Cisco Unified Contact Center Enterprise Design Guide, Release 10.0(1)
Securing Unified CCE
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Securing Unified CCE

Securing Unified CCE

Introduction to Security

Achieving Unified CCE system security requires an effective security policy that accurately defines access, connection requirements, and systems management within your contact center. A good security policy enables you to use many state-of-the-art Cisco technologies to protect your data center resources from internal and external threats. Security measures ensure data privacy, integrity, and system availability.

The security considerations for Unified CCE at a high level are similar to the considerations for the other applications in a Cisco Unified Communications solution. Deployments of Unified CCE vary greatly and often call for complex network designs. These deployments require competence in Layer 2 and Layer 3 networking as well as voice, VPN, QoS, Microsoft Windows Active Directory, and other networking issues. This chapter provides some guidance that touches on these areas. But, this chapter is not an all-inclusive guide for deploying a secure Unified CCE network.

Along with the Unified Communications Security Solution portal, use other Cisco solution reference network design guides (SRNDs) in addition to this document to answer many design and deployment questions. These documents provide information on properly building a network infrastructure for Cisco Unified Communications. In particular, consult the following relevant documents about security and Cisco Unified Communications:
  • Cisco Unified Communications SRND Based on Cisco Unified Communications Manager
  • Data Center Networking: Server Farm Security SRNDv2
  • Site-to-Site IPSec VPN SRND
  • Voice and Video Enabled IPSec VPN (V3PN) SRND
  • Business Ready Teleworker SRND

Updates and additions to these documents are posted periodically, so visit the SRND web site frequently.

This chapter provides limited guidance on the intricacies of designing and deploying a Windows Active Directory. More information is available from Microsoft on the following topics:

  • Designing a new Active Directory logical structure

  • Deploying Active Directory for the first time

  • Upgrading an existing Windows environment to Microsoft Windows Server 2008 R2 Active Directory

  • Restructuring your current environment to a Windows Active Directory environment

In particular, see the Designing and Deploying Directory and Security Services section of the Microsoft Windows Server 2008 R2 Deployment Kit. That section can assist you in meeting all the Active Directory design and deployment goals for your organization. This development kit and its related documentation are available from Microsoft.

Security Layers

An adequately secure Unified CCE deployment requires a multilayered approach to protecting systems and networks from targeted attacks and the propagation of viruses, among other threats. The goal of this chapter is to stress the various areas pertinent to securing a Unified CCE deployment, but it does not delve into the details of each area. Specific details can be found in the relevant product documentation.

Implement the following security layers and establish policies around them:
  • Physical Security

    You must ensure that the servers hosting the Cisco contact center applications are physically secure. They must be located in data centers to which only authorized personnel have access. The cabling plant, routers, and switches also have controlled access. Implementing a strong physical-layer network security plan also includes utilizing such things as port security on data switches.

  • Perimeter Security

    While this document does not delve into the details on how to design and deploy a secure data network, it does provide references to resources that can aid in establishing an effective secure environment for your contact center applications.

  • Data Security

    To ensure an increased level of protection from eavesdropping for customer-sensitive information, Unified CCE provides support for Transport Layer Security (TLS) on the CTI OS and Cisco Agent Desktops. It also supports IPSec to secure communication channels between servers.

  • Host-Based Firewall

    You can use the Windows Firewall to protect from malicious users and programs that use unsolicited incoming traffic to attack servers. Use the Windows Firewall Configuration Utility on VMs or the Agent Desktop Installers to integrate with the firewall component of Windows Server 2008 R2.


    While Unified CCE does not support Windows XP, Cisco Finesse 10.0 does support Windows XP clients.

  • Virus Protection

    All VMs must be running antivirus applications with the latest virus definition files (scheduled for daily updates). The Compatibility Matrix for Unified CCE at http:/​/​​wiki/​Compatibility_​Matrix_​for_​Unified_​CCE contains a list of all the tested and supported antivirus applications.

  • Patch Management

    A system is typically not connected to a live network until all security updates have been applied. It is important for all hosts to be kept up-to-date with Microsoft (Windows, SQL Server, Internet Explorer, and so forth) and other third-party security patches.

For most of these security layers, the Unified CCE solution supports a number of capabilities. However, what Cisco cannot control or enforce is your enterprise policies and procedures for deploying and maintaining a secure Unified CCE solution.

Platform Differences

Before discussing how to design the various security layers required for a Unified CCE network, this section introduces the differences that are inherent in the applications making up the Unified CCE solution.

The Unified CCE solution consists of a number of application servers that are managed differently. The primary servers, those with the most focus in this document, are the Routers, Loggers (also known as Central Controllers), Peripheral Gateways, Administration & Data Servers, and so forth. These application servers can be installed only on a standard (default) operating system installation. For Unified CCE components that you install on Windows Server 2008 R2, use only a default retail version of the Windows Server software. The maintenance of this operating system in terms of device drivers, security updates, and so forth, is the responsibility of the customer, as is acquiring the necessary software from the appropriate vendors. This category of application servers is the primary focus of this topic.

The secondary group of servers, those running applications that are part of the solution but that are deployed differently, are Cisco Unified Communications Manager (Unified CM), Cisco Unified IP IVR, and so forth. Customers are required to obtain all relevant patches and updates to this operating system from Cisco. The security hardening specifications for this operating system can be found in the Cisco Collaboration System Solution Reference Network Designs and other Unified CM product documentation at http:/​/​​c/​en/​us/​support/​unified-communications/​unified-communications-manager-callmanager/​tsd-products-support-series-home.html.

The approach to securing the Unified CCE solution as it pertains to the various layers listed above differs from one group of servers to another. It is useful to keep this in mind as you design, deploy, and maintain these servers in your environment. Cisco is constantly enhancing its Unified Communications products with the eventual goal of having them all support the same customized operating system, antivirus applications, and security path management techniques.

Security Design Elements

Cisco has a security guide for the primary group of servers. The guide covers details of security implementation along with general guidance for securing a Unified CCE deployment. The security guide includes the following topics:
  • Encryption Support
  • IPSec and NAT Support
  • Windows Firewall Configuration
  • Automated Security Hardening
  • Updating Microsoft Windows
  • SQL Server Hardening
  • SSL Encryption
  • Microsoft Baseline Security Analysis
  • Auditing
  • Antivirus Guidelines
  • Secure Remote Administration

For a more in-depth discussion of security, see the Security Best Practices Guide for Cisco Unified ICM/Contact Center Enterprise & Hosted at http:/​/​​c/​en/​us/​support/​customer-collaboration/​unified-contact-center-enterprise/​products-configuration-examples-list.html.

The guidelines are based in part on hardening guidelines published by Microsoft and other third-party vendors. The guide also serves as a reference point for most of the security functionality in the product. The guide also covers installation for the Automated OS and SQL Security Hardening bundled with the application installer, Windows Firewall Configuration Utility, the SSL Configuration Utility, the Network Isolation IPSec Utility, and the Unified CC Security Wizard.

Other Security Guides

Other documents containing security guidance include, but are not limited to the following:

Table 1 Other Security Documentation

Security Topic

Document and URL

Server staging and Active Directory deployment

Staging Guide for Cisco Unified ICM/Contact Center Enterprise & Hosted at http:/​/​​c/​en/​us/​support/​customer-collaboration/​unified-contact-center-enterprise/​products-installation-guides-list.html

CTI OS encryption

CTI OS System Manager Guide for Cisco Unified ICM/Contact Center Enterprise & HostedCTI OS System Manager Guide for Cisco Unified ICM/Contact Center Enterprise & Hosted at http:/​/​​c/​en/​us/​support/​customer-collaboration/​unified-contact-center-enterprise/​products-installation-guides-list.html


Cisco CAD Installation Guide at http:/​/​​c/​en/​us/​support/​customer-collaboration/​agent-desktop/​products-installation-guides-list.html

SNMPv3 authentication and encryption

SNMP Guide for Cisco Unified ICM/Contact Center Enterprise & Hosted at http:/​/​​c/​en/​us/​support/​customer-collaboration/​unified-contact-center-enterprise/​products-configuration-examples-list.html

Unified ICM partitioning (Database object/access control)

Administration Guide for Cisco Unified Contact Center Enterprise & Hosted at http:/​/​​c/​en/​us/​support/​customer-collaboration/​unified-contact-center-enterprise/​products-maintenance-guides-list.html


Partitioning is supported only for Unified ICM Enterprise. It is not supported in Unified CCE, Unified ICM Hosted, or Unified Contact Center Hosted.

Feature Control (Software access control)

Configuration Guide for Cisco Unified ICM/Contact Center Enterprise & Hosted at http:/​/​​c/​en/​us/​support/​customer-collaboration/​unified-contact-center-enterprise/​products-configuration-examples-list.html

Validating real-time clients

Setup and Configuration Guide for Cisco Unified ICM Hosted at http:/​/​​c/​en/​us/​support/​customer-collaboration/​unified-contact-center-enterprise/​products-installation-guides-list.html

Network Firewalls

There are several important factors to consider when deploying firewalls in a Unified CCE network. The application servers making up a Unified CCE solution are not meant to reside in a demilitarized zone (DMZ) and must be segmented from any externally visible networks and internal corporate networks. The VMs must be placed in data centers, and the applicable firewalls or routers must be configured with access control lists (ACL) to control the traffic that is targeted to the VMs, thereby allowing only designated network traffic to pass through.

Deploying the application in an environment in which firewalls are in place requires the network administrator to be knowledgeable about which TCP/UDP IP ports are used, firewall deployment and topology considerations, and impact of Network Address Translation (NAT).

TCP/IP Ports

For an inventory of the ports used across the contact center suite of applications, see the following documentation:

To aid in firewall configuration, these guides list the protocols and ports used for agent desktop-to-server communication, application administration, and reporting. They also provide a listing of the ports used for intra-server communication.

Network Firewall Topology

The deployment shown in the section on AD Administrator created OUs represents the placement of firewalls and other network infrastructure components in a Unified CCE deployment. The design model incorporates a parent Unified ICM system with legacy peripheral hosts and a child Cisco Unified Contact Center Enterprise with a Unified CM cluster. For this deployment type, do the following:
  • Block the following ports at the enterprise perimeter firewall:
    • UDP ports 135, 137, 138, and 445
    • TCP ports 135, 139, 445, and 593
  • Deploy Layer-3 and Layer-4 ACLs that are configured as described in the port guides.
  • Isolate database and web services by installing dedicated historical data servers.
  • Minimize the number of Administration & Data Servers (ADS) and use Administration Clients (no database required) and internet script editor clients.
  • Use the same deployment guidelines when the parent Unified ICM or child Unified CCE central controllers are geographically distributed.
  • Deploy Windows IPSec (ESP) to encrypt intraserver communications.
  • Use Cisco IOS IPSec for site-to-site VPNs between geographically distributed sites, remote branch sites, or outsourced sites.

Network Address Translation

Network Address Translation (NAT) is a feature that resides on a network router and permits the use of private IP addressing. A private IP address is an IP address that cannot be routed on the Internet. When NAT is enabled, users on the private IP network can access devices on the public network through the NAT router.

When an IP packet reaches the NAT-enabled router, the router replaces the private IP address with a public IP address. For applications such as HTTP or Telnet, NAT does not cause problems. However, applications that exchange IP addresses in the payload of an IP packet experience problems because the IP address that is transmitted in the payload of the IP packet is not replaced. Only the IP address in the IP header is replaced.

To overcome this problem, Cisco IOS-based routers and PIX/ASA firewalls implement fix-ups for a variety of protocols and applications including SCCP and CTIQBE (TAPI/JTAPI). The fix-up allows the router to look at the entire packet and replace the necessary addresses when performing the NAT operation. For this process to work, the version of Cisco IOS or PIX/ASA must be compatible with the Unified CM version.

Unified CCE supports connectivity through a NAT except when CTI OS desktop monitoring/recording is in use. The IP address of the agent phone is seen as the NAT IP address, which causes the agent desktop to filter the IP packets improperly. For more information, consult the "IPSec and NAT Support" section of the Security Best Practices Guide for Cisco Unified ICM/Contact Center Enterprise & Hosted at http:/​/​​c/​en/​us/​support/​customer-collaboration/​unified-contact-center-enterprise/​products-configuration-examples-list.html.

Active Directory Deployment

This section describes the Active Directory and Firewall Deployment topology. For more detailed Active Directory (AD) deployment guidance, consult the Staging Guide for Cisco Unified ICM/Contact Center Enterprise & Hosted at http:/​/​​c/​en/​us/​support/​customer-collaboration/​unified-contact-center-enterprise/​products-installation-guides-list.html.

While Unified ICM and Unified CCE systems may still be deployed in a dedicated Windows Active Directory domain, it is not a requirement. What makes this possible is the capability of the software security principals to be installed in Organizational Units. This closer integration with AD and the power of security delegation means that corporate AD directories can be used to house application servers (for domain membership), user and service accounts, and groups.

Related Information

AD Site Topology

In a geographically distributed deployment of Unified ICM or Unified CCE, redundant domain controllers must be located at each of the sites, and properly configured Inter-Site Replication Connections must be established with a Global Catalog at each site. The Unified CCE application is designed to communicate with the AD servers that are in their site, but this requires an adequately implemented site topology in accordance with Microsoft guidelines.

Organizational Units

Application-Created OUs

The installation of Unified ICM or Unified CCE software requires that the AD Domain in which the VMs are members must be in Native Mode. The installation will add a number of OU objects, containers, users, and groups that are necessary for the operation of the software. Adding these objects can be done only in an Organizational Unit in AD over which the user running the install program has been delegated control. The OU can be located anywhere in the domain hierarchy, and the AD Administrator determines how deeply nested the Unified ICM/Unified CCE OU hierarchy is created and populated.


Local Server Accounts and groups are not created on the application servers. All created groups are Domain Local Security Groups, and all user accounts are domain accounts. The Service Logon domain account is added to the Local Administrators' group of the application servers.

Unified ICM and Unified CCE software installation is integrated with a Domain Manager tool that can be used standalone for pre-installing the OU hierarchies and objects required by the software, or can be used when the Setup program is invoked to create the same objects in AD. The AD/OU creation can be done on the domain in which the running VM is a member or on a trusted domain.

Do not confuse the creation of AD objects with Group Policy Objects (GPO). The Automated Security Hardening, which is provided and follows the standard Microsoft Security Template format, is not added to AD as part of the software installation through the configuration of a GPO. The security policy provided by this customized template (for Unified ICM/Unified CCE applications) is applied locally when a user chooses to apply hardening, or it can be pushed down through a GPO through manual AD configuration using the provided policy file, CiscoICM_Security_Template.inf.

AD Administrator-Created OUs

An administrator can create certain AD objects. A prime example is the OU container for Unified CCE Servers. This OU container is manually added to contain the VMs that are members of a given domain. You move these VMs to this OU once they are joined to the domain. This segregation controls who can or cannot administer the servers (delegation of control). Most importantly, the segregation controls the AD Domain Security Policies that the application servers in the OU can or cannot inherit.

As noted before, Unified ICM/Unified CCE servers ship with a customized security policy. You can apply this policy at this server OU level through a Group Policy Object (GPO). Block any differing policies from being inherited at the Unified ICM/Unified CCE Servers' OU. Remember that someone can override blocking inheritance, a configuration option at the OU object level, by selecting the Enforced/No Override option at a higher hierarchy level. The application of group policies must follow a well-planned design. Start with the most common denominator, and restrict those policies only at the appropriate level in the hierarchy. For a more in-depth explanation on how to deploy group policies properly, see the pages in the Microsoft Security Compliance Manager site at http:/​/​​en-us/​library/​cc677002.aspx.

Figure 1. Active Directory and Firewall Deployment Topology

The following notes apply to the preceding figure:
  • The application setup creates the Cisco_ICM organizational unit object hierarchies.
  • The AD administrators create Unified ICM Servers and Unified CCE Servers organizational unit objects to separately apply custom Cisco Unified ICM Security Policies through a GPO if necessary.
  • Flexible Single Master Operation servers must be distributed across Domain Controllers in the appropriate sites according to Microsoft guidelines.

IPsec Deployment

The Unified CCE solution relies on one or both of Microsoft Windows IPsec and Cisco IOS IPsec to secure critical links between VMs and sites. You can secure the solution in the following ways:

  • By deploying peer-to-peer IPsec tunnels between the VMs and sites

  • By deploying a more restrictive and preconfigured Network Isolation IPsec polic

  • y using a combination of both

The peer-to-peer IPsec deployment requires manual configuration for each communication path that must be secured, using the tools provided by Microsoft. However, you can automatically deploy the Network Isolation IPsec policy on each VM by using the Network Isolation IPsec utility. The utility secures all communication paths to or from that VM unless an exception is made. The Network Isolation IPsec utility is installed by default on all Unified CCE servers.

For more details, see the Security Best Practices Guide for Cisco Unified ICM/Contact Center Enterprise & Hosted at http:/​/​​c/​en/​us/​support/​customer-collaboration/​unified-contact-center-enterprise/​products-installation-and-configuration-guides-list.html.

This guide not only lists the supported paths, but also information to help users deploy Windows IPsec, including appropriate settings and much more.


Enabling IPsec affects scalability in several key areas.

Several connection paths in Unified CCE support IPsec. The following figure illustrates these guidelines. The figure shows the various server interconnections that must be secured with either Windows IPsec or Cisco IOS IPsec. The diagram also shows several paths that support TLS.

Figure 2. IPsec Deployment Example

Related Information

Host-Based Firewall

By providing host firewall protection on the innermost layer of your network, Windows Firewall can be an effective part of your defense-in-depth security strategy. Unified CCE supports the deployment of Windows Firewall on the VMs. The Security Best Practices Guide for Cisco Unified ICM/Contact Center Enterprise & Hosted contains a chapter on the implementation and configuration of this feature.

The configuration of the exceptions and the opening of the ports required by the application will still be done locally using the Windows Firewall Configuration Utility, which is included with the Unified CCE application.

The Windows Firewall is set up during Unified CCE installation, during which required ports are opened.

For more information about the Windows Firewall, see the Windows Firewall Operations Guide at http:/​/​​en-us/​library/​cc739696(v=WS.10).aspx.

Configuring Server Security

Unified Contact Center Security Wizard

The Unified Contact Center Security Wizard allows easy configuration of the security features defined above, namely, SQL Server Hardening, Windows Firewall configuration, and Network Isolation IPSec policy deployment. The Security Wizard encapsulates the functionality of these four utilities in an easy-to-use wizard-like interface that guides the user with the steps involved in configuring the security feature. (This is particularly helpful when deploying the Network Isolation IPSec policy.) The Security Wizard is installed by default with Unified CCE. The Security Best Practices Guide for Cisco Unified ICM/Contact Center Enterprise & Hosted at http:/​/​​c/​en/​us/​support/​customer-collaboration/​unified-contact-center-enterprise/​products-installation-and-configuration-guides-list.html contains a chapter explaining the Security Wizard in detail.

Virus Protection

Antivirus Applications

A number of third-party antivirus applications are supported for the Unified CCE system. For a list of applications and versions supported on your particular release of the Unified CCE software, see the Compatibility Matrix for Unified CCE at http:/​/​​wiki/​Compatibility_​Matrix_​for_​Unified_​CCE DocWiki and the Hardware and System Software Specification for Cisco Unified Customer Voice Portal (Unified CVP), as well as the Cisco Unified CCX and Unified Communications Manager product documentation for the applications supported. These documents are available on

Deploy only the supported applications for your environment, otherwise a software conflict might arise.

Configuration Guidelines

Antivirus applications have numerous configuration options that allow granular control of what and how data must be scanned on a VM.

With any antivirus product, configuration is a balance of scanning versus the performance of the VM. The more you choose to scan, the greater the potential performance overhead. The role of the system administrator is to determine what the optimal configuration requirements for installing an antivirus application within a particular environment. See the Security Best Practices Guide for Cisco Unified ICM/Contact Center Enterprise & Hosted at http:/​/​​c/​en/​us/​support/​customer-collaboration/​unified-contact-center-enterprise/​products-installation-and-configuration-guides-list.html and your particular antivirus product documentation for more detailed configuration information about a Unified ICM environment.

The following list highlights some general rules:
  • Upgrade to the latest supported version of the third-party antivirus application. Newer versions improve scanning speed over previous versions, resulting in lower overhead on VMs.
  • Avoid scanning of any files accessed from remote drives (such as network mappings or UNC connections). Where possible, each of these remote machines must have its own antivirus software installed, thus keeping all scanning local. With a multitiered antivirus strategy, scanning across the network and adding to the network load is not required generally.
  • Heuristics scanning has a higher overhead than traditional antivirus scanning. Use this advanced scanning option only at key points of data entry from untrusted networks (such as email and internet gateways).
  • You can enable real-time or on-access scanning, but only on incoming files (when writing to disk). This setting is the default for most antivirus applications. On-access scanning of file reads yields a higher than necessary impact on system resources in a high-performance application environment.
  • On-demand and real-time scanning of all files gives optimum protection. But, this configuration imposes the unnecessary overhead of scanning those files that cannot support malicious code (for example, ASCII text files). Exclude files or directories of files in all scanning modes that are known to present no risk to the system. Also, follow the guidelines for which specific Unified CCE files to exclude in Unified CCE implementation, as provided in the Security Best Practices Guide for Cisco Unified ICM/Contact Center Enterprise & Hosted .
  • Schedule regular disk scans only during low usage times and at times when application activity is lowest. To determine when application purge activity is scheduled, see the Security Best Practices Guide for Cisco Unified ICM/Contact Center Enterprise & Hosted listed in the previous item.

Intrusion Prevention

Cisco does not test or support intrusion prevention products by vendors such as Sygate, McAfee, and so on. Such products are capable of blocking legitimate application functionality if they incorrectly identify that application as a security threat. These products must be configured to allow legitimate operations to execute.

Patch Management

Security Patches

The security updates qualification process for Contact Center products is documented. This process applies to the VMs running the standard Windows Operating System.

Follow Microsoft guidelines regarding when and how to apply updates. All Contact Center customers must separately assess all security patches released by Microsoft and install those deemed appropriate for their environments.

Automated Patch Management

Unified CCE servers (except for the applications installed on VOS) support integration with Microsoft's Windows Server Update Services, whereby customers control which patches can be deployed to those VMs and when the patches can be deployed.

Selectively approve updates and determine when they get deployed on production VMs. The Windows Automatic Update Client (installed by default on all Windows hosts) can be configured to retrieve updates by polling a VM that is running Microsoft Window Update Services in place of the default Windows Update Web site.

For more configuration and deployment information, see theMicrosoft Deployment Guide and other step-by-step guides.

More information is also available on this topic in the Security Best Practices Guide for Cisco Unified ICM/Contact Center Enterprise & Hosted at http:/​/​​c/​en/​us/​support/​customer-collaboration/​unified-contact-center-enterprise/​products-configuration-examples-list.html.

The Cisco Unified Communications Operating System configuration and patch process does not currently allow for an automated patch management process.

Endpoint Security

Agent Desktops

The CTI OS (C++/COM toolkit) and CAD agent desktop servers both support TLS encryption to the server. This encryption protects agent login and CTI data from snooping. A mutual authentication mechanism enables the CTI OS Server and client to agree on a cipher suite for authentication, key exchange, and stream encryption. The cipher suite used is as follows:
  • Protocol: SSLv3
  • Key exchange: DH
  • Authentication: RSA
  • Encryption: AES (128)
  • Message digest algorithm: SHA1

The following figure shows the encryption implementation's use of X.509 certificates on the agent desktops as well as on the servers. The implementation supports the integration with a Public Key Infrastructure (PKI) for the most secure deployment. By default, the application installs and relies on a self-signed certificate authority (CA) to sign client and server requests. However, Cisco supports integration with a third-party CA. This mechanism is the preferred method because of the increased security provided by a corporate-managed CA or external authority such as Verisign.

Figure 3. Secure Agent Desktops (Certificate-Based Mutual Authentication)

The following figure shows the Certificate Authority enrollment procedure to generate certificates used by the agent and the servers. The agent desktop certificate enrollment process is manual. The process requires the creation of certificate signing requests (CSRs) at each endpoint. The CSRs are then transferred to the certificate authority responsible for signing and generating the certificates.

Figure 4. Certificate Authority Enrollment Procedure

Cisco Finesse supports HTTPS for the Administration Console and Agent and Supervisor Desktops. HTTPS is not supported for Agent and Supervisor Desktops in large deployments (over 1000 agents).

Unified IP Phone Device Authentication

When designing a Unified CCE solution based on Unified Communications Manager, customers may choose to implement device authentication for the Cisco Unified IP Phones. Unified CCE supports Unified Communications Manager’s Authenticated Device Security Mode, which ensures the following:
  • Device Identity — Mutual authentication using X.509 certificates
  • Signaling Integrity — SCCP/SIP messages authenticated using HMAC-SHA-1
  • Signaling Privacy — SCCP/SIP message content encrypted using AES-128-CBC

Media Encryption (SRTP) Considerations

Certain IP phones support Secure Real-Time Transport Protocol (SRTP). Before enabling SRTP in your deployment, consider the following points:

  • The Unified CVP VXML Browser does not support SRTP. While calls are connected to the VXML Browser, the calls cannot use SRTP. But, calls can negotiate SRTP once the media no longer terminates in the VXML Browser.

  • Deployments that use span-based silent monitoring do not support SRTP.

  • Mobile Agents cannot use SRTP.

  • The Cisco Outbound Option Dialers do not support SRTP. While calls are connected to the Dialer, the calls cannot use SRTP. But, calls can negotiate SRTP once the call is no longer connected to the Dialer.

IP Phone Hardening

The IP phone device configuration in Unified CM provides the ability to disable a number of phone features to harden the phones, such as disabling the phone's PC port or restricting a PC from accessing the voice VLAN. Changing some of these settings can disable the monitoring/recording feature of the Unified CCE solution. The settings are defined as follows:
  • PC Voice VLAN Access
    • Indicates whether the phone will allow a device attached to the PC port to access the Voice VLAN. Disabling Voice VLAN Access will prevent the attached PC from sending and receiving data on the Voice VLAN. It will also prevent the PC from receiving data sent and received by the phone. Disabling this feature will disable desktop-based monitoring and recording.
    • Setting: Enabled (default)
  • Span to PC Port
    • Indicates whether the phone will forward packets transmitted and received on the Phone Port to the PC Port. To use this feature, PC Voice VLAN access must be enabled. Disabling this feature will disable desktop-based monitoring and recording.
    • Setting: Enabled
Disable the following setting to prevent man-in-the-middle (MITM) attacks unless the third-party monitoring and/or recording application deployed uses this mechanism for capturing voice streams. The CTI OS Silent Monitoring feature and CAD Silent Monitoring and Recording do not depend on Gratuitous ARP.
  • Gratuitous ARP
    • Indicates whether the phone will learn MAC addresses from Gratuitous ARP responses.
    • Setting: Disabled