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Deploy PlantUML safely

Our collaboration with Sysdream leads us to introduce the notion of security profile within PlantUML.

Starting with version 1.2020.11, you have to choose which security profile use when running PlantUML. The default one is LEGACY. It emulates the behavior of older PlantUML versions. This means you can safely upgrade to 1.2020.11. However, you should then pick up an appropriate mode for your usage.

This is needed because PlantUML can be used in many different configurations which require different security setting.

If you are using a version older than 1.2020.11 and if your system is accessible from Internet, you should probably upgrade because older versions of PlantUML may expose a little more than you would expect. Even the LEGACY default mode is more secure than older PlantUML behaviour.

Choose your Security Profile

The Security Profile can be set two different ways:

In practice, you can do:

set PLANTUML_SECURITY_PROFILE=INTERNET

or

setenv PLANTUML_SECURITY_PROFILE INTERNET

Another way is an option in the command line (do not forget the -D flag):

java -DPLANTUML_SECURITY_PROFILE=INTERNET -jar /path/to/plantuml.jar ...

Or if you are using Java and PlantUML as a library:

System.setProperty("PLANTUML_SECURITY_PROFILE", "INTERNET");

List of Security Profiles

There are five different profiles you can choose from :

UNSECURE

When PlantUML runs in UNSECURE mode, it means that PlantUML can access to all local files of the running server and can access to any URL.

Despite its name, this does not mean that you should not use it. If you are running locally PlantUML from some scripts for your generated documentation, this is completely safe and ok.

It may become an issue if this is used from a Web Server which is accessible from Internet, because you cannot control what users are doing in their diagram text.

LEGACY

Right now, this mode is the default mode for PlantUML. It gives the same result as older PlantUML versions: full access to local files and full access to URL. This means that you can safely upgrade to version 1.2020.11 without breaking your scripts.

However, after upgrading, you should consider setting an appropriate Security Profile other than LEGACY because this mode will be removed in future releases and the default mode will be more restricted.

INTERNET

This mode has been designed for server which are connected to Internet.

When running in INTERNET mode, PlantUML cannot have access to any local files (except if you are using allowlists, see below). However, all URLs on port 80 or 443 are accessible. If you need some specific port (like 8080 for some Intranet server), you can also use allowlists.

ALLOWLIST

In ALLOWLIST mode, PlantUML cannot have any access to local files or URL. You have to use allowlists to explicitely authorize access to local or remote ressources.

SANDBOX

In SANDBOX mode, PlantUML cannot have any access to local files or URL. Even allowlists lists are ignored. So this mode is completely close.

The main interest of this one is testing: if someone succeed some access running this mode, it means we have a security hole and we will fix it.

Allowlists

There are three different variables to define allowlists:

These variables can be set using the same way as PLANTUML_SECURITY_PROFILE.

plantuml.allowlist.path

This variable lists using ; (Windows) or : (Linux) separator the folders users will be authorized to have access to.

java -DPLANTUML_SECURITY_PROFILE=INTERNET  -Dplantuml.allowlist.path=/usr/common/:/usr/plantuml/  ...

plantuml.include.path

This is very close to plantuml.allowlist.path. The only difference is that users will not have to specify full path of files for those folders: PlantUML will search files in thoses folder, even if users give only filenames without full path.

java -DPLANTUML_SECURITY_PROFILE=INTERNET  -Dplantuml.include.path=c:/windows/plantuml/  ...

plantuml.allowlist.url

This variable lists using ; (for both Windows and Linux) separator the URLs users will be authorized to have access to.

java -DPLANTUML_SECURITY_PROFILE=ALLOWLIST  -Dplantuml.allowlist.url=https://plantuml.com/;http://somelocalserver:8080/commons/  ...