1. ETSI EN 303 645
The European Telecommunications Standards Institute (ETSI) specifies 65 security provisions for consumer IoT devices that are connected to a network. The standard is meant for organisations involved in the development and manufacturing of consumer IoT devices, i.e. vendors. As such, it aims to provide a relatively complete set of requirements. The requirements are less useful for testing a finished product; in a black box test it is difficult to observe whether some provisions have been implemented or not. Even so, it is a complete and usable set of provisions, and it supports most provisions, with examples and rationales provided.
The wording of the provisions is such that it makes it clear that ETSI wants to avoid restricting devices to a specific technology or protocol. For example, a requirement on passwords may prevent devices from using an authentication mechanism that does not rely on passwords. Therefore, EN 303 645 uses the term “authentication value” instead of “password”. Unfortunately, in certain cases this makes the provisions insufficiently specific. For example, in the following provision there is a lot of room for interpretation as to what cryptographic algorithm should be used: Provision 5.1-3 Authentication mechanisms used to authenticate users against a device shall use best practice cryptography, appropriate to the properties of the technology, risk and usage.
Overall, ETSI 303 645 is a practical, usable guide that provides vendors with measures to secure IoT devices.
IoT Security Compliance Framework
The IoT Security Foundation released the IoT Security Compliance Framework, which comprises a set of 233 requirements.
Requirements are either mandatory or advisory, and are applicable to certain device classes, which depend on the impact of a compromised device. Devices where a hack would cause minor inconvenience is denoted Class 0 and less security measures apply to such devices. Devices that handle sensitive data are denoted Class 3, and for these most security measures apply. As many devices handle sensitive data in some form, the security requirements this framework imposes are pretty strict.
The division into classes largely ignores the indirect, societal impact of attacks. Even if the device does not have strict security requirements, it can still be used in a DDoS attack on a unrelated website.
The framework contains many requirements that enforce a secure business process, or require a secure design. This helps vendors to consider security during the design process.
Even though these are good recommendations to help vendors secure products, these requirements are less useful for black-box testing to determine whether a device conforms to these requirements. For example,
126.96.36.199, “maintenance changes should trigger full security regression testing”,
applies more to the business process than to the functionality of the device.
Even so, there are also many requirements that are sufficiently specific and measurable. For example, one of the simplest and most important requirements is
188.8.131.52: the product does not accept the use of null or blank passwords.
The framework has a wide scope, and includes security requirements for mobile applications, cloud services, the supply chain and the production process. This causes several very similar requirements; passwords should be secure for the IoT device, for the mobile application, for the web interface, etc.
The OWASP Internet of Things Security Verification Standard (ISVS) provides security requirements for Internet of Things (IoT) applications. It is modelled after the Application Security Verification Standard (ASVS), a standard that is growing in popularity for the verification of security controls for web-applications and web services.
The ISVS is currently in the very early stages of development where the latest public version is released as an appendix to the ASVS standard. It consists of a list of 34 verification requirements that are predominantly targeted at the technical security aspects of an IoT application.
In its current form, as part of the ASVS, the ISVS defines three assurance levels with increasing depth. This essentially means that an IoT application is verified against more requirements when a higher security level is selected. Level 1 requirements can be considered as the bare minimum. The requirements at this level are typically easy to verify. Level 2 introduces requirements that defend against the majority of today’s security risks. Level 3 is reserved for applications that need a high level of assurance and require significant security verification. Examples of such applications are in the area of military, health, financial or critical infrastructures.
ENISA Baseline Security Recommendations for IoT
The ENISA (European Union Agency for Cybersecurity) Baseline Security Recommendations for IoT provides measures on three main categories: - Policies - Organisational, People and Process measures - Technical measures
The measures regarding policies target the development process at the vendor. Virtually all of these are insufficiently SMART when applied to the end product of the process, the IoT device. The Organisational, People and Process measures target the interaction between the vendor and the consumer, and cover vulnerability disclosure, for example. Finally, the technical measures provide the most concrete measures of how the IoT device should behave.
Several of the measures that are included as a single point in the ENISA document actually consist of several requirements. For example:
GP-TM-18: Ensure that the device software/firmware, its configuration and its applications have the ability to update Over-The-Air (OTA), that the update server is secure, that the update file is transmitted via a secure connection, that it does not contain sensitive data (e.g. hardcoded credentials), that it is signed by an authorised trust entity and encrypted using accepted encryption methods, and that the update package has its digital signature, signing certificate and signing certificate chain, verified by the device before the update process begins.
This one measure consists of at least eight requirements. This makes it difficult to categorize and evaluate.
The ENISA measures are meant to provide information on how to secure devices. Several measures dictate that a specific part of the device should be secure. For example:
GP-TM-35: Cryptographic keys must be securely managed.
It is self-evident that for a device to be secure, all its subcomponents need to be secure. However, for vendors that are unaware of how to develop secure components, indicating that something must be secure may be insufficient. For testers, it may even be unclear what level of security is demanded, or against what kind of attack the system should be secure. Most of these measures have been discarded as insufficiently specific.
Using any one of these frameworks can help to secure IoT devices. When to use which framework? For vendors, we recommend the following:
- Implement ETSI 303 645 for mature, well explained and specific instructions on how to achieve basic security in IoT devices.
- If you want additional security, not only in the device but in the business process and the surrounding systems, use the IoT Security Compliance Framework.
- If you want a checklist, or verify after development whether a product is secure, use the OWASP IoT Security Verification Standard.
- If you want a less formal process, but are in need of good recommendations on how to secure your devices, consult the ENISA guidelines.
For hackers and testers, the OWASP ISVS has potential to be the best match. It is specifically meant to provide a checklist of things to verify when testing. However, it is also a immature project. As alternative, ETSI 303 645 is sufficiently specific to be usable for testers.