How to add Captcha In Your Login Page in Oracle Apex

Step 1

Create a item in your login page.

Step 2

Copy below code into item "Post Text"

<div style="background-color:#FFF; border:1px solid #ececec; padding:3px;">
<img width="25" height="25",=""
src="APEX_050100.wwv_flow_image_generator.get_image?p_position=1&p_sessionid=&APP_SESSION."><img
width="25" height="25",=""
src="APEX_050100.wwv_flow_image_generator.get_image?p_position=2&p_sessionid=&APP_SESSION."><img
width="25" height="25",=""
src="APEX_050100.wwv_flow_image_generator.get_image?p_position=3&p_sessionid=&APP_SESSION."><img
width="25" height="25",=""
src="APEX_050100.wwv_flow_image_generator.get_image?p_position=4&p_sessionid=&APP_SESSION."><img
width="25" height="25",=""
src="APEX_050100.wwv_flow_image_generator.get_image?p_position=5&p_sessionid=&APP_SESSION.">
</div>

Step 3 

Create a process and copy the code into your process and select when process execute button.

DECLARE
   vCount   NUMBER := 0;
BEGIN
      IF TRIM (:P101_CAPTCHA) IS NULL
      THEN
         RAISE_APPLICATION_ERROR (-20001,
                                  'Please Confirm Verification Code.');
      END IF;

      BEGIN
         SELECT 1
           INTO vCount
           FROM APEX_050100.wwv_flow_request_verifications
          WHERE SESSION_ID = :APP_SESSION
                AND SUBSTR (VERIFICATION_STRING, 1, 5) = :P101_CAPTCHA;
      EXCEPTION
         WHEN OTHERS
         THEN
            RAISE_APPLICATION_ERROR (-20001,
                                     'Please Confirm Verification Code.');
      END;

      IF vCount = 1
      THEN
         NULL;
      ELSE
         RAISE_APPLICATION_ERROR (-20001,
                                  'Please Confirm Verification Code.');
      END IF;
END;

Step 4

Error Message

#SQLERRM_TEXT#