Reducing spam in Moodle

Background

What exactly is the problem? Read why porn spam has been appearing in Moodle sites.

The best thing to do

Upgrade to 1.9.4 or later and use the new Security report to analyse your configuration. Then do all the things it tells you.

Critical settings

1. Make sure that 'register_globals' is switched off in your PHP settings (this is the default). Otherwise your site may be at risk of being cracked, allowing spammers to modify your scripts and insert spam wherever they like.
2. Keep "Force users to login for profiles" enabled in Administration > Security > Site policies to prevent anonymous visitors and search engines from seeing user profiles.
3. Keep "Profiles for enrolled users only" enabled in Administration > Security > Site policies (in Moodle 1.6.9, 1.7.7, 1.8.8 and in 1.9.4 onwards).

Strong recommendations

• Make sure you upgrade your site often. Recent versions of Moodle have new fixes and warnings that will help you avoid security issues.
• Consider the spam risks involved in allowing certain capabilities for visitor accounts, such as replying to forum posts or posting to blogs.

Allowing self-registration

If you don't need it, please keep self-registration disabled (it's the default) in Administration > Users > Authentication > Manage authentication common settings.

If you must use Email-based self-registration to allow people to make their own accounts then:

1. Add spam protection to the new account form by enabling reCAPTCHA (in Moodle 1.9.1 onwards) - see Security FAQ for details of how to do so. ReCAPTCHA is quite effective against most automated spambots, but will not foil human spammers at all.
2. Limit self registration to particular email domains with the allowed email domains setting or deny email addresses from particular domains, such as mailinator.com and temporaryinbox.com, with the denied email domains setting. Both settings are in Administration > Users > Authentication > Manage authentication common settings.
3. Consider only enabling self registration for a short period of time to allow users to create accounts, and then later disable it.
4. Keep "Email change confirmation" enabled in Administration > Security > Site policies (in Moodle 1.8.6 and in 1.9.2 onwards).

Cleaning up spam

If your site was open in the past and you have a spam problem then here are some things you can do to clean up the profiles:

1. Use our Spam Cleaner - a simple script to help you delete spammer accounts more easily (in future versions of Moodle this will be a standard Admin report):
   • Download: spamcleaner.php
   • Feedback/discussion: issue MDL-17144 in the Moodle tracker
2. Browse your user list looking for patterns to detect users who need to be deleted. For example, spammers might have chosen a country that none of your real users has.
3. Use the "Bulk user actions" tool under Admin > Users > Accounts to find all these users and delete them. Note that versions prior to 1.6.7, 1.7.5, 1.8.6, 1.9.2 had a bug that did not properly hide deleted user profiles, so make sure you have upgraded to a later version if you want to keep user profiles visible to the world.