Microsoft on Tuesday released two security bulletins that patched four vulnerabilities its Internet Explorer browser and one in its Windows 2000 operating system. Two of the vulnerabilities were tagged by Microsoft as "critical."
As expected, one of the four fixes for IE is a patch for the zero-day vulnerability acknowledged by Microsoft in late November.
Microsoft's first bulletin, MS050-054, fixes four separate bugs in Internet Explorer, two of them marked with Microsoft's most serious label, critical.
Those two relate to IE's problem handling malicious COM objects and a more recent issue that's emerged with active scripting. Attackers exploiting the problems can grab control of a PC remotely, then do whatever they want with the compromised machine.
The other two flaws fixed Tuesday in IE were marked "moderate" by Microsoft.
All four issues affect virtually every version of IE still supported, including IE 5.0, 5.5, and 6.0. Even the more secure IE 6.0 running under Windows XP SP2 is vulnerable.
Some of the bugs rely on social engineering tricks -- one vulnerability lies in the how IE displays file download boxes -- but all require that users be duped into visiting malicious Web sites where exploits were waiting in ambush.