https://www.sans.org/white-papers/38945
This paper examines the vulnerabilities of VoWiFi calling, assesses what common and less well-known attacks are able to exploit those vulnerabilities, and then proposes technological or procedural security protocols to harden telephony systems against adversary exploitation.
https://www.sans.org/white-papers/1701
This paper focuses on these VoIP specific security threats and the countermeasures to mitigate the problem.
https://www.sans.org/white-papers/35817
This SANS whitepaper discusses the need for web application firewalls.
https://securityboulevard.com/2019/12/endpoints-and-network-segmentation-best-practices/
This article speaks to the deficiencies in current network segmentation for the endpoint and network segmentation best practices.
https://www.infosecinstitute.com/resources/securityplus/security-implementing-a-public-key-infrastructure/
This article describes the basic concepts and components of Public Key Infrastructure (PKI)
https://txwes.edu/media/twu/content-assets/documents/it/policyprocedures/firewall-policy.pdf
This sample policy defines the essential rules regarding the management and maintenance of firewalls at Texas Wesleyan.
TMC Net – VoIP Security Monitoring and Management; What Every Security Professional Needs to Know
3.13 3.13.14 System and Communications Protection
https://www.tmcnet.com/voip/1107/feature-articles-voip-security-monitoring-and-management-what-every-security-professional-needs-to-know.htm
This article focuses on key aspects of VoIP security monitoring and management.
https://help.deepsecurity.trendmicro.com/20_0/on-premise/firewall-actions-priorities.html
Trend Micro’s Deep Security Help Center
https://www.trustradius.com/categories/web-content-filtering
This site provides a listing of Web Content Filtering solutions. WCF solutions comprise appliances and software for censoring or preventing access to restricted web content deemed offensive or inappropriate.
https://security.berkeley.edu/secure-device-configuration-guideline
This is UC Berkeley's secure device configuration guideline with adherence to their security policy mandate. This is an example of a how to assess a secure configuration.