By Jaikumar Vijayan
June 14, 2006
Security firms are warning about the availability of attack code
targeting some of the flaws for which Microsoft Corp. released patches
yesterday (see "Microsoft releases fixes for 21 vulnerabilities" ).
Most of the exploits target flaws that were previously known but for
which patches became available only as part of Microsoft's June
monthly security update. But at least two publicly available exploits
are directed at newly disclosed flaws in the company's products.
"Exploit code had already existed for three of the vulnerabilities
prior to yesterday, as they were already public issues," said Michael
Sutton, director of VeriSign Inc.'s iDefense Labs. "Beyond that, we're
seeing public exploit code emerge for some of the new vulnerabilities
and are hearing rumors of private code existing for others."
The availability of such exploits heightens the risk for companies
that have not yet been able to patch their systems and are important
factors to consider when deciding which systems to patch first, he
"We believe that it is far more beneficial to withhold
proof-of-concept code for an amount of time so that customers can get
the vulnerabilities patched," said Stephen Toulouse, security program
manager at Microsoft's security response center. "The public
broadcasting of code so quickly after a bulletin release, we believe,
tends to help attackers."
Microsoft is telling its cusomers to pay special attention to three
key updates -- MS06-021, MS06-022 and MS06-023 -- because they could
be particularly easy to exploit using Internet Explorer. "There are
methods by which if you just browse to a Web site, there could be code
execution," Toulouse said.
According to iDefense, some form of exploit code is publicly available
against the cross-domain information disclosure vulnerability
described in bulletins MS06-021, the address bar spoofing flaw in
MS06-021 and the Word malformed object pointer vulnerability described
All three were previously known flaws and were given a severity rating
of "critical" by Microsoft.
In addition, exploits have also become publicly available for both of
the newly disclosed server message block vulnerabilities in MS06-030,
according to iDefense.
The SANS Internet Storm Center this morning posted a note also listing
exploits released by penetration-testing vendors to customers. One of
the exploits was directed against the Windows Media Player flaw in
MS06-024, while the other was targeted at the routing and
remote-access vulnerability in MS06-025.
Denial-of-service attack codes are also privately available for a
TCP/IP flaw in MS06-032, according to SANS.
Outside of the Word malware, which began circulating last month,
Microsoft has not yet seen any of these exploits used by attackers,
The availability of exploit code once again shows that there is no
longer any "patching window" for companies, said Johannes Ullrich,
chief research officer at the Internet Storm Center.
"Companies don't have the luxury of sitting back and waiting," Ullrich
said. "They have to expect that public exploits will become available
the day after vulnerabilities are disclosed, and they have to expedite
the patching process," despite the challenges involved, he said.
Robert McMillan of the IDG News service contributed to this report.
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