8 Serverless Security Best Practices for Any Cloud

Time, cost, and quality – hitting this trifecta is the ultimate goal of any software organization. Its pursuit over decades has resulted in multiple application development methodologies like serverless computing, an emerging and popular cloud computing model touted as the future. 

Nearly 70% of organizations will increase their usage of serverless computing by 2025. While serverless architecture offers several benefits, like reduced operational costs and agility, it is also prone to frequent cyberattacks. As with any new application development innovation, more contemporary security challenges arise, and attack vectors constantly evolve with development practices. 

This blog post focuses on serverless security, its challenges and benefits, and some best practices to harden your serverless application. Let’s dive in.

What is serverless security?

Serverless security is a layer of protection aimed at code functions. It is applied directly to the applications, enabling developers to enforce compliance for enhanced security posture. But to understand its significance, let’s take a step back to learn about serverless architecture.

Serverless architecture

Serverless architecture is a software development approach where you design and run your application without worrying about the underlying infrastructure. Your team will only handle writing and executing the code, while your cloud provider will facilitate the application’s servers.

In the early days of software development, you had bare metal servers managed by system admins to deploy applications. It was not resourced extensively but was costly. However, innovations in cloud computing, virtual machines, and containerized applications made building applications flexible, easy, and fast. Serverless computing is like the next movie in the franchise.

The purpose of servers is to facilitate interaction between users and applications. Although essential, servers add quite a bit of complexity, IT operations overhead, and cost. On the other hand, the serverless architecture enables developers to focus on writing quality code instead of maintaining servers, creating backups, and ensuring security. It’s more economical since you only pay for the services you use and use them only when running the application. 

With a serverless architecture like Function as a Service (FaaS), you can write your code as small bits of functions that run when triggered by an event. But the deal is that you also hand over the security to the cloud service provider, which is helpful. With serverless architecture providing automated workflow, you get scalability, faster application delivery, and reduced development costs.

What are the benefits of serverless architecture?

Serverless architecture is an event-based methodology against stream-based, making it more resilient to failures. So when the application experiences a failure, it impacts the specific event and not the entire log. Here are five other benefits of using serverless architecture.

• By outsourcing server and database management, you significantly reduce the operational cost of human resources to manage the infrastructure and the computing space.
• When you hand over the security control of your infrastructure to the cloud provider, you enforce runtime security, key and secrets management, and other best practices like patching automatically. With providers like Azure, AWS, and Google Cloud implementing their security measures, your application code is covered with basic policies.
• Application containers become tough targets for attacks because they are terminated when they’re not actively running. The stateless characteristic becomes a security posture in itself.
• Through serverless architecture, you break down your application into small packages, which makes it easy for you to track and monitor your serverless applications.
• You get the ability to implement IAM for every small function, which strengthens your security.

What are the challenges of serverless architecture?

It’s not all rosy with serverless computing and it has some challenges too.

Security misconfigurations

While cloud service providers offer a range of security features and settings, you must configure them properly. Leaving anything out or misconfiguration in any setting can turn into a risk.

Improper permission privileges

The downside of setting individual access to multiple functions is that you could give a user more privileges than necessary. You must always implement least or zero privilege permissions to reduce attack possibilities.

Event-data injections

When an event is triggered, it could inject untrusted inputs into the functions. Therefore, you need to carefully assess every event source for illegal data injections.  

Verbose error messages

Neglecting verbose error messages like out of memory, null pointer, multiple other errors, and improper exception handling can give hackers a vulnerability to exploit and launch an attack.

Third-party vulnerabilities

Developers will have to share the responsibility of securing the application along with the cloud providers to tackle vulnerabilities that come with database services, backend cloud services, application-associated configurations, etc.

8 Serverless Best Practices for any Cloud

The features that make a serverless architecture so appealing are also the ones that weaken its security. For example, while the multiple functions of applications enable fine-grained security policy enforcement, they also increase the number of entry points that attackers can target. Protecting your application from attacks means implementing best practices for serverless security.

1. Protect against insecure application access using layered access control and authentication. Your cloud provider will offer multiple solutions to avoid the risk of broken authentication. Some of the tools include OAuth, SAML, and OpenID Contact. Along with a multi-factor authentication system, you can design and implement password complexity that suits your development culture.
   
2. Efficient monitoring and logging of your function runtime and user access is critical in reducing exposure to security attacks. Although your cloud provider offers observability and monitoring capabilities, it is smart to invest in a third-party tool that gives you monitoring-specific features making an intuitive experience.
   
3. Implement the least privileged access through a firm permission policy by assigning unique roles for each function. Due to the daunting task of giving permission access to every function, developers tend to over-privilege, leading to a security lapse that attackers love to leverage. The ideal practice is for your security and development teams to sit and discuss the purpose of each function and the necessary security measures it will require.
   
4. Keep control of your functions by implementing proper code analysis policies to ensure you don’t push tainted code for deployment. With malicious actors targeting employees instead of the application code, it is essential to implement security policies to check that every function pushed through to the CI/CD pipeline is clean without any rogue elements. 
   
5. Enforce substantial runtime for your functions by setting a ticking clock for every function so it is terminated when the task is done. Through serverless function timeouts, you can take away any opportunity for hackers to inject illegal code into your application. You should also pay attention to the runtime you assign – developers tend to go with the maximum time allowed, which means attackers get more time to do something bad.
   
6. Steer clear of third-party dependencies by adopting a stringent process to verify the authenticity and reliability of sources. Also, ensuring that you use the latest version of components from an open-source code will give you the most sound code at that moment. Another key best practice when using open-source components is to always keep them up to date. 
   
7. Pay close attention to sensitive credentials like API keys for efficient secrets management. It’s good practice to add period evaluation in configuration files or utilize a secrets scanning tool like Spectral to automate this process for you. 
   
8. Implement security across the SDLC, not just during the testing phase. Integrating security in every stage of development will help you reduce operational costs and avoid delays. Also, the continuous review will highlight security gaps and places where strong protection policies are needed.

Serverless Security isn’t Just the Cloud Provider’s Responsibility

Serverless computing is a unique and powerful software development practice that eases infrastructure management, facilitates scalable applications, and produces quality code. Building a serverless application requires a robust security strategy, including performance tracking and code analysis procedures. In serverless applications, cloud providers protect infrastructure while developers focus on writing and deploying code. 

Although cloud service providers offer and implement their cloud security tools and practices, it’s not the end of the road. Developers must claim equal responsibility in hardening serverless security. And for this, you will need third-party tools like SpectralOps, a comprehensive security tool that facilitates code safety and trust through automated processes like infrastructure-as-code scanning, hardcoded secrets detection, and source code leakage detection. It accelerates the implementation of security best policies in seconds by shift-left philosophy. 

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