How NSA access was built into Windows
Duncan Campbell
04.09.1999
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"
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trapdoor
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 programmes inserted and controlled by NSA. As yet, no-one
knows what these programmes 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 NSA. 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,
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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. One was called "KEY". The other was called
"NSAKEY".
Fernandes 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 code.
Within the Microsoft organisation,
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 centres, 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 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".
"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?" he asked.
Can the loophole be turned round against
the snoopers?
Dr van Someren feels that the
primary purpose of the NSA key inside Windows may be for legitimate US
government use. 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."
