1. Network security policy: best practices
Ref: document ID 13601

2. Process Preparation Prevention Response Create usage policy statement
Conduct a risk analysis
Establish a security team structure
Prevention
Approving security changes
Monitoring security of your network
Response
Security violation
Restoration
Review

3. Preparation: Create usage policy statement (1)
Outline user’s roles and responsibilities with regard to security
General policy : cover all network system and data within your company, by providing :
Understanding of the security policy, its purpose
Guidelines for improving their security practices
Definitions of their security responsibilities
Identify specific action that could result in punitive

4. Preparation: Create usage policy statement (2)
Partner acceptable use statement : it provides
Partner with an understanding of the information that is available to them
The expected disposition of that information
The conduct of the employee of your company
Clearly explain any specific acts that have been identified as security attacks and the punitive action

5. Preparation: Create usage policy statement (3)
Administrator acceptable use statement: to explain
The procedures for user account administration
Policy enforcement
Privilege review
It should be clearly presented specific policies concerning user passwords and handling data
Check the policy with the partner acceptable use and user acceptable use statement to ensure uniformity
Make sure that admin requirement listed in policy are reflected in training plan and performance evaluation

6. Preparation: Conduct a risk analysis (1)
A risk analysis should identify the risk to
Network , resources and data
To identify portion of your network, assign a threat rating to each portion and apply appropriate level of security
Each network resources can be assigned as 3 risk level
Low risk:
system or data that if compromised would not disrupt the business or cause legal or financial ramification, not provide further access to other system
The targeted system or data can be easily restored
Medium risk
system or data that if compromised would cause a moderate disruption in the business or minor legal or financial ramification, provide further access to other system
The targeted system or data requires a moderate effort to restore
The restoration process is disruptive to the system

7. Preparation: Conduct a risk analysis (2)
High risk
system or data that if compromised would cause an extreme disruption in the business or major legal or financial ramification,
Threaten the health and safety of a person
provide further access to other system
The targeted system or data requires a significant effort to restore
The restoration process is disruptive to the business or the other systems

8. Preparation: Conduct a risk analysis (3)
Identify the type of users as 5 most common types:
Administrators : internal users responsible for network resources
Privileged: internal users with a need for greater access
Users: internal users with a general access
Partners: external users with a need to access some resources
Others: external users or customer

10. Preparation: Establish team structure
Create a cross functional security led by a Security Manager with participants from each of your company’s operational area
The security team has 3 areas of responsibilities
Policy development : establishing and reviewing security policies for the company
Practice: conduct the risk analysis, the approval of security change requests, review security alerts from both vendor and the CERT (Community Emergency Response Team) and turn the policy to implementations
Response: to do the troubleshooting and fixing of such a violation, each team member should know in detail the security features provided by the equipment

11. Prevention: Approving security changes (1)
Recommendation on reviewing the following types of changes:
Any changes to the firewall configuration
Any change to access control list (ACL)
Any change to Simple Network Management Protocol (SNMP) configuration
Any change or update in software that differs from the approved software revision level list

12. Prevention: Approving security changes (2)
Recommended guidelines
Change passwords to network devices on a routine basis
Restrict access to network devices to an approved list of personnel
Ensure that the current software revision levels of network equipment and server environments are in compliance with the security configuration requirement

13. Prevention: Monitoring security of your network (1)
Similar to network monitoring except it focuses on detecting changes in the network that indicating a security violation
In the Risk analysis matrix
the firewall is considered as high risk network device – monitor it in real time
From the Approving security changes
Any changes to the firewall should be monitored
It means SNMP agent should monitor such things as failed login attempts, unusual traffic, changes to the firewall, access granted to the firewall and connection set up through the firewall

14. Prevention: Monitoring security of your network (2)
Following this example, create a monitoring policy for each area identified in your risk analysis
Low-risk equipment : monitoring weekly
Medium-risk equipment : monitoring daily
High-risk equipment : monitoring hourly
Lastly, security policy should address how to notify the security team of security violations such as , SMS

15. Response: Security violation (1)
First action after detection of an intrusion is the notification of the security team
Define a procedure in security policy that is available 24 hours a day, 7 days a week
Next define the level of the authority given to the security team to make changes, possible corrective actions are
Implementing changes to prevent further access to the violation
Isolating the violated systems
Contacting the carrier or ISP in an attempt to trace the attack

16. Response: Security violation (2)
Using recording devices to gather evidence
Disconnecting violated systems or the source of the violation
Contacting the police or other government agencies
Shutting down violated system
Restoring system according to a prioritized list
Notify internal managerial and legal personnel

17. Response: Security violation (3)
Lastly, collecting and maintaining information during security attack
To determine the extent to which systems have been compromised
To prosecute external violations
To determine the extent of the violation
Record the event by obtaining sniffer traces of the network, copies of log files, active user accounts and network connections
Limit further compromise by disabling account, disconnecting the network equipment from the network and disconnecting from the internet

18. Response: Security violation (4)
Back up the compromised system to aid in a detailed analysis of the damage and method of attack
Look for other signs of compromise.
Often when system is compromised there are other systems or accounts involved
Maintain and review security device log files and network monitoring log files and the often provide clues to the method of attack

19. Response: Restoration
Define in the security policy how to conduct secure and make available normal backup
As each system has its own means and procedures for backing up the security policy should act as a meta-policy
detailing for each system security condition that require restoration from backup
If approval is required before restoration can be done include the process for obtaining approval as well

20. Response: Review (1)
It is the final effort in creating and maintaining a security policy
3 things to be reviewed
Policy / Posture / Practice
Security policy should be a living document
Reviewing against known best practices
Check the CERT website for useful tips, practices security improvement and alert

21. Response: Review (2)
Review network posture in comparison with the desired security posture
Outside firm that specializes in security can attempt to penetrate the network and test not only the posture of the network but the security response of organization as well
For high-availability networks, recommend conducting such a test annually
Finally, practice is defined as a test of the support staff to insure that they have clear understanding of what to do during a security violation
Often the test is unannounced and done conjunction with the network posture test
It show the gaps in procedure and training of personnel so that corrective action can be taken