Disable external process commands in HTTP + On-Behalf-Of mode #1522

anuchandy · 2026-01-20T02:45:53Z

What does this PR do?

External process commands (like azqr) use IExternalProcessService to spawn local processes. In HTTP + OBO mode, this is a security risk: processes run under the server's host identity (not the OBO user's context), and malicious requests could exhaust server resources.

Add IsHttpOnBehalfOfMode() method to ServiceStartOptions
Conditionally exclude AzqrCommand registration in ExtensionSetup

Fixes #1521

[Any additional context, screenshots, or information that helps reviewers]

GitHub issue number?

[Link to the GitHub issue this PR addresses]

Pre-merge Checklist

Copilot

Pull request overview

This PR implements a security enhancement to disable external process commands (specifically azqr) when the MCP server is running in HTTP mode with On-Behalf-Of authentication. This prevents security risks where spawned processes would execute under the server's host identity rather than the user's context.

Changes:

Added IsHttpOnBehalfOfMode() helper method to ServiceStartOptions to detect HTTP + OBO mode
Implemented conditional registration logic in ExtensionSetup to exclude AzqrCommand in HTTP + OBO scenarios
Updated changelog to document the security enhancement

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
core/Azure.Mcp.Core/src/Areas/Server/Options/ServiceStartOptions.cs	Adds helper method to detect HTTP + On-Behalf-Of mode
tools/Azure.Mcp.Tools.Extension/src/ExtensionSetup.cs	Implements conditional registration to exclude azqr command in HTTP + OBO mode
servers/Azure.Mcp.Server/changelog-entries/1768876346795.yaml	Documents the security feature addition

Copilot · 2026-01-20T02:55:00Z

core/Azure.Mcp.Core/src/Areas/Server/Options/ServiceStartOptions.cs

+    public bool IsHttpOnBehalfOfMode()
+    {
+        return Transport == TransportTypes.Http
+            && OutgoingAuthStrategy == OutgoingAuthStrategy.UseOnBehalfOf;
+    }


The new method IsHttpOnBehalfOfMode() and the conditional registration logic in ExtensionSetup lack test coverage. Consider adding unit tests to verify:

IsHttpOnBehalfOfMode() returns true when Transport is Http and OutgoingAuthStrategy is UseOnBehalfOf

IsHttpOnBehalfOfMode() returns false for other combinations (stdio transport, different auth strategies, etc.)

ShouldExposeExternalProcessCommands() correctly excludes azqr command registration when in HTTP + OBO mode

ShouldExposeExternalProcessCommands() allows azqr command registration when ServiceStartOptions is null or not in HTTP + OBO mode

These tests would help ensure the security fix works as intended and prevent regressions.

Sounds like some good things to practice with having GitHub Copilot CLI or MCP server tools within VS Code follow.

vukelich · 2026-01-22T22:36:36Z

core/Azure.Mcp.Core/src/Areas/Server/Options/ServiceStartOptions.cs

+    /// Determines whether the server is running in HTTP mode with On-Behalf-Of authentication.
+    /// </summary>
+    /// <returns>True if running in HTTP transport with On-Behalf-Of authentication; false otherwise.</returns>
+    public bool IsHttpOnBehalfOfMode()


Subjective style: this can be a property which looks a subjectively cleaner with c# syntax.

[JsonIgnore] public bool IsHttpOnBehalfOfMode => Transport == TransportTypes.Http && OutgoingAuthStrategy == OutgoingAuthStrategy.UseOnBehalfOf;

At the end of the day, both are creating parameterless methods.

Thanks - yes, that’s actually what Copilot suggested. I was thinking it could be a method since we’re "computing" a boolean (coming from a Java mindset), but let’s go with a property given that’s more idiomatic.

C# properties are a hybrid between fields and methods. While writing code, they can be referenced using field-like syntax (i.e., usage infers reading vs writing), but during compilation, they are translated into methods.

vukelich · 2026-01-22T22:37:32Z

core/Azure.Mcp.Core/src/Areas/Server/Options/ServiceStartOptions.cs

+    public bool IsHttpOnBehalfOfMode()
+    {
+        return Transport == TransportTypes.Http
+            && OutgoingAuthStrategy == OutgoingAuthStrategy.UseOnBehalfOf;
+    }


Sounds like some good things to practice with having GitHub Copilot CLI or MCP server tools within VS Code follow.

vukelich · 2026-01-22T22:39:30Z

tools/Azure.Mcp.Tools.Extension/src/ExtensionSetup.cs

        var extension = new CommandGroup(Name, "Extension commands for additional Azure tooling functionality. Includes running Azure Quick Review (azqr) commands directly from the MCP server to get service recommendations, generating Azure CLI commands from user intent, and getting installation instructions for Azure CLI, Azure Developer CLI and Azure Core Function Tools CLI.", Title);

        // Azure CLI and Azure Developer CLI tools are hidden
        // extension.AddCommand("az", new AzCommand(loggerFactory.CreateLogger<AzCommand>()));


I'd recommend removing this comment OR putting it into the new if block body related to external process commands. If it returns, I suspect we'd want it guarded by the same logic.

vukelich · 2026-01-22T22:42:34Z

tools/Azure.Mcp.Tools.Extension/src/ExtensionSetup.cs

+    {
+        ServiceStartOptions? startOptions = serviceProvider.GetService<ServiceStartOptions>();
+
+        if (startOptions is null)


If you want some modern C# null variable checking syntactic sugar:

if (serviceProvider.GetService<ServiceStartOptions>() is ServiceStartOptions startOptions) { return !startOptions.IsHttpOnBehalfOfMode(); } return true/whateverDefault;

Totally optional. Current code is fine. Just teaching.

thanks, will use type pattern matching here

vukelich · 2026-01-22T22:48:06Z

tools/Azure.Mcp.Tools.Extension/src/ExtensionSetup.cs


    public CommandGroup RegisterCommands(IServiceProvider serviceProvider)
    {
        var extension = new CommandGroup(Name, "Extension commands for additional Azure tooling functionality. Includes running Azure Quick Review (azqr) commands directly from the MCP server to get service recommendations, generating Azure CLI commands from user intent, and getting installation instructions for Azure CLI, Azure Developer CLI and Azure Core Function Tools CLI.", Title);


Will this message need to be updated to exclude azqr if we don't add it below?

vukelich · 2026-01-22T23:00:59Z

tools/Azure.Mcp.Tools.Extension/src/ExtensionSetup.cs

+
+        if (startOptions is null)
+        {
+            // First container (CLI routing) - startOptions not available, allow all commands


First container

Now, I know what this means, but I doubt anyone else would. Please reference the Program.cs files in the servers folder where the multiple containers are detailed. Ugly for now, but referencing that design complexity in a cleaner way is out of scope for this PR.

Good point - yes, the multi-container setup is pretty confusing :). Let me link to the entry point / program.cs where that is happening.

Disable external process commands in HTTP + On-Behalf-Of mode

a1c8148

anuchandy self-assigned this Jan 20, 2026

anuchandy requested a review from wbreza as a code owner January 20, 2026 02:45

Copilot AI review requested due to automatic review settings January 20, 2026 02:45

anuchandy requested review from a team and jongio as code owners January 20, 2026 02:45

anuchandy requested review from KarishmaGhiya, chidozieononiwu, hallipr, jairmyree and vukelich January 20, 2026 02:45

github-project-automation bot added this to Azure MCP Server Jan 20, 2026

github-project-automation bot moved this to Untriaged in Azure MCP Server Jan 20, 2026

github-actions bot added the tools-Azd Azure Developer CLI related label Jan 20, 2026

Copilot started reviewing on behalf of anuchandy January 20, 2026 02:46 View session

Copilot AI reviewed Jan 20, 2026

View reviewed changes

anuchandy added remote-mcp and removed tools-Azd Azure Developer CLI related labels Jan 20, 2026

joshfree moved this from Untriaged to In Progress in Azure MCP Server Jan 20, 2026

joshfree added this to the 2026-01 milestone Jan 20, 2026

vukelich approved these changes Jan 22, 2026

View reviewed changes

Disable external process commands in HTTP + On-Behalf-Of mode #1522

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anuchandy commented Jan 20, 2026

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vukelich Jan 22, 2026 •

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