How to Secure Online Coding Platforms

Threat Modeling for Online Coding Platforms

The evolution of DevOps teams and a greater reliance on cloud-based computing has completely changed the coding process. Now, with Integrated Development Environments (IDEs), coding can be done entirely online. This is convenient, but are online IDEs secure? To answer this, we will focus on two popular cloud-based IDEs: AWS Cloud9 and Visual Studio Online.

In online coding, the IDE is rendered inside your browser, the browser JavaScript engine uses WebSockets to initiate an Secure Shell (SSH) connection to your linked device in the background—e.g. virtual private server (VPS)—providing you with the familiar terminal interface to execute commands. The environment—meaning the linked cloud VM/VPS or SSH-accessible device—includes tool configurations (like which tokens are included, or cloud configuration files), a copy of the source code, compilers and other tools that you want to use.

The main difference between local and cloud-based coding platforms is where the bulk of the environment resides. In cloud IDEs, the environment is a virtual machine instance inside your cloud provider. In terms of security, this means you are delegating trust to the cloud provider, but you are responsible for preventing any backdoors from opening or introducing misconfiguration issues to the VM. In the case of using your own device with AWS Cloud9, you are responsible for configuring the device securely.

Linked Devices/VMs Are Not Always Secure

What is running on the backend often dictates whether linked devices and VMs are secure. As previously described, an SSH-linked device is necessary to use these online coding platforms. In the case of Visual Studio Online (still in preview mode as of this writing), we can find a Visual Studio (VS) Code server running on the machine.

The code server itself is a Node.js application to which your browser will connect. You can also download the whole ~/.vscode-remote folder and run the server inside your local environment.

As the owner of the linked device, you have permission to promote yourself to root and install or configure whatever you think you will need. You also have, by default, both Docker and Git pre-installed.

In the case of AWS-hosted Cloud9, the situation is a little more complicated. The backend necessary for platform communication is located inside the linked device while the frontend remains hosted on a different location. But, like in VS, you can also promote yourself to root.

This brings us to our first security concern: How secure or private are linked devices/VMs?

The linked device contains confidential information—access tokens, application configurations, source code, etc., which should be protected against unauthorized access.

By default, the platform is secured by the provider. However, you should keep in mind that, together with your root access availability, you are also responsible for preventing misconfiguration issues, especially when using third-party plugins. AWS does not provide plugin support for plugins not developed by them.

There are possible misconfigurations you might make that can lead to security issues. For example, if you set your IDE to be accessible from outside, either intentionally for ease of sharing, or unintentionally, that change can have major consequences.

In addition, it is not common for access tokens to be stored in encrypted token vaults. A lot of them can be viewed via plaintext configuration files. Without additional security measures, your access tokens can end up exposed to outsiders.

Once unauthorized access is acquired by cybercriminals, they can compromise your code for their own gain. An example would be the supply chain attack against a software company that modified software updates with malware.

Browsers Can Introduce Malicious Extensions or Vulnerabilities

The next security concern is the browser itself. As online coding platforms are accessed from web browsers, you should be very careful when accessing these sites from public, non-domain, shared or unprotected computers.

Malicious browser extensions are a well-known phenomenon. While an untrusted computer possibly infected with malware presents an obvious risk, it is also possible for an attacker to steal code using a malicious web browser extension.

Code Extensions and Plugins Can Also Contain Malware

The main advantage of Visual Studio Online and, generally, the VS Code platform, is the number of extensions available. This in and of itself is yet another possible attack surface.

Let’s imagine a malicious VS Code extension—a useful-looking extension with an embedded backdoor. The lack of permission checking (such as disk access, network access, process access, etc.) for extensions during installation or use, becomes a security problem. The extent of security checks during extension publishing is limited to having a valid publisher ID and a few image-related restrictions. This means you have to trust the extension developer entirely.

No Software Application Is Error-Free

The ever-present possibility of vulnerabilities in any kind of software must be considered as well. In the case of online coding platforms, they can be affected by web-class vulnerabilities since IDEs are web applications. For example, a vulnerability that allows an attacker to execute their own JavaScript code can have control of the IDE or remote linked devices.

A recent vulnerability affecting the Visual Studio Live Share extension, which is also available for VS Code, shows that we can expect to see another vulnerability affecting online coding platforms in the near future.

Securing Cloud IDEs Is a Must for DevOps

Threat modeling allows us to understand the different factors at play that can affect the overall security of a computing environment. Cloud IDEs should be no different from other software, if not more critical to secure.

Here are some recommendations for each of the security issues we raised:

• For linked device security — Install trustworthy software. Keep that software updated. Don’t indiscriminately open ports to the internet.
• For browsers — Work inside trusted and secured environments. Try to avoid using shared computers. Install browser extensions from trusted vendors only.
• For VS Code extensions — Avoid installing extensions from unknown sources or authors.
• For vulnerabilities in general — Make sure your environment is updated to the most recent version.

— David Fiser