API Security Guide
Application Programming Interface, also known as API, is currently dominating the development market. Many modern enterprises, banks, autonomous vehicles, and IoT, have APIs tightly integrated into their infrastructure.
An Essential Guide for API Security in your SaaS Products
Introduction
Application Programming Interface, also known as API, is currently dominating the development market. Many modern enterprises, banks, autonomous vehicles, and IoT, have APIs tightly integrated into their infrastructure. This is because APIs allow developers to integrate external services without having to develop them from scratch.
Despite a number of obvious advantages, APIs also pose security threats like exposing application logic and other sensitive information like Personally Identifiable Information. APIs simply cannot be eliminated from development environments, so the only way forward is to secure APIs.
API Security
The API security framework consists of guidelines and solutions aimed at addressing the unique challenges of API security. The wide adoption of APIs in the development environment also provides a large attack surface for cybercriminals. APIs have been around for years, but the approaches to adopting them have changed as a result of technologies such as mobile applications, cloud, and containers. Such large-scale adoption also requires a modern security approach to counter ever-growing cyber-attacks.
Security Challenges for APIs
There are several security challenges that developers face during the development of a robust and modular application. Due to a spike in API-based cyberattacks, a software security organization named “The Open Web Application Security Project (OWASP)” has developed a top-10 list of the most critical API security risks entitled “The OWASP API Security Top 10”. The list below follows its 2019 edition; OWASP published an updated edition in 2023. Enterprises can plan their security framework based on these threats.
APIs by nature can expose endpoints while handling object identifiers. Any function that accepts user input to access a data source can result in broken object level authorization. These functions must be verified with object-level authorization checks.
Another issue that can lead to unauthorized access is incorrect authentication implementation. An attacker can exploit the authentication tokens or pretend to be a legitimate user to gain access to the system.
Often, developers include unnecessary sensitive data and leave filtering to the client, which can lead to serious security threats.
Unless resource-intensive requests from the client are restricted, they can degrade performance and lead to DDoS attacks.
The absence or ambiguity of policies regarding the difference between the normal and administrative levels can lead to authorization vulnerabilities.
The mass assignment vulnerability occurs when developers assign data from the client-side without properly filtering it.
Another reason where APIs can pose security risks is security misconfiguration. Among the scenarios of security misconfigurations are misconfigured HTTP headers or inappropriate HTTP methods, open cloud storage, inadequate default configurations, to mention a few.
An injection attack is conducted by sending data in the form of queries or commands to interpreters through an untrusted source. As a result, an interpreter can be tricked to reveal some sensitive data. SQL Injection is a common Injection technique.
APIs tend to expose more endpoints than traditional web applications. Therefore, it is vital to keep track of API version details and configure hosts in the proper manner.
Persistent threats in a system often go undetected for months, and investigating them, whether in-house or with external security professionals, relies heavily on log files. The lack of enough log files can not only impede threat investigation but also give the attacker an opportunity to penetrate the system undetected.
Weakness from the OWASP list above | How it shows up in a SaaS product | Control that closes it |
|---|---|---|
Broken object level authorization | Changing an ID in the request returns another tenant's record | Authorization check on every object access, tested per endpoint |
Broken user authentication | Tokens that never expire, or can be guessed or replayed | Short-lived tokens, MFA, token revocation |
Excessive data exposure | Endpoint returns full records and the client hides fields | Filter on the server, return only what the screen needs |
Lack of rate limiting | One client can exhaust capacity or brute-force logins | Per-client and per-endpoint rate limits and quotas |
Broken function level authorization | Regular users can call admin routes | Role checks enforced in the API layer, not the UI |
Security misconfiguration | Verbose errors, permissive CORS, open storage buckets | Hardened defaults, configuration scanning in the pipeline |
Improper asset management | Old API versions still reachable in production | API inventory, versioning policy, retire unused endpoints |
Insufficient logging and monitoring | Abuse goes unnoticed for months | Log every authenticated call, alert on anomalies |
Best Practices to Secure APIs:
Although the APIs do have some security issues, you shouldn’t let that deter you from taking advantage of this flexible and modular technology. Following security guidelines and implementing essential security controls can help you make the most of APIs. Here are some essential API security controls to follow:
The most basic way to improve system security is by validating users who intend to access the system. APIs do not operate independently rather they are integrated into the system. It is recommended to use multi-factor authentication instead of traditional username and password authentication.
Usually, enterprises invest a lot of their resources on the front end and ignore the importance of having a secure back end. In a properly secured back end, data is checked to prevent leakage as it leaves the system.
There are several API security tools and more continue to be introduced to the market. These tools can help with code verification and deficiencies by using pre-built security scans.
Companies always feel excited to introduce new features to their products and services. Thus, companies do not pay attention to security testing and do not allocate enough time and resources to identify vulnerabilities in new releases.
Input various operating system commands into API to check if the API is immune to injection attacks. The input commands must correspond to the operating system commands on the hosting server of API.
API-integrated web applications communicate with servers through HTTP methods like POST, GET, PUT, and DELETE. This simple task can create a system vulnerability if the server does not handle every HTTP method correctly. Although this is not the case most of the time, it can be verified by making a HEAD request to the API endpoint that requires authentication.
An enterprise that uses a DevOps philosophy and frequently releases patches for its products needs a testing tool to automate APIs security. The following are some widely used API testing tools to suit most enterprise requirements:
When you don't need this
If your product has no public or partner-facing API and every backend call comes from your own first-party client over one authenticated path, a full API security program is more than you need. Secure coding, dependency scanning and an annual penetration test cover the same ground without a separate workstream. The same applies to internal APIs that never leave a private network and carry no customer data: inventory them, log them and move on.
Dedicated API security tooling is also premature when the basics are not fixed. Buying a scanner while endpoints still return whole database rows, or tokens never expire, means paying to be told what a code review would have found. Fix authorization and data filtering in the code first.
The moment to invest is when you expose an API to customers or partners, publish documentation for it, or process personal or payment data through it. At that point the API is a product surface and deserves the same testing rigour as the login page.
Conclusion
Knowing the benefit of APIs, it is very hard to ignore them and not integrate them into your development environment. Sure, there are several security threats, but they can be addressed if you follow a few guidelines. As long as an organization implements continuous security controls and testing mechanisms along with the production of their products, they can introduce robust and safe digital products to the market.
Talk to a Cybersecurity Trusted Advisor at IRM Consulting & Advisory
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