Many current web or mobile apps utilize an application programming interface (API) on the back end. APIs serve as a collection of tools and protocols that allow developers to offer flexibility and scalability in front-end applications. They are a great way to establish connections with partners, systems, and other developers. Since APIs form the back end of client-facing applications, ensuring their security is vital for protecting users and connected systems.

APIs can be either public or private. Private APIs are used only for specific, dedicated client applications. However, private APIs do not provide any additional security. Client applications can be reverse engineered and popular front-end technologies like JavaScript make it easy for hackers to discover and abuse APIs.

The primary security concerns for APIs are with authentication and authorization of users.

  • Authentication is what determines the identity of a user and confirms if a user is who s/he claims to be.
  • Authorization is what determines the functions, data, and/or folders a particular user is allowed access to.

Both authentication and authorization pose major security challenges. Just as you cannot rely on client applications for API access, you also can’t fully trust the identities of users connecting to your systems. Applications are often at risk of brute force attacks such as credential stuffing, session stealing, and other types of impersonation of legitimate users. Account takeover (ATO) is frequently the initial step in an attack on a system. It is also a common way to access authenticated API services, especially with the numerous data breaches in recent years and many people’s tendency to reuse passwords. Therefore, these two activities need extra layers of security.

In addition to attacks on user identity , APIs are also vulnerable to injection attacks like SQL injection or remote command execution attacks, which enable hackers to basically take over the entire system for their own purposes.

To secure APIs and the web applications that use them, it is critical that developers follow secure coding guidelines, use robust application security testing tools, and runtime application self-protection (RASP) to identify vulnerabilities and prevent exploitation of those vulnerabilities that do exist.