The IP phone contains key information about the IP addresses of the Cisco CallManager, network gateway, TFTP server, and DNS servers. Obtaining this information allows a hacker to map out the location of key network resources.
Only Cisco's flagship phones, the 7940, 7960, and 7970, support configuration file authentication. The 7920 wireless handset does not support this feature.
You can find all the security settings for an IP phone under the Phone Configuration window in the Cisco CallManager administration utility.
To access the built-in web server of an IP phone, simply access the URL http://IP-Phone's-IP-address. There are no security options; you will be directed to a page giving all the information about the IP phone's network settings.
Gratuitous ARP attackers always operate from the local network. This is necessary due to the nature of ARP packets.
Even with authentication and encryption features enabled, SCCP maintains its signaling role. There are no currently known attacks against Skinny signaling, so there was no reason to secure it further.
An IP phone can provide all the preceding information with the exception of the intranet server address.
Cisco CallManager does not allow you to disable the PC port of the 7912 IP Phone. Filling the PC port of the phone with glue (or some similarly drastic step), or downgrading to the 7905 IP Phone is the best step for now.
Secure Sockets Layer (SSL) was the predecessor to Transport Layer Security (TLS). SSL was primarily applied to HTTPS connections, whereas TLS became more universally used.
Since Cisco CallManager 3.3(3), the signed firmware validation feature is already enabled. This prevents hackers from constructing their own, rogue firmware images for the Cisco IP Phones.
Part I: Cisco CallManager Fundamentals
Introduction to Cisco Unified Communications and Cisco Unified CallManager
Cisco Unified CallManager Clustering and Deployment Options
Cisco Unified CallManager Installation and Upgrades
Part II: IPT Devices and Users
Cisco IP Phones and Other User Devices
Configuring Cisco Unified CallManager to Support IP Phones
Cisco IP Telephony Users
Cisco Bulk Administration Tool
Part III: IPT Network Integration and Route Plan
Cisco Catalyst Switches
Configuring Cisco Gateways and Trunks
Cisco Unified CallManager Route Plan Basics
Cisco Unified CallManager Advanced Route Plans
Configuring Hunt Groups and Call Coverage
Implementing Telephony Call Restrictions and Control
Implementing Multiple-Site Deployments
Part IV: VoIP Features
Configuring User Features, Part 1
Configuring User Features, Part 2
Configuring Cisco Unified CallManager Attendant Console
Configuring Cisco IP Manager Assistant
Part V: IPT Security
Securing the Windows Operating System
Securing Cisco Unified CallManager Administration
Preventing Toll Fraud
Hardening the IP Phone
Understanding Cryptographic Fundamentals
Understanding the Public Key Infrastructure
Understanding Cisco IP Telephony Authentication and Encryption Fundamentals
Configuring Cisco IP Telephony Authentication and Encryption
Part VI: IP Video
Introducing IP Video Telephony
Configuring Cisco VT Advantage
Part VII: IPT Management
Introducing Database Tools and Cisco Unified CallManager Serviceability
Configuring Alarms and Traces
Using Additional Management and Monitoring Tools
Part VIII: Appendix
Appendix A. Answers to Review Questions