I co-authored a book in 2005, titled "Extreme Exploits: Advanced Defenses Against Hardcore Hacks." My chapters focused on securing routing protocols such as BGP, and securing systems related to DMZs, firewalls, and network connectivity.
As I look back over those chapters, I realize that the basic fundamentals of network security really haven't changed much even though technology has advanced at an incredible pace. "Defense in depth" was a hot catch phrase seven years ago, and it still applies today. I believe there are three broad steps any organization can take with respect to security and reliability to get a handle on their current security posture, whether internal (corporate, inside the firewall) or external (Internet, outside the firewall).
Begin with a "network assessment." This is a broad term that might encompass a holistic view of an organization's Internet security posture, including Internet gateways, firewalls, DNS and email services, and B2B partner connectivity. In addition or alternatively, a network assessment may focus on an organization's internal network, including employee intranets, VPN, electronic mail, DNS, VoIP, vulnerability management and anti-virus services, change management, and business continuity planning and disaster recovery. A network assessment can be tailored to specific security requirements for any organization, but ultimately the assessment will provide a baseline gap analysis and remediation steps to fill those gaps.
Once a baseline network assessment is completed, an organization may wish to perform periodic vulnerability assessments. Traditional vulnerability assessments tend to cover applications services and nothing more. However, an organization's security posture must include Internet gateway switches/routers, firewalls, DNS servers, mail servers, and other network infrastructure not directly related to providing service for a specific application. Whether internal or external, vulnerability assessments can uncover critical gaps in security that may lead to credential leaks, intellectual property theft, or denial of service to employees or customers. A well planned and executed vulnerability assessment should eliminate false positives, but can never give an organization 100% confidence that a specific vulnerability can be exploited. Vulnerability assessments should be executed on at least a quarterly basis, but it's not uncommon for larger organizations to execute them on a monthly basis.
The next step in assessing your organization's security and reliability is penetration testing. While I typically say that vulnerability assessments give you a "95% confidence level" that a vulnerability exists, penetration testing can give you 100% confidence that a specific vulnerability can be exploited and show you how it can be exploited by attackers. Alternatively, a penetration test may show you that you have proper compensating controls in place to prevent a vulnerability from being exploited. That is to say, the vulnerability exists, but a compensating control is in place that prevents attackers from succeeding.
One only needs to read the news to know that every organization, whether large or small, is susceptible to intrusions across their networks or exploits in their applications and services. It's prudent to execute a network assessment in order to understand your current security posture, and then follow up with periodic vulnerability assessments and penetration tests. These will give you a higher level of confidence that your architecture is sound, and that your staff is adhering to security policies and procedures. Ultimately, your customers trust you to secure your resources and their information, and your brand and market identity are at stake if you don't.
By Brett Watson, Senior Manager, Professional Services at Neustar. Brett's experience spans large-scale IP networking, optical networking, network/system administration and design, and security architecture including high level security policy and architecture, as well as vulnerability assessments and penetration testing.
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