This security update resolves multiple privately reported vulnerabilities in the Microsoft Server Message Block (SMB) protocol. These vulnerabilities (KB958687) could potentially allow remote code execution on affected systems. An attacker who successfully exploited these vulnerabilities could install programs; view, change, or delete data; or create new accounts with full user rights. Adopting firewall best practices and standard default firewall configurations can help protect networks from attacks originating outside the enterprise. As a best practice, systems connected to the Internet should expose as few ports as possible.