Microsoft Windows is prone to a remote code-execution vulnerability that affects the Microsoft Server Message Block (SMB) protocol software. A remote attacker can exploit this issue to execute code with SYSTEM-level privileges. Failed exploit attempts will likely cause denial-of-service conditions. NOTE: To exploit this issue, an attacker must have read permissions on an SMB share on the target system. By default, Windows XP grants this access; later systems will require the attacker to authenticate to the server, or require the server to be configured in a way to automatically grant read permissions.
Block external access at the network boundary, unless external parties require service.
If global access isn't needed, filter access to the affected computer at the network boundary. Restricting access to only trusted computers and networks might greatly reduce the likelihood of exploitation.
Deploy network intrusion detection systems to monitor network traffic for malicious activity.
Deploy NIDS to monitor network traffic for signs of anomalous or suspicious activity. This includes but is not limited to requests that include explained incoming and outgoing traffic. This may indicate exploit attempts or activity that results from successful exploits.
Implement multiple redundant layers of security.
Various memory-protection schemes (such as nonexecutable and randomly mapped memory segments) may hinder an attacker's ability to exploit this vulnerability to execute arbitrary code.
A Microsoft advisory along with fixes is available. Please see the references for details.