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API security refers to the protection of APIs against attacks. Attackers are increasingly targeting APIs because they allow access to sensitive software functions, making them a prime target.
Modern web application security includes API security. APIs could have vulnerabilities such as code injection, rate limiting issues, broken authentication, authorization, or lack of rate limiting.
To identify and fix vulnerabilities in APIs, organizations should regularly test them. This article will provide various tools and methods for API security testing. It also includes a list of best practices to help you protect your APIs.
This guide is one of a series on application security.
Why is API Security Important?
API security is the protection of data that is being transferred via APIs. This typically involves data between clients and servers connected over a public network.
APIs are used by businesses to connect services and transfer information. An API that is compromised, exposed, hacked, or breached can expose financial information, personal data, and other sensitive information.
Security is an important consideration when developing RESTful APIs and other APIs.
Backend systems are susceptible to security flaws that make APIs vulnerable. An attacker could compromise API functionality and data if they compromise the API provider.
If the API isn't properly coded and protected, malicious requests can be used to exploit APIs.
For example, an attack that causes a denial-of-service (DoS) can cause an API endpoint to be taken online and significantly impact performance.
Attackers may abuse APIs by stealing data or exceeding usage limits. Advanced attackers may inject malicious code to execute unauthorized operations and compromise the backend.
Almost every enterprise application relies on APIs to perform its basic functions, thanks to the popularity of microservices or serverless architectures.
API security is now a key component of modern information security testing.
What is the difference between API Security and General Application Security?
These are the key characteristics of traditional web security.
A castle approach: The cloud network security has a clear perimeter that controls access points.
This perimeter grants or denies access to requestors and assumes that those who have entered are healthy.
Most static protocols: Incoming requests follow mostly static protocols. This allows administrators to set up a web application firewall to enforce these protocols.
Clients use a web browser: The WAF can verify the client's browser environments, and if verification fails, it assumes that the client is a bot using a headless browser or an emulator.
Analyzing requests to detect attacks: A traditional network can use a WAF in order to prevent cross-site scripting attempts (XSS) by blocking them.
The WAF can identify an attempted Distributed Delusion of Service (DDoS attack) if it observes large traffic volumes from one IP.
These are the key features of API security that set it apart from traditional security.
A castle that has many entrances but no moat: In the past, traditional networks were limited to protecting common ports such as 80 (HTTPS) and 443(HTTPS).
Many API endpoints are used by web applications today. Security can be difficult because APIs are constantly expanding.
Incoming request format that frequently changes: APIs change rapidly in a DevOps environment. Most WAFs are unable to accommodate this level.
Traditional security tools require manual tuning and reconfiguration every time an API change occurs. This is an error-prone process and takes time and resources.
Clients don't often use a browser: Most service and microservice APIs can be accessed via native and mobile apps or other software components.
These clients don't use a web browser, so browser verification is impossible for web security tools. Browser verification is often insufficient to detect malicious bots.
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API Top Security Risks
API Security Top 10 was created by the Open Web Application Security Project (OWASP) to raise awareness about the most serious API security concerns affecting organizations.
API1-2019: Object-Level Authorization Broken
Endpoints that handle object identifiers are frequently exposed through APIs. Level Access Control issues can be created by any function that accepts user input and then uses it to access data sources.
This increases the attack surface. All such functions should be subject to object-level authorization checks.
API2-2019: User Authentication Fails
Attackers frequently employ improperly implemented authentication systems. They could compromise the authentication token or exploit weaknesses in implementation to pretend they are another user.
The overall cyber security services provider of the API will be compromised if the system cannot identify the client/user.
API3-2019: exposure to data in excess
Developers often rely upon the client to filter the data before they display it to the user. This can lead to serious security problems.
Data must be filtered on the server side and should only be sent to the client side.
API4-2019: Rate Limiting and Lack of Resources
APIs don't often limit the size or number of resources that clients/users can request. This can cause a Denial of Service (DoS) and expose authentication vulnerabilities that allow brute force attacks.
API5-2019: Function-Level Authorization Broken
Overly complicated access control policies or a lack of clear separation between administrative and regular functions can often lead to authorization flaws.
Attackers can exploit these vulnerabilities to gain access or perform administrative functions.
API6-2019 Mass Assignment
Mass assignment is usually caused by binding client-provided information (i.e., JSON) to a data structure based on an allowed list but without filtering properties.
An attacker can modify object properties in many ways. They can read documentation, explore API endpoints and guess object properties. Or they can request payloads to add additional properties.
API7-2019 a security configuration error
Security misconfigurations often result from insufficient default, ad-hoc, or incomplete configurations.
API8-2019: Injection
An injection flaw, including SQL injection, NoSQL injection, and command injection, is data sent to an interpreter via a query or command from an untrusted source.
An attacker can send malicious data to fool the interpreter into performing dangerous commands or to allow the attacker to gain access to data without authorization.
API9-2019: Ineffective Asset Management
APIs are more exposed than traditional web applications and require current structured documentation. Exposure of debug endpoints or deprecated API versions may increase the attack surface.
You can mitigate this by having a list of API versions deployed and hosts properly configured.
API10-2019: Insufficient Monitoring and Logging
Insufficient monitoring and logging can be used by attackers to continue in the system, increase their hold, and extract or destroy additional data.
It takes around 200 days to find a persistent threat. Breach detection is usually done by an outside party, which highlights the importance of API monitoring.
Read More: Alert: API security will be a priority as API-based IoT attacks surge in 2020
SOAP Security vs. REST API Security
Two main architectural styles are used in modern APIs.
- SOAP--A highly structured message protocol that supports many low-level protocols.
- REST--a simplified approach to APIs that uses HTTP/S as the transport protocol and usually uses JSON format data transfer.
Both APIs handle HTTP requests and replies and Secure Sockets Layers (SSL). However, the similarities end there.
Every build will secure your app.
SOAP API security
- SOAP provides extensions to the protocol to address security issues
- SOAP is based upon W3C and OASIS recommendations.
This includes SAML tokens and XML encryption.
Signatures can also be used.
- SOAP supports Web Services (WS), which allows you to use security extensions such as WS-Security, which provides enterprise-grade security and cyber security company services.
- SOAP supports WS ReliableMessaging, which offers built-in error handling
REST security API
- REST APIs lack any built-in security features; rather, the design of the API determines its level of security.
- Data transmission, deployment, and interaction with clients must be protected.
- REST APIs don't have error handling built-in and must resend data if an error occurs.
- Common architectural choices include deploying REST APIs behind an interface gateway.
Clients connect to the gateway, which acts as a proxy and not directly to the REST API.
The API gateway can address many security concerns.
SOAP APIs are safer by design. REST APIs can still be secure depending on how they are implemented and what architecture is used.
GraphQL Security
GraphQL describes clients' query language to request information through an application programming interface (API).
Developers can use GraphQL syntax for specific data requests and to receive it from one or more sources. A client can specify the required data structure for a request, and the server will return data according to this structure.
Clients can create complex queries, and the server should be able to handle them. Servers should be capable of handling abusive queries from malicious clients and large queries from legitimate clients.
The client may take down the server if the server is unable to handle these situations properly.
These are some strategies to help you reduce security risks associated with GraphQL.
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Timeout: A timeout is a way to protect against large queries.
This strategy is the most straightforward because it doesn't require the server to have any information about the incoming queries.
The server needs to know how long each query takes.
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Maximum query level: This can prevent clients from abusing query depth.
Maximum query depth refers to analyzing the query document's abstract syntax trees (AST) to determine what is acceptable.
GraphQL can use this depth to accept or reject requests.
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Query complexity: GraphQL queries can be complex.
This is usually when some schema fields are more difficult to compute than others.
You can use query complexity to help you determine the complexity of these fields and limit queries that exceed a threshold.
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Throttling: These options can be used to stop large queries but not clients who make many small queries.
If queries are costly, even a few can be too many for GraphQL.
To throttle queries, you can calculate the time it takes to process each query type.
Methods of API Security Testing
These methods can be used to test APIs manually for security flaws.
You can test for parameter manipulation
Most API requests send parameters that can easily be manipulated. An attacker can manipulate parameters to change the purchase amount and get products free of charge or trick an API into providing sensitive data that the user doesn't authorize.
Hidden form fields are often used to tamper with parameter parameters. The browser element inspector can be used to check for hidden fields.
You can test different values to see how your API responds to hidden fields.
Check for Command Injection
You can inject operating system commands into API inputs to test whether your API is susceptible to command injection attacks.
Use the appropriate operating system commands for your API server's operating system. A harmless operating system command that you can see on the server is recommended, such as a reboot command.
An operating system command can be appended to an API URL that displays content to check if the command has been executed on the server.
Check for API Input Fuzzing
Fuzzing is when you provide random data to the API until you find a security or functional problem. Look for signs that the API returned an error or processed inputs incorrectly.
For example, if your API allows numerical inputs, you can use very large numbers, negative numbers, or zero. If your API accepts strings, you can also try random SQL queries or system commands.
Test for unhandled HTTP Methods
Different HTTP methods may be used by web applications when communicating with APIs. These HTTP methods can store, retrieve, or delete data.
You will typically get an error if your server does not support this HTTP method. This isn't always true. This creates security vulnerabilities if the HTTP method is not supported on the server side.
You can easily check if HTTP methods work on the server by sending a HEAD request through an API endpoint that requires authentication.
You can try all common HTTP methods, such as POST, GET, and PATCH.
Read More: Below are a Few Features of API that You Should Consider for Building a Secure Mobile Application
API Security Best Practices
These best practices will help you improve the security of your APIs.
Identify Vulnerabilities
Knowing which aspects of an API's lifecycle are not secure is essential. This will help you to effectively secure your API.
This can be difficult, especially if you have many APIs. You must consider the whole API lifecycle. The API should be considered a software artifact. This means it goes through every stage of a software product: planning, development, testing, staging, and production.
Leverage OAuth
Access control for authorization and authentication is a key aspect of API security. OAuth, a token-based authentication framework that permits third-party services to gain API access without exposing user credentials, is a powerful tool for controlling API access.
Encrypt data
Encrypt all data managed by an API, including personally identifiable information (PII) and sensitive data protected under compliance standards and regulations.
To ensure attackers cannot compromise your API server, implement encryption at rest and in transit with Transport Layer Security (TLS). You must require signatures to ensure that only authorized users have access to your API's data.
Throttling and Use Rate Limiting
Attackers are increasingly attracted to APIs as they gain popularity. Attackers are increasingly targeting APIs to cause denial-of-service (DoS) attacks.
You can set rate limits for API calls to prevent DoS attacks and protect against peak traffic that can impact performance and security. By regulating the number of connections, rate limiting can help balance access and availability.
Use a Service Mesh
Service mesh technology, similar to API gateways, applies different layers and management when routing requests between services.
Service mesh technology optimizes how these moving parts work together. This includes correct authentication, access control, and other security measures.
Service meshes become more important as microservices use increases. Service meshes are a key component of API management.
They can automate and secure large deployments that use multiple APIs.
Adopt a zero-trust philosophy
A perimeter traditionally surrounded networks. Elements "inside" the network was trusted while those "outside" weren't.
With insider threats increasing, networks are not as simple as they once were. Legitimate users can connect from anywhere outside the network perimeter. Public APIs allow users to access internal software components and sensitive information from anywhere in the world.
Zero trust is a security philosophy that shifts security from focusing on specific locations to particular users, assets, or resources.
This can be used to ensure APIs authenticate users and apps (whether they are within or outside the perimeter), give them the minimum privileges necessary to fulfill their roles, and closely monitors for suspicious behavior.
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Dynamic Application Security Testing (DAST) allows you to test your APIs
Bright was built with a developer's first approach to testing web applications. It focuses on API cyber security testing.
You can test legacy and modern applications with support for various API architectures.
Bright, which complements CI/CD and DevOps, empowers developers to identify and fix vulnerabilities in every build.
This reduces the reliance upon manual testing and allows them to leverage multiple discovery methods.
- HAR files
- OpenAPI (Swagger) files
- Postman Collections
You can start detecting the technical OWASP Top 10 and more.
- Bright Rest API
- Convenient CLI for developers
- Common DevOps tools such as CircleCI, Jenkins and JIRA, GitHub, Azure DevOps, and many more
