DllSpy

Scans compiled .NET assemblies to discover input surfaces (HTTP endpoints, SignalR hubs, WCF services, gRPC services, Razor Pages, Blazor components, Azure Functions, OData endpoints), check authorization configuration, and flag security issues — all without running the application.

Available as a CLI tool and a PowerShell module.

Installation

CLI

dotnet tool install -g DllSpy

PowerShell

Install-Module -Name DllSpy

Usage

CLI

# List all surfaces
dllspy ./MyApi.dll

# Scan for security vulnerabilities
dllspy ./MyApi.dll -s

# Filter by surface type (HttpEndpoint, SignalRMethod, WcfOperation, GrpcOperation, RazorPage, BlazorComponent, AzureFunction, ODataEndpoint)
dllspy ./MyApi.dll -t HttpEndpoint

# Filter by HTTP method and class name
dllspy ./MyApi.dll -m DELETE -c User*

# Only authenticated / anonymous surfaces
dllspy ./MyApi.dll --auth
dllspy ./MyApi.dll --anon

# Only scan host (runnable) assemblies, skip class libraries
dllspy ./MyApi.dll --host-only

# Scan with minimum severity
dllspy ./MyApi.dll -s --min-severity High

# Output format: table (default), tsv, json
dllspy ./MyApi.dll -o json
dllspy ./MyApi.dll -o tsv

JSON + jq

# List all unprotected routes
dllspy ./MyApi.dll -o json | jq '[.[] | select(.requiresAuthorization == false) | .displayRoute]'

# Count surfaces by type
dllspy ./MyApi.dll -o json | jq 'group_by(.surfaceType) | map({type: .[0].surfaceType, count: length})'

# Security issues as compact table
dllspy ./MyApi.dll -s -o json | jq -r '.[] | [.severity, .surfaceRoute, .title] | @tsv'

PowerShell

# All surfaces
Search-DllSpy -Path .\MyApi.dll

# Filter by surface type
Search-DllSpy -Path .\MyApi.dll -Type HttpEndpoint
Search-DllSpy -Path .\MyApi.dll -Type SignalRMethod
Search-DllSpy -Path .\MyApi.dll -Type WcfOperation
Search-DllSpy -Path .\MyApi.dll -Type GrpcOperation
Search-DllSpy -Path .\MyApi.dll -Type RazorPage
Search-DllSpy -Path .\MyApi.dll -Type BlazorComponent
Search-DllSpy -Path .\MyApi.dll -Type AzureFunction
Search-DllSpy -Path .\MyApi.dll -Type ODataEndpoint

# Filter by HTTP method
Search-DllSpy -Path .\MyApi.dll -HttpMethod DELETE

# Filter by class name (supports wildcards)
Search-DllSpy -Path .\MyApi.dll -Class User*

# Only authenticated / anonymous surfaces
Search-DllSpy -Path .\MyApi.dll -RequiresAuth
Search-DllSpy -Path .\MyApi.dll -AllowAnonymous

# Only scan host (runnable) assemblies, skip class libraries
Search-DllSpy -Path .\bin\*.dll -HostOnly

# Find security issues
Test-DllSpy -Path .\MyApi.dll

# Only high-severity issues
Test-DllSpy -Path .\MyApi.dll -MinimumSeverity High

# Only scan host assemblies for security issues
Test-DllSpy -Path .\bin\*.dll -HostOnly

# Detailed view
Test-DllSpy -Path .\MyApi.dll | Format-List

Supported Frameworks

Framework	Detection Method	Surface Type
ASP.NET Core / Web API	Controller base class, [ApiController], naming convention	HttpEndpoint
SignalR	Hub / Hub<T> inheritance	SignalRMethod
WCF	[ServiceContract] interfaces + [OperationContract] methods	WcfOperation
gRPC	Generated base class with BindService	GrpcOperation
Razor Pages	PageModel inheritance, On{Verb}[Handler][Async] methods	RazorPage
Blazor	ComponentBase inheritance + [Route] attribute	BlazorComponent
Azure Functions	[FunctionName] / [Function] + [HttpTrigger] parameter	AzureFunction
OData	ODataController inheritance	ODataEndpoint

Security Rules

HTTP Endpoints

Severity	Rule	Description
High	Unauthenticated state-changing endpoint	DELETE, POST, PUT, or PATCH without [Authorize]
Medium	Missing authorization declaration	Endpoint has neither [Authorize] nor [AllowAnonymous]
Low	Authorize without role/policy	[Authorize] present but no Roles or Policy specified

SignalR Hub Methods

Severity	Rule	Description
High	Unauthenticated hub method	Hub method without [Authorize] (directly invocable by clients)
Low	Authorize without role/policy	[Authorize] present but no Roles or Policy specified

WCF Operations

Severity	Rule	Description
High	Unauthenticated WCF operation	Operation without [PrincipalPermission] or [Authorize]
Low	Authorize without role	[PrincipalPermission] present but no Role specified

gRPC Operations

Severity	Rule	Description
High	Unauthenticated gRPC operation	Service method without [Authorize]
Low	Authorize without role/policy	[Authorize] present but no Roles or Policy specified

Razor Page Handlers

Severity	Rule	Description
High	Unauthenticated state-changing handler	POST, PUT, DELETE, or PATCH handler without [Authorize]
Medium	Missing authorization declaration	Handler has neither [Authorize] nor [AllowAnonymous]
Low	Authorize without role/policy	[Authorize] present but no Roles or Policy specified

Blazor Routable Components

Severity	Rule	Description
High	Unauthenticated routable component	Component with [Route] but without [Authorize]
Low	Authorize without role/policy	[Authorize] present but no Roles or Policy specified

Azure Functions

Severity	Rule	Description
High	Unauthenticated Azure Function	AuthorizationLevel.Anonymous and no [Authorize] attribute
Low	Authorize without role/policy	[Authorize] present but no Roles or Policy specified

OData Endpoints

Severity	Rule	Description
High	Unauthenticated state-changing endpoint	DELETE, POST, PUT, or PATCH without [Authorize]
Medium	Missing authorization declaration	Endpoint has neither [Authorize] nor [AllowAnonymous]
Low	Authorize without role/policy	[Authorize] present but no Roles or Policy specified

License

See LICENSE.