moodle-local_csp

• Why would you want this?
• What is this?
• How does it work?
• Branches
• Performance impact
• Installation
• References

Why would you want this?

Security, security, security.

This plugin helps you to detect and mitigate certain classes of security errors in your Moodle such as:

• Mixed content (https/http) after you switched to HTTPS.
• Same origin (or specified origin) policy for scripts and media data.
• Unintended iframes

What is this?

This plugin allows you to easily test and rollout Custom Security Policy headers across your moodle.

Examples:

• Report/enforce SSL origin for links, images etc.
• Report/enforce same-origin for links, images etc.

How does it work?

Site admin configures CSP headers: Content-Security-Policy or Content-Security-Policy-Report-Only in the plugin settings. Header Content-Security-Policy-Report-Only is for recording CSP violations in Moodle and reviewing them later from the plugin's report page.

Enabling of Content-Security-Policy blocks browser from showing site resources that violate defined rules.

CSP support in browsers is quite good:

https://caniuse.com/#search=CSP

To get started visit this admin settings page and enter a basic policy into csp_header_reporting and enable it with csp_header_enable.

/admin/settings.php?section=local_csp_settings

Then you will need to wait for a couple days or a week to collect statistics on what pages are violating that policy. You can see all the violations here:

/local/csp/csp_report.php

As you discover violations you need to make the business decision of which domains should be allowed and either amend the CSP policy, or change the learning content so they do not violate the policy.

Each time you change the policy you can reset the statistics, either partially for each directives or fully. When you gain confidence in your policy you can convert it from a 'reporting only' policy to a real policy that is enforced.

Be aware that if you prematurely set a policy which is too strict you can break your learning content and even completely break Moodle itself.

Branches

Moodle verion	Branch	PHP
Moodle 4.1+	MOODLE_401_STABLE	7.4
Moodle 3.3 to 4.0	master	7.2
Moodle 2.7	MOODLE_27_STABLE	5.5

Performance impact

While this plugin is relatively lightweight, if you have a reporting policy in place which has a large number of violations then each of those violations will be reported to the collector endpoint which adds load to your server.

It is recommended to try and fix policy issues as they are identified in the summary reports, or white list the content so it is no longer reported on.

Installation

Checkout or download the plugin source code into folder local\csp of your Moodle installation.

git clone git@github.com:catalyst/moodle-local_csp.git local\csp

or

wget https://github.com/catalyst/moodle-local_csp/archive/master.zip
mkdir -p local/csp
unzip master.zip -d local/csp

Then go to your Moodle admin interface and complete installation and configuration. Example policy 'default-src https:;' will be reporting or enforcing the links to be HTTPS-only. Please note, the whole moodle website should be accessible via HTTPS for this to work.

For more examples of other CSP directives please read here.

References

See also:

Convert http embedded content to https on https sites where available https://tracker.moodle.org/browse/MDL-46269

A complementary plugin which works by searching the moodle DB for bad links: https://github.com/moodlerooms/moodle-tool_httpsreplace

This plugin was developed by Catalyst IT Australia: https://www.catalyst-au.net/