Page last updated at 09:30 GMT, Friday, 16 April 2010 10:30 UK

Infected XP owners left unpatched

Windows XP on sale, PA
Only those running Windows XP have been left without a patch

Some of the latest security updates for Windows XP will not be installed on machines infected with a rootkit virus.

A rootkit is sneaky malware that buries itself deep inside the Windows operating system to avoid detection.

Microsoft said it had taken the action because similar updates issued in February made machines infected with the Alureon rootkit crash endlessly.

The latest updates can spot if a system is compromised by the Alureon rootkit and halt installation.

Find and fix

The latest batch of updates for Windows was released on 16 April and some of them fix vulnerabilities in the core, or kernel, of Windows. This is the same place that rootkits try to take up residence.

When Alureon is present it monitors net traffic and plucks out user names, passwords and credit card numbers. It also gives attackers a back door into infected machines.

The virus first appeared in 2008 and has been spread via discussion forums, hacked websites and bogus pay-per-click affiliate schemes.

FREE ANTI-ROOTKIT TOOLS
AVG
Avira
F-Secure - Blacklight
McAfee
Panda
Sophos
Trend Micro

Notes for the security patch explained which "abnormal conditions" would prevent XP users applying the updates.

"These abnormal conditions on a system could be the result of an infection with a computer virus that modifies some operating system files, which renders the infected computer incompatible with the kernel update," read the statement.

By not applying the patch, Microsoft hopes to avoid a repeat of events in February which left many people struggling to get their computer working again.

Microsoft also wants to avoid a situation in which people become wary of updates because they provoke a crash.

It is not yet clear how many people have been left without the updates.

Microsoft urged those who are infected to ensure their machine is cleaned of the rootkit. It recommended using its malware removal tool or using rootkit detectors from other security companies.

Many modern security packages have them built in and will find rootkits when a machine is scanned.



Print Sponsor


SEE ALSO
Botnet shutdown divides experts
26 Feb 10 |  Technology
Microsoft tackles 17-year-old bug
05 Feb 10 |  Technology
Google phases out support for IE6
30 Jan 10 |  Technology
Microsoft patches Explorer hole
21 Jan 10 |  Technology
Microsoft readies bumper update
12 Oct 09 |  Technology
Microsoft launches free security
29 Sep 09 |  Technology

RELATED INTERNET LINKS
The BBC is not responsible for the content of external internet sites



FEATURES, VIEWS, ANALYSIS
Has China's housing bubble burst?
How the world's oldest clove tree defied an empire
Why Royal Ballet principal Sergei Polunin quit

BBC navigation

BBC © 2013 The BBC is not responsible for the content of external sites. Read more.

This page is best viewed in an up-to-date web browser with style sheets (CSS) enabled. While you will be able to view the content of this page in your current browser, you will not be able to get the full visual experience. Please consider upgrading your browser software or enabling style sheets (CSS) if you are able to do so.

Americas Africa Europe Middle East South Asia Asia Pacific