"Patch Tuesday" is the day each month that Microsoft releases their newest security updates, typically the second Tuesday of the month.  This month includes six updates, including four marked "critical", and two rated as "important".  For a full breakdown, check out the Microsoft Security Bulletin posted on line. 

 

One of the critical patches involves all versions of Internet Explorer from 6 to 9, so this affects just about everyone.   This cumulative security update for Internet Explorer resolves five privately reported vulnerabilities in Internet Explorer. The most severe vulnerabilities could allow remote code execution if a user views a specially crafted webpage using Internet Explorer. An attacker who successfully exploited any of these vulnerabilities could gain the same user rights as the current user. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.

 

A "critical" patch is defined by Microsoft as "a vulnerability whose exploitation could allow the propagation of an Internet worm without user action".  As a general rule, all critical patches should be installed as soon as possible. Note that many of the patches require a reboot for installation.

A piece of malware called "Flashback" has quietly been evolving and spreading over the past several months and now affects over 600,000 Mac computers world wide.  The scary thing about this type of malware is that it is a type of "drive by" malware, which means that it doesn't involve any sort of social engineering designed to trick you into giving information.  If you merely visit an infected web page with your Mac, you can get infected.

  

Once Flashback succeeds in infecting your Mac, it inserts itself into the Safari browser and harvests information from your internet browsing activities, including usernames and passwords. It then sends this information to command-and-control servers on the internet. 

  

Apple has issued a knowledgebase article on the attack, and you can also read more about the background on ZDNet.

 

Yes, you DO need to have antivirus software installed and up to date on your Mac.  We get asked about this all the time:  Macs are NOT immune to viruses.  Also, always keep your Java and Adobe updates current.

Microsoft's IE Reclaims Lost Ground in the Browser Battles -  Browser preferences change over time.  See which browsers are the most popular and how many people use them.   Read more on CNET.