Two-factor authentication isn’t always enough as fraudsters have found vulnerabilities in some of these system, according to a report from Gartner Inc.
Trojan-based, man-in-the-browser attacks have evaded strong two-factor authentication, enabled through one-time password tokens. Other strong authentication factors, such as those using chip cards and biometric technology that rely on browser communications, can also be defeated.
Some examples of attacks that have worked include:
Malware that overwrites transactions sent by a user to the online banking Web site. This happens behind the scenes, so that the user does not see the revised transaction values. Many online banks will then communicate back to the user’s browser the transaction details that need to be confirmed by the user with a token, but the malware will change the values seen by the user to what was originally entered. This way, neither the user nor the bank realizes that the data sent to the bank has been altered.
Authentication that depends on out-of-band authentication using voice telephony is circumvented by a simple technique whereby the fraudster asks the phone carrier to forward the legitimate user’s phone calls to the fraudster’s phone.
Avivah Litan, vice president and analyst at Gartner, recommended that more than one measure be used to achieve fraud prevention results and outlined some proven measures that can prevent attacks from succeeding:
Fraud detection that monitors user access behavior. This method captures and analyzes all of the user’s Web traffic, including login, navigation and transactions, and can spot abnormal access patterns that indicate that an automated program is accessing the application, rather than a human being.
Fraud detection that monitors suspect transaction values. This function looks at a particular transaction and compares it to a profile of what constitutes “normal” behavior for that user.
Out-of-band user transaction verification. This type of verification does not use the same primary communication channel–for example, the user’s browser–and uses a different communication channel to verify a transaction request.
“Fraudsters have definitely proven that strong two-factor authentication processes can be defeated” says Litan. “Enterprises need to protect their users and accounts using a three-prong layered fraud prevention approach that uses stronger authentication, fraud detection and out-of-band transaction verification and signing for high risk transaction.”