How NSA Access Was...
Built into Windows
by Duncan Campbell
April 09, 1999
Careless mistake reveals
subversion of Windows by NSA.
A CARELESS mistake by
Microsoft programmers has revealed that special
access codes prepared by the US National Security
Agency have been secretly built into Windows.
The NSA access
system is built into every version of the Windows
operating system now in use, except early releases
of Windows 95 (and its predecessors).
The discovery comes close on the heels of
the revelations earlier this year that another US software giant, Lotus,
had built an NSA "help information"
into its Notes system, and that security functions on other
software systems had been deliberately crippled.
The first discovery of the new NSA access system was made two years ago
by British researcher Dr Nicko van Someren. But it was only a few
weeks ago when a second researcher rediscovered the access system. With
it, he found the evidence linking it to NSA.
Computer security specialists have been aware for two years that unusual
features are contained inside a standard Windows software "driver" used
for security and encryption functions. The driver, called ADVAPI.DLL,
enables and controls a range of security functions.
If you use Windows, you will find it in the
C:\Windows\system directory of your computer.
ADVAPI.DLL works closely with Microsoft Internet Explorer, but will only
run cryptographic functions that the US governments allows Microsoft to
export. That information is bad enough news, from a European point of
view. Now, it turns out that ADVAPI will run special programs inserted
and controlled by NSA. As yet, no-one knows what these programs are, or
what they do.
Dr Nicko van Someren reported at last year's Crypto 98 conference that
he had disassembled the ADVADPI driver. He found it contained two
different keys. One was used by Microsoft to control the cryptographic
functions enabled in Windows, in compliance with US export regulations.
But the reason for building in a second key,
or who owned it, remained a mystery.
A second key
Two weeks ago, a US security
company came up with conclusive evidence that the second key belongs to
Like Dr van Someren, Andrew Fernandez,
chief scientist with Cryptonym of Morrisville, North Carolina, had been
probing the presence and significance of the two keys.
Then he checked
the latest Service Pack release for
Windows NT4, Service Pack 5.
He found that Microsoft's developers had
failed to remove or "strip" the debugging symbols used to test this
software before they released it. Inside the code were the labels for
the two keys.
Fernandez reported his re-discovery of the two CAPI keys, and their
secret meaning, to "Advances in Cryptology, Crypto'99" conference held
in Santa Barbara.
According to those present at the conference, Windows
developers attending the conference did not deny that the "NSA" key was
built into their software.
But they refused to talk about what the key
did, or why it had been put there without users' knowledge.
A third key?!
But according to two witnesses
attending the conference, even Microsoft's top crypto programmers were
astonished to learn that the version of ADVAPI.DLL shipping with Windows
2000 contains not two, but three keys.
Brian LaMachia, head of CAPI
development at Microsoft was "stunned" to learn of these discoveries, by
outsiders. The latest discovery by Dr van Someren is based on advanced
search methods which test and report on the "entropy" of programming
Within the Microsoft organization, access to Windows source code is said
to be highly compartmentalized, making it easy for modifications to be
inserted without the knowledge of even the respective product managers.
Researchers are divided about whether the NSA key could be intended to
let US government users of Windows run classified cryptosystems on their
machines or whether it is intended to open up anyone's and everyone's
Windows computer to intelligence gathering techniques deployed by NSA's
burgeoning corps of "information warriors".
According to Fernandez of Cryptonym, the result of having the secret key
inside your Windows operating system,
"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".
The NSA key is contained inside all versions
of Windows from Windows 95 OSR2 onwards.
"For non-American IT managers relying on
Windows NT to operate highly secure data centers, this find is
worrying", he added.
"The US government is currently making it as
difficult as possible for "strong" crypto to be used outside of the
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".
"How is an IT manager to feel when they learn that in every copy of
Windows sold, Microsoft has a 'back door' for NSA - making it orders
of magnitude easier for the US government to access your computer?"
Can the loophole be turned round against the
Dr van Someren feels that the primary
purpose of the NSA key inside Windows may be for legitimate US
But he says that there cannot be a
legitimate explanation for the third key in Windows 2000 CAPI.
"It looks more fishy", he said.
Fernandez believes that NSA's built-in
loophole can be turned round against the snoopers.
The NSA key inside CAPI can be replaced by
your own key, and used to sign cryptographic security modules from
overseas or unauthorised third parties, unapproved by Microsoft or the
NSA. This is exactly what the US government has been trying to prevent.
A demonstration "how to do it" program that
replaces the NSA key
can be found on Cryptonym's website.
According to one leading US cryptographer, the IT world should be
thankful that the subversion of Windows by NSA has come to light before
the arrival of CPUs that handles encrypted instruction sets.
These would make the type of discoveries
made this month impossible.
"Had the next-generation CPU's with
encrypted instruction sets already been deployed, we would have
never found out about NSAKEY."