Custom Field on Webstore: Spambots and Huge Cart Abandonment

At the end of last week, I noticed some very unusual jumps in cart abandonment numbers.
Also, several customers contacted us over the weekend with reports that our webstore was not working properly: problems with large delays in between clicking "buy" or "checkout" and the time it took for NS checkout to finally display.

After contacting support, who found that a custom field (custom transaction item option - text area) that is required to purchase an item (the field requires buyers to enter in a name that will be included on the sales order form per item) was being repeatedly hit by a spambot and that the security of the field had been compromised and was creating and abandoing shopping carts over and over.