Application logic flaws are vulnerabilities that arise from errors in designing and implementing an application’s logic. Attackers can exploit these flaws to manipulate the application in unintended ways. Including these types of application logic flaws in your technical design security testing can help identify and mitigate potential vulnerabilities early in the development process.
Here are some essential examples of application logic flaws to include in technical design security testing:
- Excessive Trust in Client-Side Controls: Assuming that client-side validation alone is sufficient to prevent malicious input. Attackers can bypass these controls by tampering with data before it reaches the server.
- Failing to Handle Unconventional Input: Not validating or sanitizing user input properly, which can lead to unexpected behavior. For example, an application might accept negative quantities for an order, which doesn’t make sense in a business context.
- Flawed Assumptions About User Behavior: Making assumptions about how users will interact with the application, which attackers can exploit. For instance, assuming users will always follow a specific workflow.
- Domain-Specific Flaws: Errors specific to the application’s domain, such as allowing unauthorized access to sensitive data or bypassing payment processing steps.
- Providing an Encryption Oracle: Allowing attackers to deduce information about the encryption key or plaintext by observing the application’s behavior.
- Email Address Parser Discrepancies: Incorrectly parsing email addresses, can lead to vulnerabilities like email injection attacks.
- Broken Two-Factor Authentication (2FA) Logic: Flaws in the implementation of 2FA that allow attackers to bypass the authentication process.
- Transaction Logic Errors: Errors in the logic that processes transactions, such as allowing transactions to be completed without proper authorization or verification.