be used outside of the US;
that they have also installed a cryptographic back-door in the world's most
abundant operating system should send a strong message to foreign IT managers.

There is good news among the bad, however. It turns out that there is a flaw
in the way the "crypto_verify" function is implemented. Because of the way the
crypto verification occurs, users can easily eliminate or replace the NSA key
from the operating system without modifying any of Microsoft's original
components. Since the NSA key is easily replaced, it means that non-US
companies are free to install "strong" crypto services into Windows, without
Microsoft's or the NSA's approval. Thus the NSA has effectively removed export
control of "strong" crypto from Windows. A demonstration program that replaces
the NSA key can be found on Cryptonym's website. 

Cryptonym: Bringing you the Next Generation of Internet Security,
using cryptography, risk management, and public key infrastructure. 

Interview Contact:
   Andrew Fernandes
   Telephone: +1 919 469 4714
   email: andrew@AT@cryptonym.com
   Fax: +1 919 469 8708 

Cryptonym Corporation
1695 Lincolnshire Boulevard
Mississauga, Ontario
Canada  L5E 2T2 

http://www.cryptonym.com 

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