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SecurityTrails Blog · Mar 11 · by Esteban Borges

10 Backend Security Risks and Tips on How to Prevent Them

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With modern web applications’ backends consisting of multiple servers, containers running different applications (often built from templates), and numerous software services being run, including web servers, databases, web proxies, and the like, you can see how vital it is to ensure every single part of the backend. Otherwise, your entire web application’s safety and security is at risk.

And keep in mind, most security risks occur due to misconfigurations, or even the simple lack of scanning. That’s why, in the same way that we recently explored Frontend Security Risks and Best Practices, we’re going to explore some of the most common, yet dangerous, risks within your web application’s backend security.

The complete list of backend security risks can be exhaustive, that’s why we’ve summarized some of the most common backend threats we’ve seen in the past. You’ll also find quick tips on how to prevent those. Let’s jump in.

10 Popular Backend Security Risks and How to Prevent Them

1. Data injection risks

Just as injection attacks can affect your web application’s frontend, it’s possible to perform injection attacks against your application’s backend too.

Attacks can craft queries to your web application’s backend, and if there aren’t any checks in place to verify the origin of the query, attackers can run commands directly on your backend—which in normal circumstances would have been filtered and blocked by the frontend.

Securing your backend from accepting inputs from non-authorized sources is an effective way to prevent data injection attacks.

2. Lack of authentication security

Web application backends consist of multiple services with authentication requirements, databases as well as console/OS level access have logins, and all of these services run directly on the operating system layer. Therefore, maintaining authentication security is crucial—otherwise, any vulnerability entering the system can lead to the whole operating system being compromised.

For example, when it comes to the web server, restricting logins to certain users or IP addresses, using HTTP authentication on development areas, or using automated brute force detection systems (that automatically ban offending IP addresses) helps a lot.

A frequently overlooked aspect of web applications is access control levels, commonly known as ACLs.

ACLs define what parts of a backend a team member or customer can access. Misconfigurations in this area can lead to team members or customers gaining access to sensitive parts of your web application.

We’ve seen some big data exposure issues with the cloud that began with misconfigured bucket ACLs, as seen in our article “5 AWS Misconfigurations That May Be Increasing Your Attack Surface”.

In many other cases, ACL misconfigurations could also lead to targeted attacks with team members’ systems getting compromised, and their systems in turn being used to access sensitive areas of your web application.

Ensuring that your team members and customers have just the right amount of access is important when managing your web application’s security.

4. Software misconfigurations

Your website’s frontend relies on its backend to do the heavy lifting and processing of user inputs. Consequently, any misconfigurations in the backend can result in sensitive information being presented to the user.

For example, error messages, and error handling in general, are frequently overlooked when configuring software. At times, these error messages contain sensitive information, including data paths and variable names, which can lead attackers to these files and variables directly.

Configuring the software that runs and handles your backend—including your webserver, coding language or run-time handler such as PHP—to not output sensitive error messages to the end user is highly recommended.

Another misconfiguration danger is the threat of DoS attacks. These attacks take advantage of software misconfigured with a lack of resource limitations, and attempt to exhaust system resources. Once the system resources are exhausted, the web application’s behaviour can be unpredictable, with the base operating system killing any process it sees fit.

This could cause your database to crash while keeping the web server active, or crash the web server while keeping the database active. Either scenario would result in a poor experience for your end users or customers alike.

5. Outdated/end-of-life software components

Multiple software components are used to make any web application work, with web servers, databases and other software helping to improve performance.

With all these bits of software in use, the security of each individual application has to be considered.

For example, if your web server is vulnerable, it can cause your entire web application to be vulnerable—by accepting inputs from users which can expose sensitive areas of your web application.

As we shared in our ‘Why software gets hacked’ blog post, having any outdated or end-of-life software component on the public internet is a huge risk, especially with tools like Shodan available, allowing users to search for servers running specific versions of software. This can make you and your web application an easy target when running outdated and end-of-life software.

6. Lack of vulnerability scanning

Scanning for vulnerabilities is another neglected safeguard regarding web applications, from frontend to backend. Only when you scan will you know what is and isn’t vulnerable.

Scanning is often thought of as a difficult and time consuming task, but modern tools have made it possible to scan automatically and with a low amount of effort. Using online vulnerability scanners and other tools like Nikto or OpenVAS helps you stay on top of your web application’s safety by automatically scanning and generating reports for you to review.

7. Sensitive data exposure

Applications often cache or hold data in temporary locations for customers to access. This data can be used to improve performance or simply allow users to download their files, but if data isn’t removed in time—or isn’t restricted to the specific customer—it can allow attackers to find and download this sensitive information.

For example, if a user uploads his avatar onto a web application, the web application stores it in a publicly accessible folder for the image to render. However, if the folder isn’t well secured, an attacker can locate the folder and download all the user’s avatars.

Securing folders and other publicly accessible information is a must. Also, performing self-scans by using Google Dorks enables you to quickly find public information crawled by search engines.

8. Lack of encryption between frontend and backend

Communication between your web application’s frontend and backend is what drives your web application. And this communication often goes over the internet unencrypted, as the software in use is often built without encryption in mind.

Man-in-the-middle-attacks apply not only between clients and web applications, but can also poison or steal requests from your frontend or backend, and transmit them to the attacker. While this is a more sophisticated type of attack, it’s still quite possible for someone who wishes to target your web application.

Encrypting requests between the frontend and backend is a simple yet critical solution for preventing these attacks.

9. SSL misconfigurations and lack of monitoring

Using SSL certificates has become a norm for the modern internet. Most browsers and search engines give priority to websites with SSL certificates, and display various forms of alerts and errors when browsing websites with insecure, misconfigured or expired SSL certificates.

Be sure to monitor your SSL certificate and configure it correctly. Ensuring your certificates are valid is the first step, noting that they’re set up with strong ciphers and that secure and modern TLS versions are in use on the server-side. This will go far in maintaining that your web application’s backend is communicating securely with its frontend.

10. Lack of centralized log management

With multiple backends, services and distributed servers (sometimes even across different public/private clouds and access levels), modern web applications call for a centralized logging system, to which all services can write their log files.

This allows for further monitoring and logging of errors, unauthorized entry attempts (such as failed login alerts), and other information which can be used to improve performance as well.

A lack of centralized logging often leads to unnecessary privileges being made available to team members, or simply due to the scale of things, log files getting overlooked.

This can be particularly dangerous if the log files indicate attacks against your web application’s backend, and their neglect means an attack isn’t effectively blocked in time.

Increasing your backend security with ASR

Wondering how to mitigate some of the security risks we’ve highlighted above, or where to start with securing your web application?

The SecurityTrails™ ASR tool allows you to gain visibility over many aspects of your backend security risks—by scanning the attack surface of your infrastructure and letting you know where your backend can be further secured.

ASR scans your entire organization, identifies sensitive parts of your infrastructure and helps identify other critical parts of your servers and hostnames which may be left unnoticed and open to the public, as you can see in the following video:

Take the first step, and start detecting risks before they become threats:

Today we’ve summarized some of the most popular backend security risks, and also shared tips on how to prevent those. While nowadays most of the focus is on securing a web application’s frontend, a lack of focus on the backend can lead to even greater security risks.

Remember, auditing and hardening your web application’s backend remains the best way to keep bad guys away from you.

Esteban Borges Blog Author
ESTEBAN BORGES

Esteban is a seasoned security researcher and cybersecurity specialist with over 15 years of experience. Since joining SecurityTrails in 2017 he’s been our go-to for technical server security and source intelligence info.