Microsoft has admitted that a recent software patch for
its Windows operating system is causing some Windows 2000 machines
to stop responding after it is installed.
Some systems that use the security update, MS04-011, stop
responding when they start up, prevent users from logging on to
Windows, or bog down, Microsoft said.
The security patch was released on 13 April and fixes a number
of holes in Windows, including problems with Windows implementation
of Secure Sockets Layer (SSL), a protocol frequently used to secure
communications between servers and clients on public networks and
the internet.
Included in the patch is a fix for a buffer overrun in the
Private Communications Transport (PCT) protocol, which is part of
Microsoft's SSL library. PCT is a protocol in that library that was
developed by Microsoft and Visa International to conduct encrypted
communication on the internet.
Shortly after Microsoft released that patch, malicious code that
could be used to trigger the PCT buffer overflow and compromise
Windows systems appeared on the internet. In recent days, security
companies warned of widespread attacks that use the exploit code,
though the code has not yet been tied to a virus or Internet
worm.
An attacker who could exploit the PCT hole could take complete
control of affected systems, installing programs, viewing,
modifying or deleting data or changing user access to the
system.
Since releasing the patch, Microsoft has encouraged customers to
apply the it as soon as possible. However, now it appears that the
patch comes with its own problems.
Microsoft said that a software change in the patch causes
Windows 2000 systems to repeatedly try to load drivers that cannot
load successfully, causing the hangups. (See:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;841382.)
The company listed three software drivers that, if installed,
make Windows 2000 systems susceptible to the slowdowns. Microsoft
also described specific problems and a work-around procedure for
Windows systems that have Nortel Networks' virtual private network
client installed.
However, Microsoft acknowledged that the slowdowns may occur
with other combinations of drivers and services that do not load
successfully.
Microsoft said it is researching the slowdown problem and will
release more information when it is available.
Paul Roberts writes for IDG News
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