# How do I install untrusted packages safely? Is it safe to run Composer as superuser or root?

Certain Composer commands, including `exec`, `install`, and `update` allow third party code to
execute on your system. This is from its "plugins" and "scripts" features. Plugins and scripts have
full access to the user account which runs Composer. For this reason, it is strongly advised to
**avoid running Composer as super-user/root**. All commands also dispatch events which can be
caught by plugins so unless explicitly disabled installed plugins will be loaded/executed by **every**
Composer command.

You can disable plugins and scripts during package installation or updates with the following
syntax so only Composer's code, and no third party code, will execute:

```shell
php composer.phar install --no-plugins --no-scripts ...
php composer.phar update --no-plugins --no-scripts ...
```

Depending on the operating system we have seen cases where it is possible to trigger execution
of files in the repository using specially crafted `composer.json`. So in general if you do want
to install untrusted dependencies you should sandbox them completely in a container or equivalent.

Also note that the `exec` command will always run third party code as the user which runs `composer`.

See [Environment variable - COMPOSER_ALLOW_SUPERUSER](../03-cli.md#composer-allow-superuser)
for more info on how to disable warning