3-D Secure is an XML-based protocol used as an added layer of security for online credit and debit card transactions. The 3-D Secure protocol was developed by Visa to improve the security of Internet payments and offered to customers as the Verified by Visa service. Services based on the protocol have also been adopted by MasterCard, under the name MasterCard SecureCode, and by JCB International as J/Secure.
3-D Secure allows better authentication of the payment card holder by their card issuer when they are making purchases online from a merchant's web site. The rollout of 3-D Secure to merchants is being encouraged by the card schemes offering better cover against fraud losses to the merchants. A merchant without 3-D Secure is liable for transactions that subsequently turn out to be fraudulent even if a valid transaction authorisation was received at the time.
3-D Secure should not be confused with a Card Security Code which is a short numeric code that is printed on the card.
Description and basic aspects of the protocol
The basic concept of the protocol is to tie the financial authorization process with an online authentication. This authentication is based on a three domain model (that is the 3-D in the name). The three domains are: Acquirer Domain (the commerce), the Issuer Domain (the bank issuer of the credit card) and finally the Interoperability Domain (Worldwide credit card and support).
The protocol uses XML messages sent over SSL connections with client authentication (this ensures the authenticity of both peers, the server and the client, using digital certificates).
A transaction using Verified by Visa/SecureCode will initiate a redirect to the website of the card issuing bank to authorize the transaction. Each issuer could use any kind of authentication method (the protocol does not cover this) but typically, a password-based method is used, so to effectively buy on the Internet means using a secret password tied to the card. The Verified by Visa protocol recommends the bank's verification page to load in an inline frame session. In this way, the bank's systems can be held responsible for most security breaches.
The main difference between Visa and MasterCard implementations resides in the method to generate the AAV (Accountholder Authentication Value): MasterCard uses UCAF (Universal Cardholder Authentication Field) and Visa uses CAVV (Cardholder Authentication Verification Value).
Implementing the protocol
The specifications are currently at version 1.0.2. Previous versions 0.7 (only used by Visa USA) and 1.0.1 have become redundant and are no longer supported. MasterCard and JCB have adopted version 1.0.2 of the protocol only.
In order for a Visa or MasterCard member Bank to use the service, it has to operate compliant software that supports the latest protocol specifications. Once compliant software is installed, the member bank will perform Product Integration Testing with the Payment System Server before it rolls out the system.
The "Verified by Visa" system has drawn some criticism,   since it is hard for users to differentiate between the legitimate Verified by Visa pop-up window or inline frame, and a fraudulent phishing site. This is because the pop-up window is served from a domain which is:
- Not the site where the user is shopping.
- Not the card issuing bank
- Not visa.com
Indeed, the Verified by Visa system has been mistaken by users for a phishing scam and has itself become the target of some phishing scams. The newer recommendation to use an inline frame (IFrame) instead of a popup has reduced user confusion, but at the cost of making it harder for the user to verify that the page is genuine in the first place—as of 2008, most web browsers do not provide a simple way to check the security certificate for the contents of an iframe.
Some card issuers also use Activation During Shopping (ADS), in which cardholders who are not registered with the scheme are offered the opportunity of signing up (or forced into signing up) during the purchase process. This will typically take them to a form in which they are expected to confirm their identity by answering security questions which should be known to their card issuer. Again, this is done within the iframe where they cannot easily verify the site they are providing this information to—a cracked site or illegitimate merchant could in this way gather all the details they need to pose as the customer.
Cardholders who are not willing to take the risk of registering their card during a purchase, with the commerce site controlling the browser to some extent, can instead go to their bank's home page on the web in a separate browser window and register from there. When they go back to the commerce site and start over they should see that their card is registered. The presence on the password page of the Personal Assurance Message (PAM) that they chose when registering is their confirmation that the page is coming from the bank. This still leaves some possibility of a man-in-the-middle attack if the card holder cannot verify the SSL Server Certificate for the password page. Some commerce sites will devote the full browser page to the authentication rather than using a frame (not necessarily an iFrame, which is a less secure object anyway). In this case the lock icon in the browser should show the identity of either the bank or the operator of the verification site. The cardholder can confirm that this is in the same domain that they visited when registering their card, if it is not the domain of their bank.
When signing up for "Verified by Visa" in the USA the user is required to enter last 4 digits of their social security number. If the digits are incorrect, the user gets to try a different combination and the number of attempts is unlimited. This makes it theoretically possible to "guess" someone's last four social security digits, simply by trying all numbers from 0001 to 9999. Most if not all sites will lock an account out of registration, without blocking offline use of the card, after a small number of errors.
The password required is limited to twenty characters, preventing the use of longer passphrases.
- antiworm: Verified by Visa (Veriphied Phishing?)
- Industry lays into 3-D Secure - 11 Apr 2008 - IT Week
- Verified by Visa scheme confuses thousands of internet shoppers | Money | The Guardian
- Is securesuite.co.uk a phishing scam?
- Verified By Visa Activation - Visa Phishing Scams - MillerSmiles.co.uk
- http://www.visaeurope.com/documents/vbv/verifiedbyvisa_activationduringshopping.pdf Activation During Shopping