What practical steps would you take to reduce the runtime privileges and attack surface of an ASP.NET Core container?

Run .NET containers as non-root with minimal privileges

Reduces container privileges through non-root execution, minimal images, controlled filesystems, and explicit capability requirements.

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The image creates or uses a dedicated application user, copies published files with correct ownership, and listens on an unprivileged port such as 8080. Writable paths are explicit for temporary files or caches, while the application directory can remain read-only. I prefer a supported minimal runtime base and keep shells, compilers, and package managers out of the final stage unless an operational need justifies them.

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Non-root users, privileged ports, filesystem permissions, read-only roots, Linux capabilities, minimal bases, package managers, and runtime needs.

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I would run the application as a non-root user and give it only the filesystem and network permissions it actually needs. A container boundary does not make root inside the container harmless.
The image creates or uses a dedicated application user, copies published files with correct ownership, and listens on an unprivileged port such as 8080. Writable paths are explicit for temporary files or caches, while the application directory can remain read-only. I prefer a supported minimal runtime base and keep shells, compilers, and package managers out of the final stage unless an operational need justifies them.
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At deployment I drop unnecessary Linux capabilities, prevent privilege escalation, and use a read-only root filesystem where the application supports it. Temporary storage can be mounted separately with size limits. TLS private keys, diagnostics sockets, and certificate stores need deliberate permissions; loosening the whole filesystem to make one feature work is not acceptable. Debug tooling belongs in a controlled diagnostic image or ephemeral workflow, not every production image.

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Running as root because the host is isolated.
Using chmod 777 to fix one permission error.
Installing diagnostic tools in every runtime image.
Assuming a minimal image removes the need for patching.

What practical steps would you take to reduce the runtime privileges and attack surface of an ASP.NET Core container?

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