Online thugs are exploiting a security bug in earlier versions of Internet Explorer that allows them to remotely execute malicious code, Microsoft warned on Tuesday.
The vulnerability in IE versions 6 and 7 allows remote attackers to gain the same access to the affected PC as the local user. The bug, which stems from an invalid pointer reference, either doesn't exist in IE 8 or can't be exploited in that version, providing users with yet another strong reason to upgrade to Microsoft's latest browser.
"At this time, we are aware of targeted attacks attempting to use this vulnerability," a member of Microsoft's security team wrote in an advisory. "In a web-based attack scenario, an attacker could host a web site that contains a web page that is used to exploit this vulnerability. In addition, compromised web sites and web sites that accept or host user-provided content or advertisements could contain specially crafted content that could exploit this vulnerability."
Microsoft didn't provide additional details about the targeted attacks.
The IE vulnerability is separate from one disclosed last week that allows attackers to remotely execute malware by tricking users into pressing the F1 button, which is typically used to present a help screen.
The advisory came on the same day that Microsoft released two security bulletins rated as "important" as part of its monthly patching regimen. One bulletin fixed vulnerabilities in Microsoft Movie Maker, which automatically ships with Windows XP and Windows Vista. The other patched holes in Microsoft Office. Reliable code exploiting many of the vulnerabilities is likely to be developed, Microsoft warned. "Important" is the second-highest setting on Microsoft's five-tier severity rating scale. ®