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What You Need to know about API security

API Security

When people talk about complex, interconnected ecosystems, they’re really talking about how applications share data and communicate with each other. Like the air-lock on a spaceship lets people pass between physical environments, Application Programming Interfaces (APIs) enable data to pass between digital environments. However, since APIs act as access points between applications, they create potential security risks.


By understanding API security, you can implement protections that mitigate data breach risks.


What is API security?

API security is the set of controls and processes that protect organization-owned and external APIs that an organization uses to ensure sensitive data travels safely between applications. Since APIs are the point of communication between different pieces of software, threat actors seek to exploit vulnerabilities so that they can steal the data.


An API gateway sits between the client and the services, creating a centralized location for implementing security policies that enforce basic controls like:

  • Authentication
  • Authorization
  • Access
  • Encryption


What are API vulnerabilities?

API vulnerabilities are the security weaknesses that malicious actors can exploit during an attack to gain unauthorized access to data, manipulate it, or disrupt how a system functions. Some API vulnerabilities include:

  • Exposing endpoints that handle object identifiers
  • Misconfiguring authentication mechanisms
  • Making too many resources available via API
  • Authorization flaws across complex access control policies
  • Exposing business data flows
  • Allowing remote resource access without validating the requesting party


Attackers exploit these vulnerabilities as part of:

  • Injection attacks: inserting malicious code or commands into API requests
  • Denial of Service (DoS) attacks: overloading the APIs with so many requests that it becomes unresponsive
  • Privilege escalation: using weak or ineffective authentication methods to gain establish initial access


Why is API security important?

As more companies rely on web-based applications to achieve business objectives, API security becomes more important. Sensitive data transfers via API create risks when threat actors can gain unauthorized access to the data. Since APIs act as the digital entrance to an application, mitigating risks arising from API vulnerabilities and misconfigurations is critical to:

  • Application security: protecting against unauthorized access to applications and their data
  • Network security: preventing attackers from leveraging APIs as an entry point for unauthorized access to networks
  • Information security: mitigating risks that attackers will gain unauthorized access to data that allows them to view, steal, change, or delete sensitive data


What is the difference between API security and application security?

While API security focuses on the interface between applications, application security considers the layers and components within the application.


API security handles data transmission between systems, enforcing access controls and authentication mechanisms.


Application security aims to protect the data within the application and its infrastructure by addressing vulnerabilities and risks, like:

  • Input validation
  • Authentication and authorization
  • Secure coding practices
  • Protection against common attacks


Attack vector

API security takes a technology-centric approach by securing the communication point between software systems. To protect the resources and data exchanged between applications, it ensures that only authorized and authenticated systems can access and interact with the API.


Application security takes a user-centric approach, focusing on end-users who interact directly with the technology by:

  • Securing user credentials
  • Protecting sensitive user information
  • Ensuring secure use authentication and authorization processes



The difference in scope and attack vector lead to a different set of tools for each initiative.


The tools that enable API security include:

  • API management systems
  • API gateways
  • Web Application Firewalls (WAFs)


The tools that enable application security include:

  • Application security testing tools, like dynamic testing, static testing, and interactive testing
  • Vulnerability management
  • Identity and access management (IAM)


9 API security best practices


While API security is challenging, you can take some steps to secure your APIs and application ecosystem.


1.   Identify and inventory APIs

As with other digital assets, you need to know the APIs that connect to your systems. When identifying and inventorying APIs, you should collect API:

  • Names
  • Versions
  • Endpoints
  • Purpose
  • Connections, including systems and applications


2.   Engage in a risk assessment

To proactively secure your APIs, you need to understand your risk profile. As part of this process, you should consider:

  • Identifying all API endpoints an application exposes
  • Evaluating API configuration settings to mitigate the risk that they expose sensitive information or grant unauthorized access to the API
  • Threat modeling to identify risk factors like ata transmitted, breach impact, likelihood of attack types
  • Penetration testing to identify and remediation vulnerabilities


3.   Validate data

Data validation is critical to mitigating injection attack risks. You should verify that the data users input is the expected:

  • Type
  • Format
  • Length

Additionally, you should ensure that any data users submit satisfies the API’s requirements or conditions.


4.   Implement Strong Authentication and Authorization


Authentication and authorization for APIs is different from your user IAM processes. Since APIs include digital and human access, validation and authentication becomes more challenging. Client-side applications typically include a token in the API call that validates the client. Some standards that enable you to authenticate API traffic and define access control include:

  • OAuth 2.0
  • OpenID Connect
  • JSON


5.   Encrypt data-in-transit


When securing API communication channels, data encryption prevents attackers from reading or using any data. To protect data-in-transit as it moves between applications, you should use Transport Layer Security (TLS) or Secure Sockets Layer (SSL) protocols.


6.   Limit access appropriately

To prevent unauthorized access or misuse of API endpoints, you should implement the principle of least privilege granting only the access people need to carry out their job functions. Some best practices for APIs include:

  • Role-based access controls (RBAC)
  • Token-based authentication
  • IP filtering
  • Validation using secure tokens


7.   Implement quotas and throttling


Throttling and quotas help prevent malicious actors from abusing APIs or gaining unauthorized access.  With throttling, you regulate the incoming request flow to mitigate risks arising from excessive usage. By setting a maximum request rate, you prevent high incoming traffic volumes from overwhelming APIs. These activities protect against brute force and DoS attacks.


By implementing quotas, you manage resources and prevent abuse by limiting:

  • Total number of requests
  • Amount of data transferred


With quotas, you gain visibility into how users and applications interact with resources. Once you set baselines, you can identify anomalous use that may indicate an attack.


8.   Secure API keys

The keys authenticate and authorize access to APIs, so protecting them is critical. Some ways to secure your APIs keys include:

  • Using a secure storage mechanism rather than hardcoding them into codebase or configuration files
  • Encrypting them and keeping encryption keys separate from API keys
  • Granting limited access to API keys
  • Rotating API keys regularly
  • Monitoring API keys for unusual or excessive access indicating a potential security incident


9.   Continuously monitor API activity


With API logging and monitoring, you gain visibility into the behavior and usage. After identifying baseline norms, you can monitor API traffic and behaviors to detect anomalies and suspicious activities indicating potential security issues.


Some best practices for API logging and monitoring include:

  • Configure APIs to generate logs with timestamps, request and response headers, API endpoints accesses, user identifiers, and error or exception messages
  • Centralized logs in a secure, scalable location so you can easily search, analyze, and correlate data across multiple sources
  • Create high-fidelity real-time alerts for risky behavior like increase in failed login attempt or access to sensitive APIs outside of authorized hours
  • Detect anomalies with machine learning (ML) to identify potential security threats that may evade traditional rule-based monitoring


Graylog Security: Centralized API logging and monitoring


Built on the Graylog platform, Graylog Security provides the functionality of a security incident and event management (SIEM) without the complexity and cost. With our Security Analytics, Incident Investigation, and Anomaly Detection capabilities, you can implement the API monitoring that protects your organization’s complex application environment. With our out-of-the-box cybersecurity focused content, you can get the actionable API insights you need faster while reducing your alert fatigue with our high-fidelity alerts.


To see how Graylog Security can help you uplevel your security, contact us today.


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