Statistics on market usage reveal that Node.js is now the main framework for developing web applications. For example, Node.js was adopted by Netflix as they planned to expand the capacity of their application to serve over 210 million subscribers better worldwide. 

Ensuring Node.js web application security has become a priority for organizations that have a large number of users. It’s difficult to predict how your web applications may be vulnerable to attacks. Still, you can reduce your application vulnerability risk by following Node.js backend best practices to secure it from common threats. 

That’s why we have shared some of the best Node.js security practices that you can adopt to secure your web applications. 

Netflix and Node.js Security 

Interestingly, the Node.js framework was leveraged by Netflix to improve their web application’s performance and crucially upgrade security. Netflix’s users are growing exponentially, which means they must have robust coverage for protection. 

Netflix’s Senior Platform Engineer, Guilherme Hermeto, was the one who restructured their application’s infrastructure to Node.js. The goal was to improve the debugging capabilities by using various diagnostic tools, to improve the security layers of the application. 

Our experience with Node.js has found that growth and popularity come with risks. Open-source backend networks aren’t immune to security vulnerabilities, and all Node.js developers need to know the risks cyber criminals pose to their user’s data and applications. 

To help you understand the risks of Node.js security and how to improve your web application security, we have put together tips and best practices for node.js security in this article. Read on to learn more. 

Node.js Best Practices for Improving Security

Here are the best practices for Node.js security that center around platform security, server security, data security, and application security. 

Node.js Web Application Security Best Practices:

Avoid Irregularities by Tracking Monitoring and Logging

Monitoring and logging offer you details regarding the root cause and severity of a threat. Sporadic monitoring and logging will result in security vulnerabilities, costing companies thousands of dollars. That’s why CTOs advise penetration tests frequently to detect irregularities rather than waiting for someone to report an incident. 

Voodoo, a French gaming company, is a prime example of regular logging and monitoring activities. Applications can face a threat from memory leaks, which regularly receive significant user input. Voodoo’s development team collected their application’s real-time data and metrics using the Node.js API ‘inspector.’ They managed to avoid memory leaks by regularly monitoring KPIs such as CPU consumption. 

Using Flat Promise Chains and Avoiding Nesting Layers 

One of the best features of Node.js is the asynchronous callbacks, which is a big benefit if you compare it to the basic functions for callback previously offered. However, the feature can quickly become a nightmare with increasing nesting layers. For example, if there are more than ten nesting layers, it will cause an error that could cause you to lose the results when you make the asynchronous callbacks. 

There’s a simple solution to this nesting problem, which can be resolved in the following ways:

  • Avoiding callback hell by using flat promise chains
  • Detecting exceptions and errors to increase the flow of code
  • Controlling programming semantics with flat promise chains 

Promise chaining is a syntax that allows you to chain multiple asynchronous*(not happening at the same time or together) tasks together in a particular order. It’s best suited for complex code where you must perform one asynchronous task after completing another one. 

The main idea behind flat promise chains is to ensure that if one function relies on the return value of another function’s promise return, you should return every promise value as soon as possible. Then callback and continue the logic in another, after taking the previous promises return value, which allows every statement to be as non-nested/flat as possible.  

Promise chaining takes place when the callback functions return a promise, allowing you to chain on another call, which will run when the second promise is fulfilled. That allows you to catch and handle any errors that occur along the way. 

Flat promise chains hold immense importance when you customize matchmaking requests. Callbacks are retrieved using Node.js on a single thread; it can help your team handle user requests concurrently, even at scale, with greater ease. 

Get Excellent Performance by Not Blocking the Event Loop

Even though it may seem that the Node.js event-driven, single threat architecture is under no threat when you execute JS operations that are CPU intensive, it can create some problems. Whenever your application establishes a new client connection, a response will be sent to them by the Event Loop. 

It’s not only for new connections but every outgoing and incoming request that goes through the Event Loop. When there are blocks in the Event Loop, current and new clients won’t have a chance to establish connections with the application. 

Node.js uses several small threads for handling multiple clients. In Node.js there are two types of thread: Event Loop and a Threadpool. When a thread takes a long time to execute a callback (event loop) or task (worker), it is blocked. A blocked thread works on only one client’s behalf and can’t handle requests from other clients, which affects two things, performance and security. 

When the Event Loop is blocked the performance of your server will suffer as it won’t get the throughput (requests/second), especially if you perform heavyweight activity on any thread. On top of that, security will also be compromised as malicious clients, aka hackers can submit ‘evil inputs’ to block your threads, and keep them working on one client, which would be a DOS or Denial of Service attack.  

Therefore, you should ensure you never block the Event Loop, meaning each of your JavaScript callbacks must be quickly completed. The best way to ensure this is to look at the ‘computational complexity’ of your callbacks. If your callbacks are taking a constant number of steps no matter what its arguments are, then you will always give every pending client a fair turn. If your callbacks take a different number of steps depending on its arguments, then you should think about how long the arguments may last. 

Avoid Security Loopholes by Managing Uncaught Exceptions 

Node.js terminates the entire thread and prints the current trace for uncaught exceptions. However, not all uncaught exceptions are security vulnerabilities. You can use an EventEmitter, which is a device that allows you to customize the behavior of these exceptions through Node.js. 

The EventEmitter emits the uncaughtException to the main event loop. It’s advised to bind up the uncaughtException to the event and clear unallocated resources such as file descriptors and handlers. Even if you do use the EventEmitter, there are still possibilities for errors being left within the event chain, which can cause your application to crash unexpectedly. If you want to avoid this, always show a custom error message on display for your users, instead of sharing the exact error message. 

In general, unhandled code rejections will result in security loopholes, and organizations only realize this problem when they build their applications using Node.js. Improper handlers and resource allocation over unnecessary features are the main reasons that can cause uncaught exceptions, and directly make the application vulnerable to threats. To deal with all uncaughtExceptions, you should use the command “triggerUncaughtException” to alert the developers and determine errors within your programming syntax in real-time. 

Node.js Data Security

Prevent Unauthorized Attacks by Handling Errors

To prevent unauthorized attacks and ensure that your application functions steadily, you must handle errors quickly. Your application may leak or display sensitive information such as stack traces to your clients during an error. When cybercriminals know that your application is vulnerable, they will send repeat requests and try to crash the application. 

Uber, the geospatial application that operates in real-time, protects itself from this scenario by sending constant road mapping and matchmaking notifications to its users and drivers. Using notifications, they countered the repeat requests from hackers trying to crash the application and made connections easier for their customers. 

Besides correct analysis for errors, the Node.js framework also allowed faster deployment for code, which ensured the Uber application was secure from false requests sent constantly. Uber learned that handling errors in Node.js is extremely quick and easy, as it can get help from external tools and internal components to prevent unauthorized attacks. 

Server Security

Avoid DOS Attacks by Limited Size of Requests 

One of the biggest Node.js security concerns is to ensure that you use limited size of requests, ensuring you can thwart any attacks with large bodies of requests. The bigger your payload, the more difficult it will be to process the request by a single thread. 

Hackers rely on Denial-of-Service (DOS) attacks where they send requests in large numbers to a network or machine. Their goal is to ensure the intended users can’t access the application. By flooding their intended target with information or traffic, they can crash the application, fill up desk space, and drain server memory, resulting in a Denial of Service. 

High-profile organizations like commerce, media, and banking companies, or trade and government organizations are the most common victims of DOS attacks. Even though these attacks may not result in the loss or theft of sensitive data or information, they can cost their victims a lot of time and money to recover. At the same time, their reputation in their industry may be compromised. 

A Denial of Service or DOS attack would be a massive disappointed for your users, and would be a massive security threat for your application. Therefore, you must take it seriously, and limit the request size by using raw-body, external tools such as ELB, and firewall. You can also configure express body-parser to accept small-size payloads. Requesting size limits for specific content types using express middleware and validating the data against the content type stated in the request headers can help you avoid DOS attacks as well. 

Manage Sessions by Setting Up Cookie Flags

Setting up cookie flags and session management is a crucial aspect of Node.js web application security that can’t be overlooked. Any information related to session management for web applications is shared through cookies. Session cookies save the user session information once the user has logged into the web application. 

This information is extremely sensitive and may contain profile data, a login token, or even behavioral data that explains users’ preferences on your app. If hackers get access to these session’s cookies, they can easily impersonate their victim. Setting up cookie flags is the best option to ensure they aren’t readable in clear text. 

On the other hand, session hijacking remains the most prevalent risk facing user session management. Sessions are like the users’ passports or driver’s licenses using your web application. For example, when a hacker steals a user’s session, they can access all their data, allowing them to use it for nefarious purposes. They can assume the identity of that user to perform malicious activities in their name or, even worse, exploit the user. 

Web browsers that support the ‘secure flag’ will only send cookies with a ‘secure flag’ request next to them. That means browsers won’t send cookies with ‘secure flags’ over an unencrypted channel. 

The risk is even bigger when they can compromise the website admin’s identity, as they will have access to more privileges by stealing their session. That’s why setting up cookie ‘secure flags’ in Node.js is of paramount importance when discussing how to secure Node.js web applications. 

Platform Security 

Ensure You Have Up-to-Date Packages

If you want the latest security updates, you should ensure that all packages from third parties are kept up-to-date, regardless of what frame you are using. Regularly updating your packages in Node.js allows you to project fast, secure, and enjoy the cutting-edge features of all your dependencies. 

You should update packages at least once every two months, so you don’t have breaking changes, and can control any changes introduced much better. Your packages also get frequent updates and upgrades with bug fixes, security patches, and new features.

However, these open-source packages, specifically NPM, are the main contributors to Node.js security vulnerabilities, even though they are incredibly helpful. A standard Node.js web application consumes hundreds or thousands of these NPM packages, but the security risk caused by them is often brushed aside. Most open-source packages allow new ports to be opened, increasing the attack surface. 

Nearly 80% of Node.js shops use vulnerable packages, which is an ominously high percentage. Open-source packages also grow stale regularly because their security flaws remain unfixed. If you use NPM packages, you will inevitably face security threats. 

The best method is to ensure you’re always using up-to-date packages. You must always be aware of any third-party applications in the Node.js framework and keep tabs on security developments and problems from bulletins. 

Maintain Application Stability by Not Using Dangerous Functions

It’s well-known that specific modules and functions within the Node.js framework are thought to be ‘dangerous’ functions, since can seriously compromise the application’s platform security. The two main dangerous functions that all experts warn against are the Child Process function and Eval function

In general, Node.js enables non-blocking, single-threaded performance, but if you run a single thread, a CPU can’t handle the increased workload, which is where a child process module is used to create new child processes. These child processes communicate using a messaging system built into their framework. However, child processes are also vulnerable to attacks from hackers, who can easily manipulate it by sending messages and gaining access to the framework. 

Experts consider the Eval function dangerous while running on Node.js web applications mainly because it shares the caller’s privileges when the code is executed with the Eval function. So, if you’re running the eval function with a string, a malicious party can affect it, which would result in you running malicious code on the user’s machine with your webpage/extension’s permissions. 

Keeping the functions aside, you should watch your modules since they can pose security threats. Some of these functions and modules include setImmediate function, setInterval function, execScript, setTimeout function, VM module. 

Use SAST and Security Liners for Methodological Testing 

You can’t possibly track all the vulnerabilities and ensure that you have a secure Node.js application. Therefore, it’s natural to overlook some incorrect code, function, or component vulnerabilities. That’s the reason organizations employ analytical testing methodologies to identify and scan programming errors that may result in security breaches. 

Organizations commonly implement a scanning facility and security testing for centralized applications. However, most of these centralized testing facilities don’t offer developers much help to identify security threats when programming in real-time. Microblogging websites such as Twitter have tried overcoming this problem by adopting self-service scanning. 

They use the SAST method, allowing developers to control their programming syntax. Static Application Security Testing or SAST is a set of technologies designed to analyze the source code of an application, along with its binaries and byte code. It is mainly used in circumstances where there signs of security vulnerabilities during designing and coding a software or application.  

SAST should generally be used early in the software development life cycle (SDLC) since it can be done without executing code and doesn’t require a working application. It’s an incredibly beneficial tool for developers, and helps them identify vulnerabilities in the initial development stages. It aids developers in resolving issues quickly without passing on vulnerabilities or breaking builds before the application is released to the general public. 

SAST tools give real-time feedback to developers as they code, allowing them to fix issues before passing the code to the next phase of the SDLC. That prevents security threats as you get graphical representations of any vulnerabilities from source to sink. That ensures easier navigation of the code while you get in-depth guidance on fixing vulnerabilities and the best places in the code for fixing them without needing expertise in domain security.