Black List Plugin

Utility to keep malicious users away from a public TWiki site

Description

This is a simple utility to keep black sheep away from a public TWiki site. The site can be protected against excessive page access (e.g. by bad robots), suspicious activities of users, such as multiple registrations or rapid topic updates indicating Wiki:WikiSpam, or saving text with wiki-spam.

The Plugin monitors activities by IP address and uses three IP address lists to protect the TWiki site:

• WHITELIST: Manually maintained list of users who should never get on the BANLIST
• BLACKLIST: Manually maintained list of malicious users
• BANLIST: Automatically updated list of users with suspicious activities

On topic save, text is compared to a known list of spam patterns. If wiki-spam is identified, topic save is cancelled, an error message is shown, and the IP address is put on the BANLIST. Two wiki-spam lists are used:

• Local SPAMLIST: Manually maintained list of spam patterns
• Public wiki-spam list: Big list of wiki-spam patterns, retrieved from external web site

Users on the BLACKLIST and BANLIST will have every page access delayed by one minute and will get an error message.

The registration form can also be protected from improper use.

To fight Wiki-spam, the Plugin can also add a rel="nofollow" parameter to external URLs. Search engines will not follow links that have this parameter, taking away the incentive to add spam to TWiki.

Plugin Settings

Plugin settings are stored as preferences variables. To reference a plugin setting write %<plugin>_<setting>%, i.e. %INTERWIKIPLUGIN_SHORTDESCRIPTION%

General settings

• One line description, is shown in the TextFormattingRules topic:
  • Set SHORTDESCRIPTION = Utility to keep malicious users away from a public TWiki site

• Debug plugin: (See output in data/debug.txt)
  • Set DEBUG = 0

• Log access of blacklist and spam list activities: (0 or 1)
  • Set LOGACCESS = 1

• Access restriction:
  • Set ALLOWTOPICCHANGE = TWikiAdminGroup
  • Set ALLOWTOPICRENAME = TWikiAdminGroup

WHITELIST, BLACKLIST and BANLIST settings

• WHITELIST: Comma delimited list of IP addresses; possible to use partial addresses ending in a dot
  • Set WHITELIST = 127.0.0.1

• BLACKLIST: Comma delimited list of IP addresses; possible to use partial addresses ending in a dot
  • Set BLACKLIST = 203.88.152., 203.88.155., 219.65.75.

• BANLIST configuration, comma delimited list of:
  1. Points for registration
  2. Points for each save and upload
  3. Points for view and other actions
  4. Points for view raw
  5. Threshold to add to BANLIST
  6. Measured over time (in seconds)
  • Set BANLISTCONFIG = 10, 5, 1, 5, 120, 300
  • Your current score: %BLACKLISTPLUGIN{ action="user_score" }% for IP address 18.116.13.192

• Message for users on BLACKLIST and BANLIST:
  • Set BLACKLISTMESSAGE = Your IP address 18.116.13.192 is black listed at the TWiki web site due to excessive access or suspicious activities. Please contact site administrator twiki@ufba.br if you got on the list by mistake.

Wiki-spam filtering settings

• Filter wiki-spam on topic save and HTML file uploads based on SPAMLIST: (0 or 1)
  • Set FILTERWIKISPAM = 1

• Comma separated list of Web.Topics to exclude from wiki-spam filtering on topic save:
  • Set SPAMEXCLUDETOPICS =

• Public wiki-spam list: Big list of wiki-spam patterns, retrieved from external web site (thanks to MoinMoin's AntiSpamGlobalSolution wiki-spam list)
  • Set SPAMLISTURL = http://arch.thinkmo.de/cgi-bin/spam-merge

• Cache refresh time (in minutes) for public wiki-merge pattern list:
  • Set SPAMLISTREFRESH = 60

• Cache refresh time (in minutes) for internal wiki-spam regular expression cache:
  • Set SPAMREGEXREFRESH = 10

• Message for users trying to save text with wiki-spam:
  • Set WIKISPAMMESSAGE = Wiki-spam detected: "%WIKISPAMWORD%" is a banned word and cannot be saved. Your IP address 18.116.13.192 is black listed at the TWiki web site due to suspicious activities. Please contact site administrator twiki@ufba.br if you got on the list by mistake.

Registration protection settings

• Protect registration: (number of minutes to expire, 15 minutes is recommended, 0 to disable)
  • Set REGEXPIRE = 0
  • If enabled, a magic number is protecting the registration process. TWiki expects a form field with a magic number. An error message is shown if not valid or if expired. This makes it harder to register a user by a script. A hidden field needs to be added to the registration form:
    <input type="hidden" name="rx" value="%BLACKLISTPLUGIN{ action="magic" }%" />

• Message shown when using registration form incorrectly: (this message is deliberately vague)
  • Set REGMESSAGE = Registration failed, please try again.

Nofollow link setting

• Add a rel="nofollow" parameter to external URLs. Use this is to fight Wiki-spam. Search engines will not follow the link if a URL has a nofollow parameter, such as <a href="http://spammer.com/" rel="nofollow">. Specify topic age in hours for which the nofollow parameter should appear (set it to a value that gives you enough time to remove spam); set it to -1 to add the nofollow parameter unconditionally to external URLs; or 0 to disable: (-1, 0, 1...N)
  • Set NOFOLLOWAGE = -1

Plugin Installation Instructions

Note: You do not need to install anything on the browser to use this plugin. The following instructions are for the administrator who installs the plugin on the server where TWiki is running.

• Download the ZIP file from the Plugin web (see below)
• Unzip BlackListPlugin.zip in your twiki installation directory. Content:

  File:	Description:
  data/TWiki/BlackListPlugin.txt	Plugin topic
  data/TWiki/BlackListPlugin.txt,v	Plugin topic repository
  lib/TWiki/Plugins/BlackListPlugin.pm	Plugin Perl module
  pub/TWiki/BlackListPlugin/.htaccess	Apache access control to protect pub dir
  templates/oopsblacklist.tmpl	Generic oops message

• Make sure pub/TWiki/BlackListPlugin/ is writable by the CGI user (typically nobody)
• Run the configure utility in your browser to enable the Plugin
• Make sure that non-administrators cannot edit this plugin topic. By default, this topic is write protected with an ALLOWTOPICCHANGE = TWikiAdminGroup setting.
• Test if the installation was successful:
  1. Using above form, add the IP address of one of your workstations to the BANLIST
  2. Access TWiki from that workstation
     • if you look at a TWiki topic (with the view script) you should see the BLACKLISTMESSAGE (defined above) after a one minute timeout
     • else, you should get an 500 Internal Server Error for other scripts
  3. On a different workstation, remove the IP address of the test workstation from the BANLIST

Known Issues and Limitations

• With TWiki 4.0.2 on some platforms, notably Solaris, attached files are uploaded with a zero file size. This is because there is a bug in how TWiki 4.0.2 handles the beforeAttachmentSaveHandler. If affected, upgrade TWiki or apply bug fix Item2390
• Scan for script eval() and escape() is currently hardcoded

Plugin Info

Related Topics: TWikiPreferences, TWikiPlugins, TWiki:Codev.WikiSpam