Are Business Logic Flaws Leaving Your APIs at Risk?

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Short answer – yes. Most application programming interface (API) attacks are not the familiar password hack or injection-based kind.

A good example is the recent Facebook hack, which exposed tens of millions of user data. In this instance, API logic allowed the exploit, and the attacker took advantage of it. It was unauthorized use of API.    

Attackers don't need to hack the API. They discover inherent business logic issues and exploit vulnerabilities like BOLA.

Are you vulnerable to business logic flaws? How can you mitigate the vulnerability with API security? Keep reading to find out.  

What are Business Logic Flaws?  

Business logic flaws are flaws in the API's design and implementation. They enable attackers to manipulate legitimate data, workflows, and functionalities to accomplish their malicious goals. These malicious goals could range from privilege escalation to the scrapping to account takeovers. 

Business logic flaws are different from other web security vulnerabilities. What distinguishes them? They are invisible to automated scanning tools. 

Logic flaws are specific to the context and often different across organizations. These flaws are also invisible to security testers unless they explicitly look for them. Attackers exploit legitimate functionalities/ processing flows to reach malicious end goals. 

Why are Business Logic Flaws Favored Targets for API Attackers?

Organizations often overlook business logic flaws. They didn't anticipate unusual user interactions with the API/ app. They may not see how users may abuse legitimate processes. As a result, attackers can easily exploit the API/app.

Further, attackers don't have to steal credentials and API keys or buy them from the black market. They don't have to crack passwords or engage in tech hacking. They simply have to abuse the logic to manipulate the API.

The API, unable to detect the malicious behavior, will respond in the way it was designed to. And this way, attackers can seamlessly bypass systems to do their bidding. 

Attack Vectors of Business Logic Flaws:

  • Failing to handle unconventional inputs
  • Putting excessive trust in client-side control
  • Flawed assumptions about user behavior
  • Authorization bypass
  • Misusing HTML elements 
  • Flaws specific to the business domain – e.g., the abuse of the discount functionality 

How to Manage the Business Logic Vulnerabilities in APIs 

Business-specific knowledge is required 

Often, attackers know how APIs function, their business logic, and what business operations they impact. They also tend to have a deeper understanding of how business logic operates in complex APIs. Even better than developers. 

Begin with the basics to ensure better API security. Understand the domain and details of the business that the API serves. You need to be up to date with changing API threat landscape. 

Think Beyond Shift Left

There has been a paradigm shift in favor of the shift-left approach to security. This approach requires organizations to incorporate security into the early stages of development. 

Business logic flaws are hard to find by parsing static code in pre-deployment stages. Unless the API is in action, you cannot find logic flaw vulnerabilities. Security should be continuous and align your product, process, and people with security.  

Security Scanners Can't Detect Logic Flaws

Relying solely on detecting misconfigurations, access control flaws, or known vulnerabilities isn't sufficient. Application security scanning tools suffer the same issues.

Security scanners are designed to find applications' weak development practices and security vulnerabilities. They miss most business logic flaws and API-related misconfigurations. 

Adopt a holistic view of API security

Treat API security as a distinct discipline and add best practices to avoid potential mistakes that often lead to attacks.

It is vital to adopt comprehensive API security solutions like AppTrana to analyze, protect and provide an adequate context for APIs. Critical capabilities include API discovery, API security testing, OWASP Top 10 API security, positive security policy, and API-specific rules. 

Every business is unique and enables unique business logic. Therefore, the tool should be fast enough to construct customer rules accordingly. It requires an understanding of the business context and underlying risks.  

Attack Simulation 

The last piece of the puzzle is to detect real-time attacks against your APIs and endpoints. The API security tool must complement experts for three reasons. 

  1. Find current vulnerabilities you were not aware of
  2. Help you to understand what logic flaws exist and how exploitable they are
  3. Eliminate false positives before you start initiating remediation actions

Create test cases that cover all possible attack scenarios. The more scenarios you test, the higher the chance of finding inherent logical flaws


Business logic flaws in APIs can be exploited with just a few minutes of trial and error. Take proactive steps to secure your business logic vulnerabilities. It helps to close gaps in your API security strategies.

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