For an extra level of security, you can add a CAPTCHA to the Admin Login page.
Administrator users can reload the displayed CAPTCHA by clicking the Reload icon in the
upper-right corner of the image. The number of reloads is not limited.
To configure CAPTCHA for the Admin:
1. On the Admin menu, select System > Configuration. Then in the panel on the left under
Advanced, select Admin.
2. In the upper-right corner, set Current Configuration Scope to “Default.”
3. Click to expand the CAPTCHA section, and complete the settings as described below.
4. When complete, click the Save Config button.