Application
The product people use, such as the intranet, the mail server or a website.
What It Is
The application is the product people actually use, such as the intranet, the mail system, an online shop or a wiki. It is the only layer most users ever see, and the reason the rest of the stack exists.
Some applications are bought, such as SharePoint, Exchange or Confluence. Others are written in-house with a framework. Either way, an application is code that the layers below it run. Those layers are usually a framework and a runtime, a web or app server, then an operating system and a machine.
Who runs it depends on how it is bought. On premises, meaning on your own servers, your team runs the application and every layer under it. With a service such as SharePoint Online, the vendor runs all of that, and you keep charge of the data, the accounts and who can see what.
- App
- Framework
- Web Server
- Runtime
- Containers
- OS
- Hypervisor
- Firmware
- Hardware
- Data
On This Layer
These are the technologies on the Application layer that this topic covers. Open one to see what it runs on, how to spot it and what a flaw in it reaches.
SharePointMicrosoft's intranet and document platform.
Exchange ServerMicrosoft's on-premises mail and calendar server.
WordPressThe web's most common content management system.
Atlassian's team wiki and documentation platform.
Atlassian's issue tracking and project tool.
GitLabA platform for Git repositories and build pipelines, often self-hosted.- MOVEit TransferA managed file transfer server for sharing files securely.
How Far a Flaw Reaches
A flaw in an application reaches its own data and whatever its service account is allowed to touch. The service account is the account the application runs as, and it can often reach more than anyone expected. The flaw does not reach the layers below by itself, though whoever gets in can use the app's account and its server as a way further in.