Rootkit infection (Popureb) requires Windows reinstall, says Microsoft


Virus Guy

I'm still running Windows 98, and I'm still immune to these rootkits.

This is also why I'd never use NTFS for any NT-based OS. It's FAT32 all
the way, baby.


Rootkit infection requires Windows reinstall, says Microsoft
New malware hides in the PC's Master Boot Record, fools cleaning
By Gregg Keizer
June 27, 2011 01:25 PM ET

Computerworld - Microsoft is telling Windows users that they'll have to
reinstall the operating system if they get infected with a new rootkit
that hides in the machine's boot sector.

A new variant of a Trojan Microsoft calls "Popureb" digs so deeply into
the system that the only way to eradicate it is to return Windows to its
out-of-the-box configuration, Chun Feng, an engineer with the Microsoft
Malware Protection Center (MMPC), said last week on the group's blog.

"If your system does get infected with Trojan:Win32/Popureb.E, we advise
you to fix the MBR and then use a recovery CD to restore your system to
a pre-infected state," said Feng.

A recovery disc returns Windows to its factory settings.

Malware like Popureb overwrites the hard drive's master boot record
(MBR), the first sector -- sector 0 -- where code is stored to bootstrap
the operating system after the computer's BIOS does its start-up checks.
Because it hides on the MBR, the rootkit is effectively invisible to
both the operating system and security software.

According to Feng, Popureb detects write operations aimed at the MBR --
operations designed to scrub the MBR or other disk sectors containing
attack code -- and then swaps out the write operation with a read

Although the operation will seem to succeed, the new data is not
actually written to the disk. In other words, the cleaning process will
have failed.

Feng provided links to MBR-fixing instructions for XP, Vista and Windows

Rootkits are often planted by attackers to hide follow-on malware, such
as banking password-stealing Trojans. They're not a new phenomenon on

In early 2010, for example, Microsoft contended with a rootkit dubbed
"Alureon" that infected Windows XP systems and crippled machines after a
Microsoft security update.

At the time, Microsoft's advice was similar to what Feng is now offering
for Popureb.

"If customers cannot confirm removal of the Alureon rootkit using their
chosen anti-virus/anti-malware software, the most secure recommendation
is for the owner of the system to back up important files and completely
restore the system from a cleanly formatted disk," said Mike Reavey,
director of the Microsoft Security Response Center (MSRC), in February

Since then, Microsoft has added a check for the Aluereon rootkit to all
security updates so that when the malware is detected, the updates are
not installed.

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