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The Top 10 Serverless Security Best Practices

For the past few years, serverless computing has highly revolutionized the way we develop and deploy applications, offering scalability, cost-effectiveness, and reduced operational overhead. But with great power comes great responsibility, and in this case, it’s the responsibility of ensuring serverless security. 

That being said, in this blog, we will explore various aspects of serverless security and explore serverless security best practices to safeguard your serverless infrastructure effectively.

Let’s dive right in!

What Is Serverless Security?

As businesses make the transition to serverless computing, the significance of serverless security has been on the rise. However, what precisely does serverless security entail, and what sets it apart in the domain of cloud computing?

Serverless security encompasses the array of methods, tools, and tactics deployed for securing serverless applications and the foundational infrastructure against potential risks and vulnerabilities. 

Contrasting with traditional server-centric architectures, serverless computing abstracts away the management of servers, making it more challenging to apply conventional security approaches.

In fact, within a serverless environment, security is a shared responsibility between the cloud provider and the application owner, making it crucial to understand and implement best practices on both fronts.

The Mechanics of Serverless Security

Comprehending the inner workings of serverless security plays a vital role in successfully establishing and upholding a secure serverless ecosystem.

In this segment, we’ll discuss the fundamental components and procedures that underpin the functionality of serverless security.

Authentication and Authorization

Authentication serves as the process that verifies the legitimacy of users or systems seeking access to serverless resources. Its primary role is to ensure that solely authorized individuals or processes have the privilege to interact with your serverless functions and data. 

On the other hand, authorization establishes the scope of actions authenticated users or systems can undertake within your serverless environment. It stipulates permissions and access controls, guaranteeing that even authenticated entities can solely execute sanctioned operations.

Function Isolation

Serverless platforms inherently segregate functions from one another. This ensures each function operates within its own encapsulated environment to provide essential isolation and security.

However, configuring this isolation with precision is crucial to prevent unintended interactions or data breaches between functions.

Data Encryption

Data encryption constitutes a fundamental cornerstone of serverless security. It mandates the encryption of both data in transit (e.g., during API interactions) and data at rest (e.g., data stored in databases or object storage). The objective is to shield the data from unauthorized access and tampering.

Security Policies and IAM

IAM policies define the entities that are authorized to access your serverless resources and specify the actions they can execute. IAM policies form the bedrock of serverless security, and precision in control is indispensable for mitigating potential security vulnerabilities.

Monitoring and Logging

Robust monitoring and comprehensive logging are indispensable for the identification and response to security incidents within a serverless environment.

Real-time monitoring, alerting mechanisms, and comprehensive logs yield insights into unforeseen or potentially malicious activities.

Security Tools Tailored for Serverless Environments

Given the distinct requirements of serverless security, specialized tools, and services have emerged to cater to these specific needs. These serverless security tools aid in examining code for vulnerabilities, enforcing security policies, and detecting anomalies within your serverless applications.

Security Evaluation and Auditing

Regularly assessing your serverless applications for security susceptibilities constitutes an integral facet of serverless security. Automated testing, meticulous code reviews, and security audits serve as methodologies for identifying and rectifying potential weaknesses.

Benefits of Serverless Security

Benefits of Serverless Security

Serverless security isn’t just about mitigating risks and preventing security breaches; it also offers a range of benefits that can significantly enhance your organization’s security posture.

In this section, we’ll explore the advantages of investing in serverless security measures: 

Reduced Attack Surface

Architectures that are serverless obscure the underlying server infrastructure, diminishing the available attack surface for potential intruders. Fewer entry points into your system translate into fewer opportunities for malicious activities.

Automatic Scalability

Serverless platforms autonomously adjust the scale of your functions in response to demand. This ensures that your application can handle surges in traffic without manual intervention, thereby reducing the risk of overloading resources and introducing serverless vulnerabilities.

Managed Security

Cloud providers offering serverless platforms often furnish managed security services such as DDoS protection, firewalls, and automated security patching. These services secure your applications against common security threats.

Built-In Authentication

Platforms that are serverless frequently incorporate built-in authentication and authorization features, streamlining the process of securing your applications without the necessity for extensive custom code.

Streamlined Infrastructure Management

Serverless architecture eliminates the requirement to oversee server infrastructure, alleviating the burden of maintaining, updating, and patching operating systems—a common source of security vulnerabilities.

Challenges of Serverless Security

Challenges of Serverless Security

While serverless security offers numerous benefits, it also presents unique challenges that organizations must address to ensure the protection of their applications and data. Here are some of the serverless security challenges that should be considered: 

Dependency Complexity: Serverless applications often rely on various third-party services, libraries, and APIs. These dependencies can introduce security risks, especially if not properly vetted and monitored.

Cold Start Vulnerabilities: The “cold start” problem, where serverless functions experience a delay when first invoked, can lead to security challenges. Attackers can exploit this delay to launch timing-based attacks.

Secure Configuration: Misconfigurations on serverless platforms, such as overly permissive permissions or improper authentication settings, can create vulnerabilities that attackers can exploit.

Security Testing Tools: Traditional security testing tools may not be well-suited for serverless applications, requiring organizations to invest in serverless-specific security testing solutions.

Identity and Access Management (IAM): Effectively configuring IAM policies is complex and critical to serverless security. Misconfigured IAM policies can lead to data breaches and unauthorized access.

Cross-Function Security: Ensuring that one function within a serverless application cannot compromise the security of another function is a critical concern in serverless security.

Top 10 Serverless Security Best Practices

1. Least Privilege Access

This practice involves granting serverless functions only the permissions they absolutely need to function correctly. By adhering to the principle of least privilege, you reduce the attack surface and minimize the risk of unauthorized access. It means ensuring that your functions can perform their intended tasks without unnecessary, potentially risky, permissions. 

Effective access control, implemented through Identity and Access Management (IAM) policies, plays a vital role here. By restricting permissions to the minimum necessary for each function, you prevent malicious actors or vulnerabilities from exploiting overly broad privileges.

To put it more clearly, the following JSON snippet illustrates an IAM policy for an AWS Lambda function.

  "Version": "2012-10-17",
  "Statement": [
      "Effect": "Allow",
      "Action": [
      "Resource": "arn:aws:s3:::your-bucket/*"

Let’s break down the components of this IAM policy:

  • Effect“: “Allow“: This specifies that the permissions described in the statement are allowed.
  • “Action”: [“s3:GetObject”]: This is the action that is allowed. In this case, it allows the Lambda function to perform the GetObject action on the S3 bucket.
  • “Resource”: “arn:aws:s3:::your-bucket/*”: This specifies the resource on which the action is allowed. It restricts the permission to a specific S3 bucket (your-bucket), allowing the Lambda function to perform GetObject only on objects within that bucket (/*).

2. Secure Configuration

Securing your serverless functions begins with robust configuration. Misconfigured functions can lead to vulnerabilities, making it crucial to double-check and secure your settings. Start by scrutinizing environment variables, memory allocations, and timeout settings. 

Always ensure that external integrations, like database connections or API endpoints, are properly configured with secure authentication and access control. Always favor secure defaults when configuring your serverless services, as they are often designed with security in mind. Regularly review and update your configurations to adapt to changing security requirements and best practices.

3. Data Encryption

Encrypting sensitive data is a fundamental safeguard against unauthorized access and data breaches. In a serverless environment, you must address encryption in transit and at rest. For data in transit, use secure communication protocols such as HTTPS to encrypt data transmitted between your functions and external services. 

When it comes to data at rest, leverage encryption mechanisms provided by your cloud provider for databases, storage, and other persistent data stores. Encryption keys should be securely managed and rotated regularly. By implementing these encryption practices, you ensure that even if an attacker gains access to your data, it remains indecipherable and secure.

4. API Authentication

Robust authentication mechanisms are essential for securing the APIs that connect your serverless functions. APIs often serve as the entry point for data exchange between functions and external systems. To prevent unauthorized access, implement authentication and authorization solutions. This can include API keys, OAuth, or token-based authentication, depending on your specific use case. 

Authenticate and verify the identity of users or systems making requests to your functions, ensuring that only authorized entities can access your services. Additionally, employ rate limiting and consider implementing Web Application Firewall (WAF) services to further protect your APIs from common attacks like DDoS and injection attempts.

Let’s consider a simple example using token-based authentication:

def authenticate_request(request):
    # Check if the request contains a valid token
    token = request.headers.get('Authorization')

    if not token or not validate_token(token):
        # Unauthorized access, handle accordingly
        return False
        # Authorized access
        return True

# Example usage in a serverless function
def my_serverless_function(request):
    if authenticate_request(request):
        # Process the request because it's authorized
        return "Request processed successfully."
        # Unauthorized request, return an error
        return "Unauthorized access. Please provide a valid token."

Here, the authenticate_request function examines the incoming request to ensure it includes a valid token in the headers. If a valid token is not present or fails validation, the function returns “False”, indicating unauthorized access. Otherwise, it returns “True”, signaling that the request is authorized, allowing the serverless function to proceed with processing the request.

5. Regular Security Testing

Continuous security testing is a cornerstone of serverless security. Automated serverless security scanning tools, code reviews, and security audits should be integrated into your deployment pipeline to identify and remediate vulnerabilities. Regular testing helps you stay on top of potential security issues and reduce the risk of deploying flawed code. 

This practice includes static analysis to catch vulnerabilities early in the development process, dynamic analysis for runtime testing, and interactive analysis to provide feedback directly to developers as they write code. By routinely assessing your serverless applications for weaknesses, you can take proactive steps to address and mitigate security concerns before they become critical threats.

6. Secure Dependencies

Serverless applications often rely on various third-party libraries, modules, and services. It’s vital to be cautious about the security of these dependencies since any vulnerabilities in them could be exploited by attackers.

Keep an inventory of your dependencies, and actively monitor their security status. Subscribe to security notifications for the libraries you use and apply updates or patches promptly. 

Also, consider using tools that automatically scan your application’s dependencies for known vulnerabilities.

Secure coding practices and careful dependency management are key to reducing the risk associated with third-party components, ensuring that your serverless functions remain resilient against security threats.

7. Function Isolation

Function isolation is a key aspect of serverless security. Serverless platforms inherently run each function in its isolated execution environment. Properly configuring this isolation is crucial to prevent one function from compromising the security of others. For instance, make sure functions don’t accidentally share resources or data.

By keeping a clear separation between functions, you lower the chances of data leakage and unauthorized access. You can also add an extra layer of protection by using custom runtime settings and environment variables to fine-tune how isolated your functions are. 

Here’s a simple example:

// Function 1
exports.handler1 = async (event) => {
    // Code for function 1
    const data = event.body;
    // Process data for function 1
    return {
        statusCode: 200,
        body: JSON.stringify({ message: 'Function 1 executed successfully' }),

// Function 2
exports.handler2 = async (event) => {
    // Code for function 2
    const secretInfo = event.headers.Authorization;
    // Process data for function 2
    return {
        statusCode: 200,
        body: JSON.stringify({ message: 'Function 2 executed successfully' }),

In this example, handler1 and handler2 are separate serverless functions. Function 1 processes data from the request body, while Function 2 retrieves a secret from the request headers. 

On maintaining proper isolation, we ensure that the data processed in Function 1 doesn’t unintentionally impact the execution of Function 2, and vice versa.

This separation helps prevent unintended access to sensitive information and enhances the security of the serverless application.

8. Monitoring and Logging

Effective monitoring and logging are essential for identifying and responding to security incidents in real-time. Set up comprehensive monitoring systems to track the behavior of your serverless functions, including performance metrics, execution logs, and error reports. Configure alerts that notify you when anomalies or suspicious activities are detected. 

Ensure that logs capture relevant security events, such as failed login attempts or unauthorized access, and store them securely. By continuously monitoring and analyzing your application’s activity, you can quickly detect and respond to security incidents, minimizing their impact.

9. Security Awareness

Security awareness and education are crucial for maintaining a strong security culture within your development and operations teams. Ensure that your teams are well-versed in serverless security best practices.

Provide serverless security workshops, training, and resources to help them understand the unique challenges and strategies for securing serverless applications.

Encourage the adoption of security by design principles, where security is integrated into the development lifecycle from the beginning.

By following a security-conscious culture, you empower your teams to proactively address security concerns and make informed decisions that enhance the overall security of your serverless applications.

10. Incident Response Plan

Having a well-defined incident response plan is essential for efficiently addressing security breaches. Outline a clear process for identifying, containing, and mitigating security incidents.

Define roles and responsibilities for incident response team members and establish communication protocols to ensure everyone knows how to respond when a breach occurs. 

Plus, test your incident response plan through simulated exercises to evaluate its effectiveness and make necessary adjustments. A well-prepared incident response plan can mean the difference between containing a security incident promptly and enduring prolonged downtime and data breaches.


Is serverless faster than server?

Serverless technology may yield faster response times for specific tasks by dynamically adjusting resources to meet incoming demands. Nevertheless, the speed differential varies according to the specific usage and the efficiency of the serverless application’s design.

How can serverless improve security?

Serverless can enhance security through its automatic resource scaling, managed infrastructure, and the inclusion of inherent security features provided by cloud service providers. It reduces potential points of attack, facilitates secure setups, and simplifies security administration, thus streamlining the implementation of security best practices.

Is serverless inherently less secure? 

Serverless technology isn’t inherently less secure, but it does introduce unique security complexities. Issues like misconfigurations, dependencies, and insufficient access control can introduce vulnerabilities. Tackling these concerns with best practices remains crucial in maintaining a secure serverless environment.


In this blog, we’ve explored the top 10 serverless security best practices, each designed to safeguard your applications and data. By carefully implementing these practices, you can build a resilient and secure serverless environment that protects against evolving threats. In fact, it’s crucial to remember that security is an ongoing journey, not a one-time destination. 

For additional support in boosting your security infrastructure, consider CloudDefense.AI. Trusted by some of the world’s largest companies, CloudDefense.AI offers state-of-the-art security solutions. Strengthen your security today – book your free demo with CloudDefense.AI and take your security to the next level.

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Anshu Bansal
Anshu Bansal
Anshu Bansal, a Silicon Valley entrepreneur and venture capitalist, currently co-founds CloudDefense.AI, a cybersecurity solution with a mission to secure your business by rapidly identifying and removing critical risks in Applications and Infrastructure as Code. With a background in Amazon, Microsoft, and VMWare, they contributed to various software and security roles.
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