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Safeguard Your PC Against the Downadup Worm
How to protect your PC from the biggest worm in years.
Gregg Keizer, Computerworld
Jan 20, 2009 2:10 pm
http://www.pcworld.com/article/158016/article.html?tk=nl_dnxnws
Security experts say it's the biggest worm attack in years, call it
"amazing" and report that it infected nearly 9 million PCs in just two
weeks.
Downadup is downright nasty. And that's even before it does much more
than just spread.
But as analysts argue about how the compromised computers will be used
-- to build a massive, new botnet, perhaps -- or how much information
hackers will steal from infected machines, users like you have a more
immediate concern: "How do I keep my PC from joining the ranks of the
hacked?"
That's a simple question. Unfortunately, because of this worm's
flexibility, the answers aren't.
What's the worm again? Thanks to the lack of an industry-wide labeling
system, the worm goes by more than one name. Some companies dub it
"Downadup," others call it "Conficker."
No matter the name, it's the same threat.
When did Downadup first appear? Security companies warned of the worm
in late November 2008; Symantec Corp. was one of the first to sound
the alarm when it raised its ThreatCon security alert level on Nov.
21. Within a week, Microsoft had added its voice to the chorus as it
acknowledged a significant uptick in attacks.
However, the worm only really took off about a week ago as newer
variations struck users and resulted in millions of infections.
How does it spread? One of Downadup's most intriguing aspects, say
security researchers, is its multi-pronged attack strategy: It can
spread three different ways.
The one that's gotten the most attention exploits a vulnerability in
Windows that Microsoft Corp. patched nearly four months ago. The bug,
which is in a file-sharing service that's included in all versions of
the OS, can be exploited remotely just by sending a malformed data
packet to an unpatched PC.
But the worm can also spread by brute-force password attacks, and by
copying itself to any removable USB-based devices such as flash drives
and cameras. More on those two in a moment.
What machines are most vulnerable to Downadup attack? According to
Microsoft, unpatched Windows 2000, Windows XP and Windows Server 2003
machines are at the greatest risk to exploits of the bug patched in
October. That gibes with reports from security companies, which have
highlighted the danger to PCs running Windows XP Service Pack 2 (SP2)
and XP SP3. Not coincidentally, those versions account for the bulk of
Windows' market share.
Unpatched Windows Vista and Server 2008 systems, meanwhile, are less
likely to fall victim to attack since hackers must have authenticated
access to the computer, or in other words, know the log-in username
and password.
Any Windows-powered machines, however, can be compromised by the
worm's password and USB attack strategies.
I'm running Windows 7 beta...am I safe? According to the Microsoft
support document that details the October patch, yes you are.
Microsoft offered the fix as a security patch to users of the Windows
7 "pre-beta," the version it gave developers in late October and early
November. It then integrated the patch into Windows 7 before it
launched the public beta on Jan. 10.
Okay, so how do I protect my PC? Because this thing is a triple-
threat, you'll need to take more than one defensive measure.
First of all, if you haven't already done so, apply the October fix
that Microsoft tagged as MS08-067. If you have Windows Update set to
automatically download and install patches, you should be protected,
but it never hurts to double-check. You can verify that the patch has
been installed by bringing up Windows Update, then clicking "Review
your update history" and looking for a security update labeled as
"KB958644."
If you are only now installing the patch, you might want to take
Microsoft's advice and also download and install the January edition
of its free Malicious Software Removal Tool (MSRT), which was updated
last week so that it can detect, and then delete, Downadup infections.
What's this about password attacks? Although most of the news about
Downadup's spread has focused on its exploitation of a patched bug in
Windows, the worm also propagates by trying to guess other machines'
administrative passwords.
Once the worm penetrates a corporate network -- perhaps by infecting a
single unpatched machine, say a laptop, that is later connected to
that network -- it tries to break into other PCs, including those that
have been patched with the October emergency fix.
"One of the ways in which the Conficker worm (also known as Confick or
Downadup) uses to spread is to try and batter its way into ADMIN$
shares using a long list of different passwords," said Graham Cluley,
a senior technology consultant at Sophos, in an entry to a company
blog last Friday. Cluley included the list of passwords that Downadup
tries, which range from the ubiquitous "password" and the moronic
"secure" to the slightly-more-clever "letmein" and "nimda," or "admin"
spelled backward.
Cluley urged users to steer clear of what he called "poorly-chosen
passwords," while other security companies recommended that users not
only pick stronger passwords but change them periodically as well.
Obviously, if you're using a password that's on the Downadup list, you
should change it immediately.
And the worm can spread from flash drives, too? Yes.
From the moment Downadup infects a PC, it copies a file, named
"autorun.inf" to the root of any USB storage devices, typically flash
drives, that are connected to the compromised computer. That filename
takes advantage of Windows' Autorun and Autoplay features to copy the
worm to any machine that the flash drive, camera or other USB device
is plugged into. Downadup will infect that PC when the drive or device
is connected, or when the user double-clicks the device's icon within
Windows Explorer or from the desktop.
Security experts have recommended that users disable both Autorun and
Autoplay in Windows.
A December blog post by Symantec researcher Ben Nahorney spells out
how to disable Autoplay, while a separate post on the Hackology blog
outlines how to turn off Autorun by editing the registry.
What are the signs that my PC has been hit? Microsoft's advisory about
Downadup lists several symptoms of infection, including:
*
Account lockout policies are being tripped (because your
password's been hijacked, then changed by the attacker)
*
Automatic Updates are disabled (because Downadup tries to keep
the PC unpatched by turning off Windows Update's automatic update, as
well as Background Intelligent Transfer Service (BITS), the Windows
component used by Windows Update to actually deliver the updates)
*
Various security-related Web sites cannot be accessed (because
Downadup blocks access to a whole host of security companies' sites in
an effort to prevent anti-virus software from being updated, which
could result in the worm's detection and eradication)
If your PC is exhibiting any of these symptoms -- or the others that
Microsoft spells out here -- the company recommends that you
immediately use the MSRT to clean the machine.
You can download the MSRT from Microsoft's site, or follow these
instructions posted to its support site that walk administrators
through the steps to deploy the tool in enterprise environments.
Safeguard Your PC Against the Downadup Worm
How to protect your PC from the biggest worm in years.
Gregg Keizer, Computerworld
Jan 20, 2009 2:10 pm
http://www.pcworld.com/article/158016/article.html?tk=nl_dnxnws
Security experts say it's the biggest worm attack in years, call it
"amazing" and report that it infected nearly 9 million PCs in just two
weeks.
Downadup is downright nasty. And that's even before it does much more
than just spread.
But as analysts argue about how the compromised computers will be used
-- to build a massive, new botnet, perhaps -- or how much information
hackers will steal from infected machines, users like you have a more
immediate concern: "How do I keep my PC from joining the ranks of the
hacked?"
That's a simple question. Unfortunately, because of this worm's
flexibility, the answers aren't.
What's the worm again? Thanks to the lack of an industry-wide labeling
system, the worm goes by more than one name. Some companies dub it
"Downadup," others call it "Conficker."
No matter the name, it's the same threat.
When did Downadup first appear? Security companies warned of the worm
in late November 2008; Symantec Corp. was one of the first to sound
the alarm when it raised its ThreatCon security alert level on Nov.
21. Within a week, Microsoft had added its voice to the chorus as it
acknowledged a significant uptick in attacks.
However, the worm only really took off about a week ago as newer
variations struck users and resulted in millions of infections.
How does it spread? One of Downadup's most intriguing aspects, say
security researchers, is its multi-pronged attack strategy: It can
spread three different ways.
The one that's gotten the most attention exploits a vulnerability in
Windows that Microsoft Corp. patched nearly four months ago. The bug,
which is in a file-sharing service that's included in all versions of
the OS, can be exploited remotely just by sending a malformed data
packet to an unpatched PC.
But the worm can also spread by brute-force password attacks, and by
copying itself to any removable USB-based devices such as flash drives
and cameras. More on those two in a moment.
What machines are most vulnerable to Downadup attack? According to
Microsoft, unpatched Windows 2000, Windows XP and Windows Server 2003
machines are at the greatest risk to exploits of the bug patched in
October. That gibes with reports from security companies, which have
highlighted the danger to PCs running Windows XP Service Pack 2 (SP2)
and XP SP3. Not coincidentally, those versions account for the bulk of
Windows' market share.
Unpatched Windows Vista and Server 2008 systems, meanwhile, are less
likely to fall victim to attack since hackers must have authenticated
access to the computer, or in other words, know the log-in username
and password.
Any Windows-powered machines, however, can be compromised by the
worm's password and USB attack strategies.
I'm running Windows 7 beta...am I safe? According to the Microsoft
support document that details the October patch, yes you are.
Microsoft offered the fix as a security patch to users of the Windows
7 "pre-beta," the version it gave developers in late October and early
November. It then integrated the patch into Windows 7 before it
launched the public beta on Jan. 10.
Okay, so how do I protect my PC? Because this thing is a triple-
threat, you'll need to take more than one defensive measure.
First of all, if you haven't already done so, apply the October fix
that Microsoft tagged as MS08-067. If you have Windows Update set to
automatically download and install patches, you should be protected,
but it never hurts to double-check. You can verify that the patch has
been installed by bringing up Windows Update, then clicking "Review
your update history" and looking for a security update labeled as
"KB958644."
If you are only now installing the patch, you might want to take
Microsoft's advice and also download and install the January edition
of its free Malicious Software Removal Tool (MSRT), which was updated
last week so that it can detect, and then delete, Downadup infections.
What's this about password attacks? Although most of the news about
Downadup's spread has focused on its exploitation of a patched bug in
Windows, the worm also propagates by trying to guess other machines'
administrative passwords.
Once the worm penetrates a corporate network -- perhaps by infecting a
single unpatched machine, say a laptop, that is later connected to
that network -- it tries to break into other PCs, including those that
have been patched with the October emergency fix.
"One of the ways in which the Conficker worm (also known as Confick or
Downadup) uses to spread is to try and batter its way into ADMIN$
shares using a long list of different passwords," said Graham Cluley,
a senior technology consultant at Sophos, in an entry to a company
blog last Friday. Cluley included the list of passwords that Downadup
tries, which range from the ubiquitous "password" and the moronic
"secure" to the slightly-more-clever "letmein" and "nimda," or "admin"
spelled backward.
Cluley urged users to steer clear of what he called "poorly-chosen
passwords," while other security companies recommended that users not
only pick stronger passwords but change them periodically as well.
Obviously, if you're using a password that's on the Downadup list, you
should change it immediately.
And the worm can spread from flash drives, too? Yes.
From the moment Downadup infects a PC, it copies a file, named
"autorun.inf" to the root of any USB storage devices, typically flash
drives, that are connected to the compromised computer. That filename
takes advantage of Windows' Autorun and Autoplay features to copy the
worm to any machine that the flash drive, camera or other USB device
is plugged into. Downadup will infect that PC when the drive or device
is connected, or when the user double-clicks the device's icon within
Windows Explorer or from the desktop.
Security experts have recommended that users disable both Autorun and
Autoplay in Windows.
A December blog post by Symantec researcher Ben Nahorney spells out
how to disable Autoplay, while a separate post on the Hackology blog
outlines how to turn off Autorun by editing the registry.
What are the signs that my PC has been hit? Microsoft's advisory about
Downadup lists several symptoms of infection, including:
*
Account lockout policies are being tripped (because your
password's been hijacked, then changed by the attacker)
*
Automatic Updates are disabled (because Downadup tries to keep
the PC unpatched by turning off Windows Update's automatic update, as
well as Background Intelligent Transfer Service (BITS), the Windows
component used by Windows Update to actually deliver the updates)
*
Various security-related Web sites cannot be accessed (because
Downadup blocks access to a whole host of security companies' sites in
an effort to prevent anti-virus software from being updated, which
could result in the worm's detection and eradication)
If your PC is exhibiting any of these symptoms -- or the others that
Microsoft spells out here -- the company recommends that you
immediately use the MSRT to clean the machine.
You can download the MSRT from Microsoft's site, or follow these
instructions posted to its support site that walk administrators
through the steps to deploy the tool in enterprise environments.
