Microsoft released a security update that resolves a privately reported vulnerability in the JScript scripting engine that could allow remote code execution if a user opened a specially crafted file or visited a specially crafted Web site and invoked a malformed script.
If a user is logged on with administrative user rights, an attacker who successfully exploited this vulnerability could take complete control of an affected system. An attacker could then install programs; view, change, or delete data; or create new accounts with full user rights. 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.
This security update is rated Critical for JScript 5.1 on Microsoft Windows 2000 Service Pack 4 and Critical for JScript 5.6, JScript 5.7 and JScript 5.8 on all supported releases of the Windows operating system except Windows 7 and Windows Server 2008 R2.
This security update addresses the vulnerability by modifying the way that the JScript engine processes scripts in Web pages.
For administrators and enterprise installations, or end users who want to install this security update manually, Microsoft recommends that customers apply the update immediately using update management software, or by checking for updates using the Microsoft Update service.