A serious security hole was recently discovered in one of the Internet's backbone services, known as DNS, which is responsible for translating human-readable labels (such as www.google.com) into specific computer addresses - it underpins the the entire World Wide Web.
Attackers could exploit this DNS weakness, resulting in users being sent to bogus sites that contains malicious code which attempts to compromise their computer. Alternatively the bogus sites could masquerade as the 'official' site (an increasingly popular attack, know as 'phishing'). Or it could do both.
The attack is performed by 'poisoning' a local copy of the DNS database - anyone who subsequently uses that database is at risk, but would be completely unaware and not have done anything wrong themselves.
Software from many companies has been found vulnerable to this attack and fixes have been rushed out; this includes Microsoft, as well as Debian, Ubuntu, Redhat, Sun and Cisco - many more vendors are also thought to be vulnerable but are unconfirmed at present.
Unfortunately not all the fixes have been successful; in particular the Microsoft patch appears to have disabled the Internet connection for many Windows systems, particularly where ZoneAlarm has also been installed.
ZoneLabs have worked around the Microsoft problem and issued a new release, but users will need to manually uninstall the Microsoft 'fix' so they can get back on the Internet first! This can be done via the Windows 'Control Panel', using 'Add/Remove Programs' to uninstall the update identified as KB951748.
Despite the teething problems we strongly urge all computers users (Windows, Linux, Mac, etc) to ensure that their system has all the latest security patches installed as soon as practicable; this security hole has been very public and affects many, many systems so it won't be long before attackers understand the weakness and start exploiting it.
On a similar theme, please note that 'phishing' attack are increasing dramatically at the moment, especially within the UK (more than tripled in the first three months of this year, compared with 2007).
Protect your computers by installing all the latest security patches for your operating-system and use an up-to-date anti-malware product (we recommend Grisoft products) if you don't already - these will protect your from viruses, as well as 'phishing' attacks and other risks.
It may also be worth evaluating the free Firefox browser if you don't already use it - a recent report has shown that Firefox users are generally safer online, due to the way it automatically updates itself.
