Five Steps to Ditching Malware

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Five Steps to Ditching Malware
Security scams abound, but here are some practical ways to clean up
the mess.

Michael Horowitz, Computerworld
Apr 17, 2009 9:24 am

Malware (malicious software) seems to be getting worse. No surprise,
since there's big money in it as a recent article in the Wall Street
Journal pointed out. Typical scams aim to scare unsophisticated users
with phony warnings that their computer is infected with a virus.
Conveniently, the warning is followed by prompts to install software
to remove the virus. Victims pay for the phony antivirus software and
end up infected to boot.

The term for this is scareware. A recent Microsoft report found one
particular scareware program installed on 4.4 million computers.
Scareware is not something that Vista's UAC can prevent since the user
invites it in. Among the scareware programs are Antivirus'09, Personal
Antivirus, WinDefender 2008, P Antispyware 09, WinPC Antivirus,
RapidAntivirus, WinAntivirus, XP Antivirus and DriveCleaner.

So, many people need malware removal. But how?

I suggest that the first step be to make a disk image backup of the
infected machine. A disk image backup insures that all your files are
backed up. No matter how well meaning any person or software may be,
things can go wrong in the cleanup process.

Any worthwhile disk image backup program should be able to run from a
bootable CD or USB flash drive and write the backup to an external
hard drive or another computer on a LAN. You should then be able to
mount the backup on another computer and copy off individual files as

If the important files on the infected computer are few in number,
then you might boot the machine using a Linux Live CD or a bootable
USB flash drive running Linux. I'm partial to Ubuntu, but there are
many Linux distributions that can run from a bootable CD and/or USB
flash drive. As with the disk image backup, Linux should be able to
copy files to an external hard drive or another machine on a LAN. If
the files are small enough, they can be copied to a USB flash drive.

The worst option is the one most people probably use. Install anti-
malware software on the infected machine and let it try to remove the

What makes this a poor option is that much of the current crop of
malware is sophisticated and defends itself well. The big money to be
made peddling malware draws talented programmers. To see this up close
and personal, take a look at the SRI International Technical Report An
Analysis of Conficker's Logic and Rendezvous Points. It's obvious from
the report how much care and effort went into constructing Conficker.

You have to think of the infected copy of Windows as your enemy rather
than your friend.

That's why my two suggestions so far involved not running the infected
OS at all. Any solution that involves running the infected copy of
Windows is suspect because the OS itself is suspect.

As Roger Grimes put it "... don't let a well-meaning friend or
computer geek talk you into merely scanning and "removing" the malware
and hoping for the best."

The next best option is to run anti-malware in safe mode. While this
is better than booting normally, it's still not optimal. Yes, safe
mode prevents many auto-started programs from running, but the malware
may have infected the operating system itself.

In my previous posting, I discussed rootkits and how they can modify
the operating system to hide their files. That's only one way that
rootkit software can compromise the system. It might also, for
example, hide its process. Once Windows has been compromised, you
can't count on safe mode to provide a truly clean environment.

For anti-malware software to have the best chance of detecting and
removing an infection it has to see all the files and all the
processes. In other words, it needs to run on a clean system. Kind of
ironic actually.

The best way to accomplish this is to remove the infected hard drive
from the infected computer and connect it as a data (non-booting)
drive on a clean system. I discussed this too in my previous posting.

Is this extra effort worthwhile?

I think so. As you do more and more things with your computer, it
becomes more valuable, both to you and to the bad guys.

Security maven Steve Gibson recently mentioned that's what he did when
cleaning up a computer for a friend.

There are many good anti-malware programs. Previously, on this blog,
I've written about Malwarebytes' Anti-Malware, Avira Antivirus and
Microsoft's Malicious Software Removal Tool.

The most important point is not to try and find the best program but
to use more than one. No program is perfect.

Back in January, I wrote about Avira Antivirus finding malware to
remove after many other anti-malware programs had removed what they
found from a terribly infected machine. Likewise, my experience
sending suspicious files to confirms that the best
approach is to use multiple products. I suggest running at least three
anti-malware programs, five is better.

But even that's not really sufficient.

After removing malware and restoring the hard drive back to the
original computer, you should probably run a couple anti-rootkit
scanners before connecting the machine to any network. I've had very
good luck with the free GMER scanner. RootkitRevealer is meant for
techies and comes from a trustworthy source (Bryce Cogswell and Mark
Russinovich of Microsoft) but hasn't been updated in a few years. Many
companies offering antivirus software also offer dedicated anti-
rootkit software.

Up till now, the choices have been easy; safe mode is better than a
normal boot and removing the hard disk is better than safe mode. But
is even removing the hard disk sufficient? Should you instead give up
and walk away* from an infected copy of Windows without even bothering
to do any remediation?

Tough call.

Leo Notenboom, the man behind says

Once your machine has been infected, it's not your machine any more.
Trying to remove an infection is the most common approach, and it
often works; problem is there's no way to be absolutely certain.
Thinking that you've cleared an infection and being wrong can, in the
long run, cost more time, effort and risk of data loss than simply
biting the bullet, reinstalling and being sure.

For more on this from Leo, see My anti-virus performed a virus removal
but I still have a symptom, how do I get rid of it?

Roger Grimes over at InfoWorld is also a proponent of a fresh, clean
OS installation rather than remediation. He says

Don't simply dismiss today's computer exploitations as an annoyance
like we did just a few years ago. That was play time; this is
serious. ... 99 percent of malware is crimeware designed to hurt you
financially. If you discover that a malware program is active on your
computer, you don't want to take any chances. Even if your antivirus
program tells you it is simple adware, don't take any chances ...
Today's malware exists to steal your money, whether it be through your
identity, passwords, data, or bank account. There is no way to tell
how the malware has modified your computer beyond the rogue
executables you or your antivirus program has found. There is no
antivirus removal program that can be guaranteed to have completely
cleaned your machine. Your livelihood is at stake. So don't fight
malware -- eradicate it!

The easy solutions are sub-optimal and the better solutions are,
frankly, a huge pain in the neck.

Defensive computing, preparing for trouble ahead of time, is the way
to go. Leo Notenboom agrees, "Prevention - through appropriate tools,
technologies and behaviors - is much easier and cheaper than the cure"
he says.

When prevention fails, you want to have a old, clean disk image backup
to fall back on. It's a far better option than either a clean OS
install or removing the hard drive to scan it from a clean machine.
More about that next time.

Note: For someone with a Windows OS CD, "walk away" refers to booting
from the CD and doing a clean install which results in a new fresh
copy of Windows and nothing else. You may have to follow this by
hunting down drivers, or there may also be a driver CD from the
computer manufacturer. If you have recovery CDs or a recovery DVD,
then "walk away" refers to using those to restore the computer to a
factory fresh state. This includes recovering the software that the
hardware manufacturer pre-installs. Another common option is to
restore the computer to factory fresh state using a hidden copy of
Windows on the hard drive. The procedures for invoking this type of
recovery vary.

Re: Five Steps to Ditching Malware

Ablang wrote:
Quoted text here. Click to load it

Unrealistic hogwash. In the real world such a strategy is unrealistic. How
is an 'unsophisticated' user suppose to manage backups? How is such a user
supposed to get their computer up and running when 95% of new machines do
not come with a recovery disk, and only a very very small minority of users
whose machines offer the option to create a set of recovery disks ever take
up the option.


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