Hi Gautam,
Here are a couple of reference documents for CUCM that may be useful. There isn't anything to install further on the CUCM server itself as it is an appliance. There are, however, recommendations for different configurations and features that may be employed to secure the voice network.
1. Security Chapter of the SRND:
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/srnd/6x/security.html#wp1046276
* Cisco Unified CM 6.x currently does not support managed Cisco Security Agent capability.
* Cisco Unified CM 6.x currently does not support the use of antivirus software.
2. CUCM Security Guide
http://www.cisco.com/en/US/docs/voice_ip_comm/cucm/security/6_0_1/secugd/secuview.html
Hope this helps.
Regards,
Michael.