By Bruce Schneier
Sept, 07, 2006
If you really want to see Microsoft scramble to patch a hole in its
software, don't look to vulnerabilities that impact countless Internet
Explorer users or give intruders control of thousands of Windows
machines. Just crack Redmond's DRM.
Security patches used to be rare. Software vendors were happy to pretend
that vulnerabilities in their products were illusory -- and then quietly
fix the problem in the next software release.
That changed with the full disclosure movement. Independent security
researchers started going public with the holes they found, making
vulnerabilities impossible for vendors to ignore. Then worms became more
common; patching -- and patching quickly -- became the norm.
But even now, no software vendor likes to issue patches. Every patch is
a public admission that the company made a mistake. Moreover, the
process diverts engineering resources from new development. Patches
annoy users by making them update their software, and piss them off even
more if the update doesn't work properly.
For the vendor, there's an economic balancing act: how much more will
your users be annoyed by unpatched software than they will be by the
patch, and is that reduction in annoyance worth the cost of patching?
Since 2003, Microsoft's strategy to balance these costs and benefits has
been to batch patches: instead of issuing them one at a time, it's been
issuing them all together on the second Tuesday of each month. This
decreases Microsoft's development costs and increases the reliability of
The user pays for this strategy by remaining open to known
vulnerabilities for up to a month. On the other hand, users benefit from
a predictable schedule: Microsoft can test all the patches that are
going out at the same time, which means that patches are more reliable
and users are able to install them faster with more confidence.
In the absence of regulation, software liability, or some other
mechanism to make unpatched software costly for the vendor, "Patch
Tuesday" is the best users are likely to get.
Why? Because it makes near-term financial sense to Microsoft. The
company is not a public charity, and if the internet suffers, or if
computers are compromised en masse, the economic impact on Microsoft is
Microsoft is in the business of making money, and keeping users secure
by patching its software is only incidental to that goal.
There's no better example of this of this principle in action than
Microsoft's behavior around the vulnerability in its digital rights
management software PlaysForSure.
Last week, a hacker developed an application called FairUse4WM that
strips the copy protection from Windows Media DRM 10 and 11 files.
Now, this isn't a "vulnerability" in the normal sense of the word:
digital rights management is not a feature that users want. Being able
to remove copy protection is a good thing for some users, and completely
irrelevant for everyone else. No user is ever going to say: "Oh no. I
can now play the music I bought for my PC on my Mac. I must install a
patch so I can't do that anymore."
But to Microsoft, this vulnerability is a big deal. It affects the
company's relationship with major record labels. It affects the
company's product offerings. It affects the company's bottom line.
Fixing this "vulnerability" is in the company's best interest; never
mind the customer.
So Microsoft wasted no time; it issued a patch three days after learning
about the hack. There's no month-long wait for copyright holders who
rely on Microsoft's DRM.
This clearly demonstrates that economics is a much more powerful
motivator than security.
It should surprise no one that the system didn't stay patched for long.
FairUse4WM 1.2 gets around Microsoft's patch, and also circumvents the
copy protection in Windows Media DRM 9 and 11beta2 files.
That was Saturday. Any guess on how long it will take Microsoft to patch
Media Player once again? And then how long before the FairUse4WM people
update their own software?
Certainly much less time than it will take Microsoft and the recording
industry to realize they're playing a losing game, and that trying to
make digital files uncopyable is like trying to make water not wet.
If Microsoft abandoned this Sisyphean effort and put the same
development effort into building a fast and reliable patching system,
the entire internet would benefit. But simple economics says it probably
Bruce Schneier is the CTO of Counterpane Internet Security and the
author of Beyond Fear: Thinking Sensibly About Security in an Uncertain
World. You can contact him through his website.
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