4.3. VNF Security¶
The objective of this section is to provide the key security requirements that need to be met by VNFs. The security requirements are grouped into five areas as listed below. Other security areas will be addressed in future updates. These security requirements are applicable to all VNFs. Additional security requirements for specific types of VNFs will be applicable and are outside the scope of these general requirements.
Section 4.3 Security in VNF Guidelines outlines the five broad security areas for VNFs that are detailed in the following sections:
- VNF General Security: This section addresses general security requirements for the VNFs that the VNF provider will need to address.
- VNF Identity and Access Management: This section addresses security requirements with respect to Identity and Access Management as these pertain to generic VNFs.
- VNF API Security: This section addresses the generic security requirements associated with APIs. These requirements are applicable to those VNFs that use standard APIs for communication and data exchange.
- VNF Security Analytics: This section addresses the security requirements associated with analytics for VNFs that deal with monitoring, data collection and analysis.
- VNF Data Protection: This section addresses the security requirements associated with data protection.
4.3.1. VNF General Security Requirements¶
This section provides details on the VNF general security requirements on various security areas such as user access control, network security, ACLs, infrastructure security, and vulnerability management. These requirements cover topics associated with compliance, security patching, logging/accounting, authentication, encryption, role-based access control, least privilege access/authorization. The following security requirements need to be met by the solution in a virtual environment:
General Security Requirements
Integration and operation within a robust security environment is necessary and expected. The security architecture will include one or more of the following: IDAM (Identity and Access Management) for all system and applications access, Code scanning, network vulnerability scans, OS, Database and application patching, malware detection and cleaning, DDOS prevention, network security gateways (internal and external) operating at various layers, host and application based tools for security compliance validation, aggressive security patch application, tightly controlled software distribution and change control processes and other state of the art security solutions. The VNF is expected to function reliably within such an environment and the developer is expected to understand and accommodate such controls and can expected to supply responsive interoperability support and testing throughout the product’s lifecycle.
The VNF MUST implement and enforce the principle of least privilege on all protected interfaces.
The VNF MUST provide a mechanism (e.g., access control list) to permit and/or restrict access to services on the VNF by source, destination, protocol, and/or port.
The VNF SHOULD provide a mechanism that enables the operators to perform automated system configuration auditing at configurable time intervals.
The VNF SHOULD provide the capability for the Operator to run security vulnerability scans of the operating system and all application layers.
The VNF SHOULD have source code scanned using scanning tools (e.g., Fortify) and provide reports.
The VNF MUST have all code (e.g., QCOW2) and configuration files (e.g., HEAT template, Ansible playbook, script) hardened, or with documented recommended configurations for hardening and interfaces that allow the Operator to harden the VNF. Actions taken to harden a system include disabling all unnecessary services, and changing default values such as default credentials and community strings.
The VNF SHOULD support network segregation, i.e., separation of OA&M traffic from signaling and payload traffic, using technologies such as VPN and VLAN.
The VNF SHOULD support the use of virtual trusted platform module.
The VNF MUST interoperate with the ONAP (SDN) Controller so that it can dynamically modify the firewall rules, ACL rules, QoS rules, virtual routing and forwarding rules.
The VNF Provider MUST have patches available for vulnerabilities in the VNF as soon as possible. Patching shall be controlled via change control process with vulnerabilities disclosed along with mitigation recommendations.
The VNF MUST support encrypted access protocols, e.g., TLS, SSH, SFTP.
The VNF MUST store Authentication Credentials used to authenticate to other systems encrypted except where there is a technical need to store the password unencrypted in which case it must be protected using other security techniques that include the use of file and directory permissions. Ideally, credentials SHOULD rely on a HW Root of Trust, such as a TPM or HSM.
For all GUI and command-line interfaces, the VNF MUST provide the ability to present a warning notice that is set by the Operator. A warning notice is a formal statement of resource intent presented to everyone who accesses the system.
The VNF MUST allow the Operator to disable or remove any security testing tools or programs included in the VNF, e.g., password cracker, port scanner.
The VNF MUST provide functionality that enables the Operator to comply with requests for information from law enforcement and government agencies.
The VNF MUST support the ability to prohibit remote access to the VNF via a host based security mechanism.
The VNF MUST log any security event required by the VNF Requirements to Syslog using LOG_AUTHPRIV for any event that would contain sensitive information and LOG_AUTH for all other relevant events.
The VNF MUST be operable without the use of Network File System (NFS).
The VNF MUST NOT contain any backdoors.
If SNMP is utilized, the VNF MUST support at least SNMPv3 with message authentication.
The VNF application processes MUST NOT run as root.
Login access (e.g., shell access) to the operating system layer, whether interactive or as part of an automated process, MUST be through an encrypted protocol such as SSH or TLS.
The VNF MUST, after a successful login at command line or a GUI, display the last valid login date and time and the number of unsuccessful attempts since then made with that user’s ID. This requirement is only applicable when the user account is defined locally in the VNF.
The VNF MUST include a configuration, e.g., a heat template or CSAR package, that specifies the targetted parameters, e.g. a limited set of ports, over which the VNF will communicate (including internal, external and management communication).
4.3.2. VNF Identity and Access Management Requirements¶
The following security requirements for logging, identity, and access management need to be met by the solution in a virtual environment:
Identity and Access Management Requirements
The VNF MUST, if not integrated with the Operator’s Identity and Access Management system, support the creation of multiple IDs so that individual accountability can be supported.
The VNF MUST allow the Operator to restrict access based on the assigned permissions associated with an ID in order to support Least Privilege (no more privilege than required to perform job functions).
Each architectural layer of the VNF (eg. operating system, network, application) MUST support access restriction independently of all other layers so that Segregation of Duties can be implemented.
The VNF MUST NOT allow the assumption of the permissions of another account to mask individual accountability. For example, use SUDO when a user requires elevated permissions such as root or admin.
The VNF MUST set the default settings for user access to deny authorization, except for a super user type of account. When a VNF is added to the network, nothing should be able to use it until the super user configures the VNF to allow other users (human and application) have access.
The VNF MUST support strong authentication, also known as multifactor authentication, on all protected interfaces exposed by the VNF for use by human users. Strong authentication uses at least two of the three different types of authentication factors in order to prove the claimed identity of a user.
The VNF MUST disable unnecessary or vulnerable cgi-bin programs.
The VNF MUST provide access controls that allow the Operator to restrict access to VNF functions and data to authorized entities.
The VNF SHOULD support OAuth 2.0 authorization using an external Authorization Server.
The VNF MUST, if not integrated with the Operator’s Identity and Access Management system, support configurable password expiration.
The VNF MUST, if not integrated with the Operator’s Identity and Access Management system, support Role-Based Access Control to enforce least privilege.
The VNF MUST, if not integrated with the Operator’s Identity and Access Management system, comply with “password complexity” policy. When passwords are used, they shall be complex and shall at least meet the following password construction requirements: (1) be a minimum configurable number of characters in length, (2) include 3 of the 4 following types of characters: upper-case alphabetic, lower-case alphabetic, numeric, and special, (3) not be the same as the UserID with which they are associated or other common strings as specified by the environment, (4) not contain repeating or sequential characters or numbers, (5) not to use special characters that may have command functions, and (6) new passwords must not contain sequences of three or more characters from the previous password.
The VNF MUST not store authentication credentials to itself in clear text or any reversible form and must use salting.
The VNF MUST, if not integrated with the Operator’s Identity and Access Management system, support the ability to disable the userID after a configurable number of consecutive unsuccessful authentication attempts using the same userID.
The VNF MUST, if not integrated with the Operator’s identity and access management system, authenticate all access to protected GUIs, CLIs, and APIs.
The VNF MUST integrate with standard identity and access management protocols such as LDAP, TACACS+, Windows Integrated Authentication (Kerberos), SAML federation, or OAuth 2.0.
The VNF MUST have the capability of allowing the Operator to create, manage, and automatically provision user accounts using an Operator approved identity lifecycle management tool using a standard protocol, e.g., NETCONF API.
The VNF MUST support account names that contain at least A-Z, a-z, 0-9 character sets and be at least 6 characters in length.
A failed authentication attempt MUST NOT identify the reason for the failure to the user, only that the authentication failed.
The VNF MUST NOT display “Welcome” notices or messages that could be misinterpreted as extending an invitation to unauthorized users.
The VNF MUST provide a means for the user to explicitly logout, thus ending that session for that authenticated user.
The VNF MUST, if not integrated with the Operator’s Identity and Access Management system, or enforce a configurable “terminate idle sessions” policy by terminating the session after a configurable period of inactivity.
4.3.3. VNF API Security Requirements¶
This section covers API security requirements when these are used by the VNFs. Key security areas covered in API security are Access Control, Authentication, Passwords, PKI Authentication Alarming, Anomaly Detection, Lawful Intercept, Monitoring and Logging, Input Validation, Cryptography, Business continuity, Biometric Authentication, Identification, Confidentiality and Integrity, and Denial of Service.
The solution in a virtual environment needs to meet the following API security requirements:
The VNF SHOULD integrate with the Operator’s authentication and authorization services (e.g., IDAM).
The VNF MUST implement the following input validation control: Check the size (length) of all input. Do not permit an amount of input so great that it would cause the VNF to fail. Where the input may be a file, the VNF API must enforce a size limit.
The VNF MUST implement the following input validation controls: Do not permit input that contains content or characters inappropriate to the input expected by the design. Inappropriate input, such as SQL expressions, may cause the system to execute undesirable and unauthorized transactions against the database or allow other inappropriate access to the internal network (injection attacks).
The VNF MUST implement the following input validation control on APIs: Validate that any input file has a correct and valid Multipurpose Internet Mail Extensions (MIME) type. Input files should be tested for spoofed MIME types.
4.3.4. VNF Security Analytics Requirements¶
This section covers VNF security analytics requirements that are mostly applicable to security monitoring. The VNF Security Analytics cover the collection and analysis of data following key areas of security monitoring:
- Anti-virus software
- Data capture
- API based monitoring
- Detection and notification
- Resource exhaustion detection
- Proactive and scalable monitoring
- Mobility and guest VNF monitoring
- Closed loop monitoring
- Interfaces to management and orchestration
- Malformed packet detections
- Service chaining
- Dynamic security control
- Dynamic load balancing
- Connection attempts to inactive ports (malicious port scanning)
The following requirements of security monitoring need to be met by the solution in a virtual environment.
Security Analytics Requirements
The VNF MUST support Real-time detection and notification of security events.
The VNF MUST support Integration functionality via API/Syslog/SNMP to other functional modules in the network (e.g., PCRF, PCEF) that enable dynamic security control by blocking the malicious traffic or malicious end users.
The VNF MUST support API-based monitoring to take care of the scenarios where the control interfaces are not exposed, or are optimized and proprietary in nature.
The VNF MUST support detection of malformed packets due to software misconfiguration or software vulnerability, and generate an error to the syslog console facility.
The VNF MUST support proactive monitoring to detect and report the attacks on resources so that the VNFs and associated VMs can be isolated, such as detection techniques for resource exhaustion, namely OS resource attacks, CPU attacks, consumption of kernel memory, local storage attacks.
The VNF SHOULD operate with anti-virus software which produces alarms every time a virus is detected.
The VNF MUST protect all security audit logs (including API, OS and application-generated logs), security audit software, data, and associated documentation from modification, or unauthorized viewing, by standard OS access control mechanisms, by sending to a remote system, or by encryption.
The VNF MUST log successful and unsuccessful authentication attempts, e.g., authentication associated with a transaction, authentication to create a session, authentication to assume elevated privilege.
The VNF MUST log logoffs.
The VNF MUST log starting and stopping of security logging.
The VNF MUST log success and unsuccessful creation, removal, or change to the inherent privilege level of users.
The VNF MUST log connections to the network listeners of the resource.
The VNF MUST log the field “event type” in the security audit logs.
The VNF MUST log the field “date/time” in the security audit logs.
The VNF MUST log the field “protocol” in the security audit logs.
The VNF MUST log the field “service or program used for access” in the security audit logs.
The VNF MUST log the field “success/failure” in the security audit logs.
The VNF MUST log the field “Login ID” in the security audit logs.
The VNF MUST NOT include an authentication credential, e.g., password, in the security audit logs, even if encrypted.
The VNF MUST detect when its security audit log storage medium is approaching capacity (configurable) and issue an alarm.
The VNF MUST support the capability of online storage of security audit logs.
The VNF MUST activate security alarms automatically when a configurable number of consecutive unsuccessful login attempts is reached.
The VNF MUST activate security alarms automatically when it detects the successful modification of a critical system or application file.
The VNF MUST activate security alarms automatically when it detects an unsuccessful attempt to gain permissions or assume the identity of another user.
The VNF MUST include the field “date” in the Security alarms (where applicable and technically feasible).
The VNF MUST include the field “time” in the Security alarms (where applicable and technically feasible).
The VNF MUST include the field “service or program used for access” in the Security alarms (where applicable and technically feasible).
The VNF MUST include the field “success/failure” in the Security alarms (where applicable and technically feasible).
The VNF MUST include the field “Login ID” in the Security alarms (where applicable and technically feasible).
The VNF MUST restrict changing the criticality level of a system security alarm to users with administrative privileges.
The VNF MUST monitor API invocation patterns to detect anomalous access patterns that may represent fraudulent access or other types of attacks, or integrate with tools that implement anomaly and abuse detection.
The VNF MUST generate security audit logs that can be sent to Security Analytics Tools for analysis.
The VNF MUST log successful and unsuccessful access to VNF resources, including data.
The VNF MUST support the storage of security audit logs for a configurable period of time.
The VNF MUST have security logging for VNFs and their OSs be active from initialization. Audit logging includes automatic routines to maintain activity records and cleanup programs to ensure the integrity of the audit/logging systems.
The VNF MUST be implemented so that it is not vulnerable to OWASP Top 10 web application security risks.
The VNF MUST protect against all denial of service attacks, both volumetric and non-volumetric, or integrate with external denial of service protection tools.
The VNF MUST be capable of automatically synchronizing the system clock daily with the Operator’s trusted time source, to assure accurate time reporting in log files. It is recommended that Coordinated Universal Time (UTC) be used where possible, so as to eliminate ambiguity owing to daylight savings time.
The VNF MUST log the Source IP address in the security audit logs.
The VNF MUST have the capability to securely transmit the security logs and security events to a remote system before they are purged from the system.
The VNF SHOULD provide the capability of maintaining the integrity of its static files using a cryptographic method.
The VNF MUST log automated remote activities performed with elevated privileges.
4.3.5. VNF Data Protection Requirements¶
This section covers VNF data protection requirements that are mostly applicable to security monitoring.
Data Protection Requirements
The VNF MUST provide the capability to restrict read and write access to data handled by the VNF.
The VNF MUST Provide the capability to encrypt data in transit on a physical or virtual network.
The VNF MUST provide the capability to encrypt data on non-volatile memory.Non-volative memory is storage that is capable of retaining data without electrical power, e.g. Complementary metal-oxide-semiconductor (CMOS) or hard drives.
The VNF SHOULD disable the paging of the data requiring encryption, if possible, where the encryption of non-transient data is required on a device for which the operating system performs paging to virtual memory. If not possible to disable the paging of the data requiring encryption, the virtual memory should be encrypted.
The VNF MUST use NIST and industry standard cryptographic algorithms and standard modes of operations when implementing cryptography.
The VNF MUST NOT use compromised encryption algorithms. For example, SHA, DSS, MD5, SHA-1 and Skipjack algorithms. Acceptable algorithms can be found in the NIST FIPS publications (https://csrc.nist.gov/publications/fips) and in the NIST Special Publications (https://csrc.nist.gov/publications/sp).
The VNF MUST use, whenever possible, standard implementations of security applications, protocols, and formats, e.g., S/MIME, TLS, SSH, IPSec, X.509 digital certificates for cryptographic implementations. These implementations must be purchased from reputable vendors or obtained from reputable open source communities and must not be developed in-house.
The VNF MUST provide the ability to migrate to newer versions of cryptographic algorithms and protocols with minimal impact.
The VNF MUST support digital certificates that comply with X.509 standards.
The VNF MUST NOT use keys generated or derived from predictable functions or values, e.g., values considered predictable include user identity information, time of day, stored/transmitted data.
The VNF MUST provide the capability of using X.509 certificates issued by an external Certificate Authority.
The VNF MUST be capable of protecting the confidentiality and integrity of data at rest and in transit from unauthorized access and modification.
4.3.6. VNF Cryptography Requirements¶
This section covers VNF cryptography requirements that are mostly applicable to encryption or protocol meethods.
The VNF SHOULD support an automated certificate management protocol such as CMPv2, Simple Certificate Enrollment Protocol (SCEP) or Automated Certificate Management Environment (ACME).
The VNF SHOULD provide the capability to integrate with an external encryption service.
The VNF MUST use symmetric keys of at least 112 bits in length.
The VNF MUST use asymmetric keys of at least 2048 bits in length.
The VNF MUST provide the capability to configure encryption algorithms or devices so that they comply with the laws of the jurisdiction in which there are plans to use data encryption.
The VNF MUST provide the capability of allowing certificate renewal and revocation.
The VNF MUST provide the capability of testing the validity of a digital certificate by validating the CA signature on the certificate.
The VNF MUST provide the capability of testing the validity of a digital certificate by validating the date the certificate is being used is within the validity period for the certificate.
The VNF MUST provide the capability of testing the validity of a digital certificate by checking the Certificate Revocation List (CRL) for the certificates of that type to ensure that the certificate has not been revoked.
The VNF MUST provide the capability of testing the validity of a digital certificate by recognizing the identity represented by the certificate - the “distinguished name”.
The VNF MUST support HTTP/S using TLS v1.2 or higher with strong cryptographic ciphers.
The VNF MUST support the use of X.509 certificates issued from any Certificate Authority (CA) that is compliant with RFC5280, e.g., a public CA such as DigiCert or Let’s Encrypt, or an RFC5280 compliant Operator CA.
Note: The VNF provider cannot require the use of self-signed certificates in an Operator’s run time environment.