[Infowarrior] - Microsoft admits hiding vuln details

[Richard Forno]

Microsoft Patches: When Silence Isn't Golden
April 19, 2006
By  Ryan Naraine
http://www.eweek.com/print_article2/0,1217,a=176124,00.asp

Microsoft has 'fessed up to hiding details on software vulnerabilities that
are discovered internally, insisting that full disclosure of every
security-related product change only serves to aid attackers.

The company's admission follows criticisms from a security researcher that
its policy of silently fixing software flaws is "misleading" and not in the
spirit of Microsoft's push for transparency.

In an interview with eWEEK, Mike Reavey, operations manager of the MSRC
(Microsoft Security Response Center), said the company's policy is to
document the existence of internally discovered flaws as well as the area of
functionality where the change occurred, but that full details on the fixes
are withheld for a very good reason.

"We want to make sure we don't give attackers any [additional] information
that could be used against our customers. There is a balance between
providing information to assess risk and giving out information that aids
attackers," Reavey said.

When Microsoft receives a report of a security flaw from external
researchers, Reavey said, the MSRC conducts an extensive investigation to
look at all the surrounding code to make sure a comprehensive fix is pushed
out the door. If a related bug is found internally, it will be fixed in the
eventual patch, he said, but the details will be kept under wraps.

Read more here about Microsoft's patch-creation process at the MSRC.

However, critics argue that silent fixes have a way of backfiring and
hurting businesses that depend on information from the vendor to determine
deployment time frames and the actual severity of the patched vulnerability.

According to eEye Digital Security, which sells host-based IPS (intrusion
prevention system) technology, silent fixes from Microsoft are commonplace.

"It is the skeleton in Microsoft's closet. We routinely find them," said
Steve Manzuik, product manager of eEye's security research team, in Aliso
Viejo, Calif.

In an interview with eWEEK, Manzuik said Microsoft has been silently fixing
bugs as far back as 2004. He referred to the company's MS04-007 bulletin as
a classic example of Microsoft announcing a fix for a single vulnerability
when in fact a total of seven flaws were quietly fixed.

Read details here about Microsoft's decision to use external patch testers.

Manzuik's team presented a research paper on its findings at the Black Hat
Briefings in Europe earlier in 2006 to highlight the problems with
withholding details on fixes from customers.

"Microsoft's customers depend on that information to figure out how to
respond to Patch Tuesday. The reality is, system administrators will delay
deploying a patch based on the details of the bulletin. When details aren't
included, he won't install that patch. That is a big problem," Manzuik said.

He said IT departments do not have the skill or resources to
reverse-engineer every patch.

"They are simply left in the dark and may ignore a patch that is
super-critical to their environment. Meanwhile, the bad guy has spent the
time to find out what was silently fixed," Manzuik said, arguing that
Microsoft has a responsibility to make sure businesses are fully informed
about software changes.

"I don't buy the argument that they are aiding attackers. The attackers are
already reverse-engineering the patches. They have the time and resources to
find out where the flaw lies. The guy that feels the pain is the system
administrator who is in the dark and who can't do his own
reverse-engineering," Manzuik said.

Matthew Murphy, the independent researcher who flagged the issue after
finding silent fixes in the April batch of patches, said third-party vendors
that incorporate code from Microsoft are also hurt by the lack of full
disclosure.

Murphy outlined a recent case where anti-virus vendor Trend Micro got burned
by a silent fix pushed out by Microsoft. That issue revolved around a bug in
Visual Studio that was reported to Microsoft in 2002 but remained unfixed
for several years.

Microsoft eventually fixed the bug but information was withheld, causing
Trend Micro to unwittingly use the vulnerable code in its products, putting
its customers at risk of a heap overflow vulnerability that could be used in
code execution attacks.

Manzuik also pointed out that businesses rely heavily on host-based IPS
technology to secure valuable assets while patches are being tested for
deployment.

"Some of these IPS products need information from the software vendor to
create signatures. How can you create a signature for a flaw if you don't
know the location of the flaw? We have proven that signature-based
technology can be bypassed to exploit these silently fixed flaws," he said.

Reavey said businesses should use Microsoft's severity rating system to help
with patch deployment timetables. "It's important to remember that the best
way to be safe and secure is to apply all the updates. We are providing
patches for everything. We still recommend a defense-in-depth strategy that
includes IPS and IDS [intrusion detection system] technology, but customers
should use our severity ratings system and apply the patches," he said.

Check out eWEEK.com's Security Center for the latest security news, reviews
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look at eWEEK.com Security Center Editor Larry Seltzer's Weblog.
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