Network Security Policies

Network security policy

A security policy defines rules for protecting information, systems, and services. The rules set expectations for users, administrators, and system components, and assign responsibility for security decisions. The document states security objectives and constraints while procedures and technical standards describe implementation details.

covers how the network is used, managed, and protected. Examples of violations include exposing sensitive data, installing unapproved software, or connecting a device with a configuration that bypasses required controls. Standards, procedures, and technical controls are derived from the policy.

The document should identify an owner, scope, version, approval date, exceptions, and measures for checking implementation. The owner updates the policy after changes to services, technology, law, or risk. Approved exceptions have an expiry date and a documented justification.

Security policy objectives

A policy organizes requirements for confidentiality, integrity, and availability. It also assigns responsibility for configuration, training, incident response, and evidence of control operation.

Confidentiality: limiting disclosure. The policy classifies sensitive information and identifies the roles or people allowed to receive, process, and share it. Access is granted for a documented business need.
Integrity: protecting against change. The policy defines who can modify or delete data, how changes are reviewed, and how unauthorized activity is detected. Audit records help identify the account and time associated with an operation.
Availability: maintaining services. The policy sets requirements for redundancy, backups, recovery, and protection against attacks such as Distributed Denial of Service (DDoS). The required availability level follows service needs and risk assessment.
Establishing a standard: The policy gives teams a common baseline for system configuration, equipment deployment, and training. The baseline can be translated into requirements for devices, accounts, applications, and processes.
Demonstrating due diligence and compliance: Written rules document how an organization protects systems and data. Depending on its activities, the organization may have requirements from the Health Insurance Portability and Accountability Act (HIPAA), the Payment Card Industry Data Security Standard (PCI DSS), or the Sarbanes-Oxley Act (SOX). The documentation lets auditors compare requirements with configuration and operational practice.

Security policy framework components

A network security policy may be one document or a set of related policies, standards, and guidelines. Each document covers an area such as access, passwords, remote access, incident response, or data classification. The scope depends on risk, organizational size, and legal or contractual requirements.

1. Acceptable Use Policy (AUP)

The AUP describes how employees, contractors, and guests may use company IT resources. It states permitted uses, prohibited activities, and the channel for reporting violations.

An AUP typically covers:

Use and ownership: State the intended business use of company systems and the scope of monitoring.
Privacy: Inform users about monitoring rules for company equipment and accounts.
Prohibited activities: Prohibit illegal activity, unauthorized access attempts, unapproved software, password sharing, and peer-to-peer file-sharing applications.
Information protection: Assign responsibilities for sensitive company data and its disclosure.
Consequences of violation: Describe disciplinary actions, from a warning to termination, in accordance with employment rules and law.

2. Access Control Policy

This policy formalizes . It identifies subjects, resources, operations, and conditions used to grant access.

An access control policy should:

Define roles and responsibilities: Group users by job function, such as Finance, Human Resources, and Engineering.
Map roles to resources: Specify the servers, applications, and data available to each role. The Finance role can include the accounting server, while the source code repository remains assigned to Engineering.
Specify access levels: Distinguish read, write, and administrative permissions.
Require authentication: Protect restricted resources with authentication and use multi-factor authentication (MFA) for higher-risk operations.

The access process should cover joining, role changes, and departure. Service accounts need an owner, a limited scope, and periodic review. Access recertification and recorded decisions help identify permissions that are no longer required.

3. Password Policy

A password policy defines length, treatment of compromised passwords, and limits on login attempts. NIST SP 800-63B-4 sets minimum lengths, requires a blocklist of common, expected, or compromised values, and does not permit arbitrary composition rules.

Length and passphrases: If a policy states a threshold such as $14$ characters, it should be compared with current requirements. NIST SP 800-63B-4 requires at least 15 characters for a password used as a single factor and at least 8 characters when used with MFA. The system should permit a maximum length of at least 64 characters.
Password history: A policy may prevent reuse of the last $24$ passwords. The check should also cover common and compromised passwords.
Password changes: A 90-day change interval can reflect a local requirement, while NIST SP 800-63B-4 does not permit forced periodic changes and requires a change after compromise is detected. Regular changes alone do not replace breach monitoring.
Attempt limits: A policy may use a limit, delay, or lockout after 5 failed attempts. The mechanism should limit guessing while reducing the risk of third-party account lockout.

4. Remote Access Policy

This policy describes access to organizational resources from outside a managed network. Controls should account for the user identity, device state, connection method, and requested resource.

Approved methods: Specify whether access uses the corporate Virtual Private Network (VPN), an application portal, or another controlled connection.
Authentication: Require multi-factor authentication for connections and higher-risk operations.
Endpoint compliance: Require a managed or compliant device with current patches, endpoint protection, and the configuration defined by the organization.

5. Incident Response Policy

The policy defines preparation, detection, analysis, containment, eradication, recovery, and lessons learned after an incident. The Incident Response (IR) plan assigns authority and responsibility to an Incident Response Team (IRT), records contacts, and states notification requirements. NIST SP 800-61 Rev. 3 connects incident response with enterprise risk management and the six functions of CSF 2.0.

6. Data Classification Policy

The policy classifies data according to the consequences of losing confidentiality, integrity, or availability. Classification follows risk, context, and legal or operational requirements. An example scheme includes:

Public: Information intended for publication, such as marketing materials on the website.
Internal: Data for organizational use where disclosure has a limited effect, such as internal memos.
Confidential: Business or employee data where disclosure has a material effect. It requires access controls and encryption, such as for business plans and employee data.
Restricted: Trade secrets, financial records, and Personally Identifiable Information (PII), such as Social Security Numbers, where disclosure can have a severe effect. The risk assessment sets the required security controls.

Handling procedures define labeling, storage, transmission, sharing, and disposal for each class. Protected data may require encryption, key management, limits on copies, and confirmation of secure destruction after the retention period.

Security policy lifecycle

A policy requires an owner, approval, implementation, monitoring, and review. Its lifecycle connects the document with technical controls and user practice.

The owner defines measures such as the timeliness of access reviews, the proportion of devices meeting the baseline, and the time needed to handle exceptions. Management reviews the results with risks, an action plan, and the next assessment date.

Development and approval: Security, IT, and business representatives define the need, scope, and risks. The draft records its owner, audience, requirements, and measurement method. Management approves the document and assigns its effective version.
Implementation and enforcement: The rules are translated into technical controls and procedures. Password rules can be configured in Microsoft Active Directory, while access rules are implemented in firewalls and router ACLs. The owner handles exceptions and records their approval.
Communication, training, and awareness: Users receive the AUP, reporting channel, and examples of expected behavior. Training explains the requirements and the threats they address, and completion can be recorded.
Monitoring and auditing: Logs, configuration scans, and access reviews provide evidence of compliance. Internal and external audits compare technical controls and user practices with the document requirements.
Review and update: Reviews consider changes in technology, processes, and threats. A policy written two years ago may require correction, so the organization sets a risk-based review interval, for example once a year, and reviews the document after a material incident or system change.

Connecting policies to compliance frameworks

A policy translates legal, industry, and organizational requirements into rules and evidence of implementation. Compliance frameworks organize controls, while their scope and status depend on the organization's activities.

Examples include:

ISO/IEC 27001: A standard for an information security management system. It sets requirements for an ISMS, including risk management, objectives, responsibilities, and improvement. It leaves the choice of tools and control implementation to the organization.
PCI DSS: A standard for entities that store, process, or transmit cardholder data. Its controls cover access, authentication, event logging, and segmentation. The organization documents how it meets the requirements in policies and procedures.
HIPAA: A US framework for protecting protected health information (PHI) that applies to covered entities and business associates. Its Security Rule addresses administrative, physical, and technical safeguards; applicable organizations document how those safeguards are implemented.

During an audit, reviewers examine policies, technical configurations, and operational procedures. They compare requirements with evidence that controls operate, such as settings, logs, reviews, and training records. Missing documentation or evidence can result in a finding.

The policy should distinguish mandatory requirements, recommendations, and decisions based on risk assessment. This distinction supports control planning and the review of exceptions.