Defending Aganist Spambots - Honeypots

Honeypots are a concept taken straight from email spam prevention and come in 2 types: honey pot fields and honey pot forms. Honeypots are basically a very tempting submission location that should never receive real data. Any submissions to the honeypot are automatically labeled as spam.

Honey pot fields are fields within a form that should always be left blank and are indicated as such to the user via a label. When a form is submitted with that field completed, it can be quickly marked as spam, discarded and the submitter fingerprint recorded for tracking. In order to make the field tempting, the field name and field type should be chosen wisely. An input field with a name of “website” and a type of “url” is more tempting to a spambot than an input field with a name of “honeypot” and a type of “text”. Good spambots will detect the field type and name and try to inject appropriate content to bypass automated validation mechanisms.

Example Honey pot field

<style> form>div#form_hp { position: absolute; left:-99999px; z-index:-99999; } </style> <form method="POST" action=""> <div id="form_hp"> <label for="another_email">Leave this field blank</label> <input id="another_email" name="another_email" type="email" value=""/> </div> <!--- the real form content--> </form>

When hiding the honey pot field, the best method is to use embedded CSS to shift the field wrapper off the screen. A good quality bot will check to see which fields are natively displayed and only submit information to those displayed. Fields with “display:none” or “visibility:hidden” can be easily marked as hidden. Even situations where the field itself is absolutely positioned off screen can be detected without too much difficulty. Moving the wrapper off screen via CSS requires considerably more programming to detect, as all the CSS needs to be parsed and applied prior to evaluating the display nature of any field. The CSS should be embedded into the HTML to prevent loading issues, where an external CSS file is not loaded, and the wrapper, with the honey pot fields are displayed to the user.

Honey pot forms are entire forms that a real user should never find or submit information to, though are easily detected via automated scripts. Hidden links to the page containing the form are embedded in the footer or header and indicated that they should not be followed by bots. The page then contains a description that clearly states the form should not be used and a bunch of tempting fields to submit. Any submissions by this form are consequently deemed a bot and appropriate measures are taken. This type of honey pot can be integrated into a web-server layer filter (via a web application firewall like modsecurity) where the submissions are track prior to the application layer and attacks are mitigated at the web server.

The biggest concern with honey pot forms are search engines, and their bots finding the pages, and then displaying the page as a result in search results. Appropriate steps should be taken to minimize bots taking the honeypot links via usage of the rel=”nofollow” attribute in the hidden links, the ‘’ tag in the html head section of the form page and clear text on the page saying not to submit this form.