API Attack | Meaning, Types and Prevention

You use APIs to request information from your bank, healthcare provider, and even the weather station. There’s a reason for that: most apps on your phone access databases through them. Unfortunately, threat actors could abuse them and access that same information. Therefore, understanding API attacks and how to prevent them is a must.

An API attack is the misuse or abuse of APIs to access or block data without permission. Common attacks include injections, denial of service, and mass assignments. The best way to prevent these attacks is to encrypt data, throttle traffic, and employ tokenization.

APIs often deal with sensitive information – and, at the same time, are vulnerable by design. Developers must take the time to employ API security to protect databases and users, as well as take note of the biggest API risk, which we’ll explain below.

What’s an API?

An API (short for application programming interface) connects two pieces of software. It works as a middleman between client and server, helping users make requests through it.

APIs are everywhere. More likely than not, you use dozens of them every day. In fact, the weather app that you have on your phone uses an API to get information from the National Weather Service.

Most apps use APIs in one way or another. Your healthcare provider probably has an app that uses an API to help you connect with their database. Unfortunately, that could come with a huge risk.

Biggest API Risk

APIs could be the source of a data leak, which is incredibly dangerous if we’re talking about a financial or medical app. Other seemingly-less-risky APIs can create trouble, like a smart fridge app that tracks your geolocation.

In other words, API security should be a number one priority since these interfaces work as a middleman between a company’s database and a user (who could be a threat actor).

An unsecured or poorly-secured API is the same as a door without a lock: anyone smart enough can go through it.

Hackers are happy to take a swing at an API and see what comes shaking down. An API attack could result in nothing – or a data breach that bankrupts your business.

What’s an API Attack?

An API attack takes place when a threat actor exploits an API to make it do something that is not created to do or blocks other users from accessing it.

The attempt could fail or succeed. However, the mere act of trying to abuse an API (i.e., use it for anything other than its purpose) is considered an attack.

The two most common attacks have drastically different goals: the first would end in a data breach, meaning a threat actor would steal part of or an entire database; the second would block other users from accessing it.

How Does an API Attack Happen?

Since APIs are often well documented, hackers can reverse engineer how they work, making it incredibly easy for them to find vulnerabilities to exploit.

Since this type of software requires clear-cut parameters to work, messing around with the commands you input could result in an exploit (if you don’t take the measures to prevent them).

That doesn’t mean an API is inherently vulnerable. However, developers need to take extra steps to secure them. Otherwise, a threat actor is one scan away from finding every vulnerability possible.

Websites and APIs work in a similar fashion: you have to build a fortress around them to prevent cyber criminals from injecting malicious code into it or gaining unauthorized access via privilege escalation (finding a weak link to get in and working it from there).

Types of API attacks

API/SQL Injection

Threat actors can inject malicious code into an API. It works the same way as it does in websites: a hacker could alter your API’s code to their benefit unless you set up proper defenses.

Allowing a threat actor to inject code into your API could have catastrophic consequences. It could give a hacker access to your entire database, allowing them to modify it, among other things. Under certain circumstances, it could kill the API, preventing anyone from using it.

An injection is one of the worst things that could happen to your API – and one of the most common: it’s a hacker accessing your code and changing it at will.

Broken Authorization or Authentication

Users have too many authorizations by default when using an API. In other words, they have unrestricted access to perform actions that are often out of the average user’s reach in other apps. Problems are bound to happen when developers overlook certain security measures (because APIs are relatively simple).

At the same time, threat actors could manipulate certain parameters to gain unauthorized access to information. Theoretically speaking, a hacker could change their authorization level to access data (they shouldn’t be able to get) by using different requests.

In a similar fashion, a hacker could impersonate other users if authentication is faulty or poorly implemented, making it easy for them to access every database connected to your API. Instead of changing their authorization level, they’ll simply use the API with an admin’s account (if they can find an authentication-related exploit).

Remember, this type of interface grants too many privileges to users by default, so limiting certain actions is a must before releasing an API to the public.

Data Exposure

Many API developers commit the same mistake: sharing too much information. Documenting what your API does is a great way for users to have an easy time using your app, though it leaves you wide open for threat actors to reverse engineer your code.

In other words, the more information you give out with little regard to security, the more chances threat actors have of abusing your API. It’s similar to handing out your code to help hackers see what they can exploit.

At the same time, developers often give out too much data when someone requests it, expecting users to filter it. Hackers could find valuable information in so much data. Dumping data helps threat actors employ social engineering to penetrate networks.

DDoS Attack

An API will not limit traffic in any way unless you arrange it to be that way. At first glance, that seems perfect. However, that sets your API to receive a devastating blow: threat actors could use denial of service (DoS and DDoS) attacks to neutralize your API.

Fixing this issue is simple: limit how many requests your API can take at once. That may seem like a limiting factor for users. However, you’ll hardly find regular people trying to do thousands of requests at once.

Improper Assignment

Developers often update APIs. That’s a good thing – as long as you do it correctly. Sometimes, an API version becomes deprecated, though developers won’t remove all deprecated code. In other words, you may have old, vulnerable versions of your API inside your latest, seemingly secure API.

How could that be problematic? It’s simple: more often than not, developers update their software to patch vulnerabilities. However, if the old code remains in place, those vulnerabilities are hidden, though not inaccessible.

APIs have a lot of endpoints, meaning there are a lot of places where this issue could happen.

Mass Assignment

APIs are inherently simple in nature. That’s great when you have a lot of users making a lot of requests because it’s a more efficient system. However, that allows threat actors to abuse your app.

For example, an API could assign one input to multiple properties. It’s efficient, though insecure.

A threat actor could use that to update multiple properties of their profile at the same time, such as changing their username and giving themselves admin privileges in one swift motion.

Security Misconfiguration

The way you set up your API could leave you wide open for attacks, and this time, it’s not about broken authorization or authentication – but more subtle ways of handing hackers what they want.

It could be something incredibly negligent, such as giving up sensitive information in your error messages (e.g., pathways a threat actor could use), or something smaller (though nevertheless still dangerous), like having unnecessary HTTP methods in place.

Taking the time to see how you set up your API could save you from having to go into crisis mode after a data breach takes place.

Vulnerability Exploitation

Threat actors are lightning-quick. The best in the business will find a vulnerability the same day a developer releases an app. That’s why there are so many zero-day patches nowadays.

APIs could suffer the same fate: if you don’t routinely scan your software for vulnerabilities (to patch them), hackers will do the same (to exploit them). One quick Google search will show you dozens of tools to scan for vulnerabilities. Hackers use these same tools too!

Monitoring your API to see who uses it and scanning its code to recognize vulnerabilities is the best way to prevent data breaches. At the same time, looking at the best ways to prevent an API attack is also a must.

How To Prevent an API Attack

Experts recognize APIs as a common target now, meaning you have to protect them if you want to prevent a data breach. Having a defense set up around your API means forbidding threat actors from abusing it or limiting traffic to prevent a DDoS attack.

Best ways to prevent an API attack:

  • Encryption. Hiding data from threat actors is a must, especially when it’s in transit. That means encrypting the information that a server sends to a client after a request or the one that a client sends to a server. A hacker can’t see anything if it’s properly encrypted.
  • Getaways. An API Getaway intercepts and redirects traffic. It’s a great tool to stop unauthorized users from handling sensitive data or doing any other action that could be considered an abusive practice.
  • Throttling. Placing a limit on how often an API can be called within a timeframe is a great way to prevent DDoS attacks. Establishing quotas and throttling protection is the best way to do so.
  • Tokenization. Employing access tokens is common for different software and websites, and APIs should be no exception. After a user receives authorization to use certain functions, they receive a token. A threat actor won’t be able to use (and abuse) an API without that token.
  • Vulnerability scanning. Doing routine API scans is a must to find any vulnerabilities. Prevention is the best tool to prevent data breaches. At the same time, routine checkups can also help you identify data breaches you may have overlooked.


A threat actor could abuse an API in many ways, causing a data breach or blocking other users from using it. Encryption, throttling, and tokenization, among other methods, could prevent an attack from taking place. API security should be a top priority, as hackers are targeting these applications more as time goes by.

Herman McCargo

Herman is a Microsoft Certified Security Engineer and Cybersecurity Specialist. He’s been in the technology field for over 20 years and has expertise working with the most critical technology infrastructures. He has a deep understanding of cyber risks, threat mitigation and prevention, and overseeing infrastructure.