Software Engineering Institute

Server Message Block is a protocol which allows sharing of files, printers, serial ports, and other abstractions. The SMB protocol is supported on many platforms and architectures, including many Microsoft products.

The Microsoft Server Message Block implementation contains a flaw in incoming SMB packet validation that may result in a buffer receiving inappropriate data. An attacker may send a specially-crafted packet to the vulnerable host and be able to execute arbitrary code on the host after exploiting the incoming packet processing flaw.

A remote unauthenticated attacker with the ability to send specially-crafted SMB packets to a vulnerable host may be able to execute arbitrary code on that system. The attacker-supplied code would be run in the context of Local System, resulting in a complete compromise of the system.

Apply An Update

Please see Microsoft Security Bulletin MS05-027 for more information, such as workarounds and patches.

Utilize Workarounds

Microsoft recommends the following workarounds in Microsoft Security Bulletin MS05-027:

Block TCP ports 139 and 445. This will disallow attackers the ability to contact the vulnerable SMB service on the affected host(s).

Use a firewall to block unsolicited or malicious traffic.

Use IPsec to protect network communications between hosts.