The information has been provided by Cisco Systems Product Security Incident Response Team.
The original article can be found at: http://www.cisco.com/warp/public/707/cisco-sa-20071205-csa.shtml
All versions of Cisco Security Agent for Windows, either managed or standalone, are affected. Agents that are running on Cisco IP Communications application servers or agents on systems that are running the Cisco Security Manager are examples of a standalone implementation.
Standalone agents are installed in the following Cisco IP Communications products:
* Cisco Unified Communications Manager (CallManager)
* Cisco Conference Connection (CCC)
* Emergency Responder
* IPCC Express
* IPCC Enterprise
* IPCC Hosted
* IP Interactive Voice Response (IP IVR)
* IP Queue Manager
* Intelligent Contact Management (ICM)
* Cisco Voice Portal (CVP)
* Cisco Unified Meeting Place
* Cisco Personal Assistant (PA)
* Cisco Unity
* Cisco Unity Connection
* Cisco Unity Bridge
* Cisco Internet Service Node (ISN)
Cisco Security Manager installs a standalone version of Cisco Security Agent if an agent is not found when Cisco Security Manager is installed, so systems that are running Cisco Security Manager are also affected by this vulnerability.
Products Confirmed Not Vulnerable
The Cisco Secure Access Control Server (ACS) Solution Engine, also known as the ACS appliance, integrates a standalone version of Cisco Security Agent. However, the ACS Solution Engine is not affected by this vulnerability because by default it blocks incoming traffic to the affected TCP ports (139 and 445). Additional information is in the Details section.
Cisco Security Agents that are running on the Solaris and Linux operating systems are not affected by the vulnerability described in this advisory.
Cisco Security Agent is a security software agent that provides threat protection for server and desktop computing systems. Cisco Security Agents can be managed by a Management Center for Cisco Security Agents or can be standalone agents that are not managed by a Cisco Security Agent Management Center.
Some Cisco products integrate standalone Cisco Security Agents to protect the products against viruses, worms, and attacks. Examples of products that integrate standalone Cisco Security Agents include Cisco IP Communications application servers, the Cisco Secure Access Control Server (ACS) Solution Engine, and the Cisco Security Manager.
A buffer overflow vulnerability exists in a system driver used by Cisco Security Agents, whether they are managed or unmanaged. Cisco Security Agents use this driver by default.
Windows kernel memory becomes corrupted when this buffer is overflowed. Therefore, exploitation of this vulnerability will lead to a Windows stop error (kernel panic, or blue screen error), or to arbitrary code execution. The vulnerability can be exploited remotely via the network.
The vulnerability is triggered when Cisco Security Agent is processing a crafted TCP segment destined to TCP port 139 or 445. These ports are used by the Microsoft Server Message Block (SMB) protocol. A TCP session needs to be established (that is, the TCP three-way handshake needs to be completed) for the vulnerability to be triggered.
All systems that are running a vulnerable version of Cisco Security Agent for Windows are affected. This includes Cisco products that integrate standalone Cisco Security Agents, such as Cisco IP Communications applications servers and the Cisco Security Manager. Although the ACS Solution Engine integrates a standalone Cisco Security Agent, it is not affected because TCP ports 139 and 445 have been firewalled by the ACS Solution Engine itself. This blocking of traffic destined to TCP ports 139 and 445 is enabled by default and is not user-configurable.
Successful exploitation of the buffer overflow vulnerability described in this advisory may result in an operating system crash or complete system compromise.
Filters that deny SMB protocol packets using TCP ports 139 and 445 should be deployed as part of a transit access control list (tACL) policy for protection from traffic that enters the network at ingress access points. This policy should be configured to protect the network device where the filter is applied and other devices behind it. Filters for SMB protocol packets using TCP ports 139 and 445 should also be deployed in front of vulnerable hosts so that traffic is allowed only from trusted clients.
Additional information about tACLs is available in "Transit Access Control Lists : Filtering at Your Edge": http://www.cisco.com/en/US/tech/tk648/tk361/technologies_white_paper09186a00801afc76.shtml.
Additional mitigation techniques that can be deployed on Cisco devices within the network are available in the Cisco Applied Mitigation Bulletin companion document for this advisory: http://www.cisco.com/warp/public/707/cisco-amb-20071205-csa.shtml.
Cisco Security Agent Rule to Block TCP Port 139 and 445 Traffic
Workstations that do not have a need to provide SMB services, such as services for sharing directories or files and printers, can be protected by configuring a Cisco Security Agent rule that blocks all traffic to TCP ports 139 and 445 (the SMB ports).
Such a rule exists in versions of Cisco Security Agent that include the Network Personal Firewall policy. The specific rule can be found by searching rules for one that has the description "All applications, server for SMB services (offering network shares)" or by opening the Personal Firewall Module rule module (attached to the Network Personal Firewall policy) and editing the rule that has this description. This rule is enabled by default but the default action must be changed from Allow to a High Priority Deny.
If the Network Personal Firewall policy is not available, administrators can create a network access rule that blocks traffic to TCP ports 139 and 445. To do this, the rule must be configured as a Deny rule so traffic is denied when the system on which Cisco Security Agent is installed attempts to act as a server for network services on ports TCP 139 and 445. For additional information on configuring Cisco Security Agent network access control rules, reference the following document:
Caution: Blocking TCP ports 139 and 445 on a Windows system will cause the Windows system to stop providing SMB services. Before implementing the workarounds presented in this section, administrators are advised to ensure that they understand the implications of disabling SMB services on users' workstations.