What Are API Security Threats?

Application programming interfaces (APIs) are essential components of modern software applications. By enabling databases, applications, and platforms to communicate with each other and exchange information, APIs are essential to properly functioning digital ecosystems. They also have access to or transmit vast amounts of sensitive data. These facts have made APIs a highly popular attack vector for cybercriminals — and have made preventing API security threats a high priority for CISOs.

APIs define rules and protocols that enable applications to communicate and share data with other systems. This interconnectedness enables developers to build apps that leverage the functionality and services of existing applications, rather than having to re-create those functions and services from scratch with each new build. As a result, APIs accelerate software development and enable innovation, collaboration, and automation.

Explosive growth in the use of APIs has given rise to increasingly potent API security threats. Because APIs often enable critical functionality, they are attractive targets for threat actors who want to disrupt businesses. APIs may also expose endpoints that, when not properly secured, can be exploited to gain access to an application’s data and services or to a broader IT environment. Additionally, APIs handle large amounts of personally identifiable information (PII), financial data, and other sensitive information. The increasing reliance on APIs in modern apps and microservices architecture has created a new and broad attack surface, with a growing number of opportunities for malicious actors to exploit vulnerabilities in API code.

API security solutions help defend APIs from cyberthreats and vulnerabilities to protect confidential information and ensure the availability of the data and services that APIs provide. API security encompasses multiple layers of protection that typically include authentication, authorization, validation, and encryption to protect API endpoints.

By successfully defending against a wide range of API security threats, organizations can prevent a potentially devastating attack and achieve critical cybersecurity objectives.

• Protecting sensitive data: APIs often handle a great deal of sensitive information. Superior API security helps avoid security breaches that expose sensitive user data and PII, and helps prevent attackers from gaining unauthorized access to applications and IT systems.

• Maintaining trust: A data breach can significantly damage an organization’s reputation, causing a loss of trust and loss of business opportunities. Secure APIs help maintain the trust of users, customers, and partners by safeguarding their data and ensuring the reliability of services.

• Ensuring compliance: Many industries are subject to regulatory requirements that mandate the protection of sensitive data. Secure APIs help organizations comply with these regulations and avoid legal penalties and fines.

• Preventing service disruptions: Cybercriminals often target APIs as part of denial-of-service (DoS) attacks and other disruptions that can affect the availability of services for users and customers. Ensuring the security of APIs is critical for maintaining business operations and productivity.

There are many different types of API security threats. The OWASP API Security Top 10 is a list of the most dangerous API security threats as determined by the Open Worldwide Application Security Project. These and other threats exploit a variety of API security issues.

Authentication is the process of ensuring that a user, device, or application trying to access an API is really who or what it claims to be. Authorization determines what an authenticated entity is allowed to do with the API. Attackers may exploit weaknesses in authentication protocols or bypass authorization checks to gain unauthorized access to the API. This is called API abuse or business logic abuse and can lead to data breaches, unauthorized transactions, or other malicious activities. Types of API security threats in this area include:

• Broken authentication: Weak or misconfigured authentication mechanisms can allow attackers to impersonate legitimate users.

• Broken object-level authorization: Failing to properly enforce access control can allow unauthorized users to access or modify sensitive data.

• Broken object property-level authorization: This threat involves unauthorized access to specific properties of an object.

With these API security threats, attackers get APIs to return excessive or improperly masked data, enabling hackers to extract sensitive information by analyzing API responses. These API security threats include:

• Excessive data exposure: APIs may return more data than necessary, increasing the risk of exposing sensitive information.

• Insufficient data masking: Failing to properly mask sensitive data, such as PII, can lead to data breaches.

In an injection attack, attackers craft API requests that include malicious code to exploit vulnerabilities in how an API processes inputs. When the back-end system executes the code, attackers may be able to gain unauthorized access, manipulate data, or perform other harmful actions. Injection attacks include:

• SQL injection: Inserting malicious SQL queries into API requests to manipulate or access the database.

• Command injection: Executing arbitrary commands on the server by injecting malicious code into API requests.

DoS attacks and distributed denial-of-service or DDoS attacks send a large number of requests to an API in a short period of time, overwhelming the API’s capacity to handle them. As a result, the API may crash or slow down and become unavailable to legitimate users.

This category of API security threats allow attackers to take advantage of incorrect or insecure configurations of the API and its environment. By exploiting these misconfigurations, hackers may gain unauthorized access, escalate privileges, or compromise the system. Common targets include insecure endpoints, exposed debugging information, and unpatched API vulnerabilities.

• Insecure default configurations: These attacks exploit default settings that are not secure.

• Incomplete configurations: These attacks take advantage of a failure to properly configure security settings.

In MITM attacks, hackers intercept communication between the client and the API to steal sensitive information, manipulate data, or inject malicious code into the communication stream. MITM attacks may take advantage of:

• Lack of encryption: Failing to encrypt data in transit makes it easier for attackers to intercept and read the data.

• Weak encryption: Using outdated or weak encryption protocols.

Threat actors often use social engineering techniques to obtain legitimate credentials and access privileged API keys. This allows them to log in posing as a legitimate user or administrator to access an API. Alternately, attackers may use brute-force attacks to repeatedly guess passwords until a working combination is found.

Attackers may abuse or misuse APIs by exploiting flaws that produce unintended or malicious behaviors or outcomes. With server-side request forgery (SSRF), for example, an attacker manipulates an API to make unauthorized requests to internal systems. This can lead to unauthorized access to internal services and data breaches, which can often result in large-scale, costly data-scraping attacks.

Teams defending their organization against API security threats must overcome a number of challenges.

• Lack of visibility: APIs often exist within complex ecosystems that include multiple services, third-party integrations, and microservices. When open-source and third-party APIs are added to this mix, security teams frequently have a hard time identifying and inventorying all the APIs in their digital footprint, let alone securing them.

• Real-time requirements: APIs must frequently handle requests in real time, making it difficult to implement security measures that can introduce latency.

• Rapid proliferation and API sprawl: In many organizations, APIs are developed at a rapid pace by multiple teams, often without a central framework for governing or securing APIs. This makes it difficult to ensure consistent security across various platforms.

• Rapid development cycles: The rapid development cycles of modern software development can lead to security being overlooked. Continuous integration and continuous deployment (CI/CD) pipelines may not have the proper security testing to ensure that vulnerabilities are properly addressed.

To successfully mitigate API security threats, organizations are wise to adopt multiple security measures.

• Strong authentication and authorization: Using strong authentication methods, such as OAuth and multi-factor authentication (MFA), can help ensure that only authorized users can access the API. Implementing function-level authorization and broken object-level authorization checks can prevent unauthorized access to sensitive data.

• Real-time traffic analysis: Analyzing the behavior of API traffic is critical to ensuring that APIs are protected, because even an API operating within correct parameters can be abused. Traffic analysis looks at changes in API behavior that differ from a baseline expectation, like an API call that originated in one country and then originated from a different country an hour later.  

• Robust API testing: Assessing an API for vulnerabilities before putting it into production is a way to protect the API lifecycle before problems even begin. This practice helps developers keep pace with innovation without potentially compromising the security of the APIs supporting that innovation.   

• API gateways: An API gateway serves as the entry point for all API requests, managing tasks like authentication, rate limiting, traffic management, and caching to prevent DDoS attacks in real time.

• Rate limiting and throttling: Rate limiting and throttling can help prevent DoS and DDoS attacks by limiting the number of requests an API can handle in a given time period. This ensures that the API remains available to legitimate users even under high-traffic conditions.

• Input validation: Validating all input data can prevent many common attacks, such as SQL injection and excessive data exposure. Ensuring that only valid and expected data is processed by the API can reduce the risk of security vulnerabilities.

• Use secure communication: Using Transport Layer Security (TLS) to encrypt data in transit can help protect sensitive information from being intercepted by attackers. Ensuring that all communication between clients and APIs is encrypted is essential for maintaining data confidentiality and integrity.

• Regular audits and API security testing: Conducting regular security audits and testing can help identify and address vulnerabilities before they can be exploited by attackers. Automated security testing tools can be integrated into the CI/CD pipeline to ensure continuous security monitoring.

• API management and gateway solutions: Using API management and gateway solutions can provide centralized control over API security. These tools can help enforce security policies, monitor API usage, and detect potential security threats.

• Implement Zero Trust architecture: Adopting a Zero Trust security model ensures that no user or device is trusted by default, regardless of their location. Continuous verification of identities and permissions helps ensure that only authorized users can access APIs.

• Use web application firewalls (WAFs): Web application firewalls can help protect APIs from common web-based attacks, such as SQL injection and cross-site scripting (XSS). WAFs can be configured to block malicious requests and provide an additional layer of security.

In addition to implementing specific API security solutions, organizations can improve API security by adhering to these best practices.

• Follow OWASP guidelines: The Open Worldwide Application Security Project (OWASP) provides comprehensive guidelines for securing APIs. The OWASP API Security Top 10 highlights the most critical API security risks and provides recommendations for mitigating them.

• Secure API endpoints: Ensuring that all API endpoints are properly secured with authentication and authorization checks can help prevent unauthorized access. Implementing proper access control measures and regularly reviewing endpoint configurations can enhance security.

• Use JSON Web Tokens (JWTs): Using JSON Web Tokens for secure data exchange can help ensure that API requests are authenticated and authorized. JWTs provide a secure way to transmit information between parties and can be used to verify the integrity and authenticity of API requests.

• Monitor API behavior: Monitoring API behavior helps detect unusual or suspicious activity that may indicate a security threat. Implementing logging and monitoring solutions can provide visibility into API traffic and help identify potential security incidents.

• Educate developers: Educating developers about API security best practices and incorporating security into the API development process with API testing can help prevent security vulnerabilities. Providing training and resources on secure coding practices can enhance the overall security of APIs.

• Automate security measures: Automation helps ensure consistent application of security measures across the API lifecycle. Automated tools can be used for security testing, monitoring, and enforcing security policies to reduce the likelihood of human error.

• Protect API keys: API keys, which are identifiers that authenticate API requests, can be exposed if not properly secured. Using MFA and securely storing API keys can help protect them from unauthorized access.

• Mitigate bots: Malicious bots can exploit APIs to perform automated cyberattacks, such as credential stuffing or scraping sensitive data. Implementing bot mitigation strategies and monitoring API traffic can help detect and prevent such activities.