Advanced malware used for gaining access credentials


Malware has been one of the main techniques used to access user login credentials, giving fraudsters absolute power over online communication between customers and their banks. Fraudsters have developed effective methods to evade anti-virus software, the most common security control used by online banking customers. Such malware often uses Man-in-the-Browser (MitB) attacks in which the malware injects its code into the browser, controls the information exchange between the bank and the customer, and tampers with content displayed in the browser. MitB became the weapon of choice for financial fraudsters as it allowed them to tamper with web traffic and collect information – beyond usernames and passwords. It allowed them to change login pages and ask for additional details that allow them to answer out-of- wallet secondary authentication questions.


MitB malware has been targeting online payment platforms since day one. While popular payment services such as PayPal are constantly being targeted by most malware, smaller payment systems are now appearing on cyber criminals’ radar. A security team at Trusteer, the leading provider of endpoint cybercrime prevention solutions, recently analysed a new Citadel malware variant that targeted, among others, Payza – a payment platform popular in developing countries that have limited access to online financial services.


As you can see, the Citadel malware adds the “Pin” field to the Payza login page. This pin is used every time a user wants to send, add or withdraw funds. By obtaining the victim’s email, password and pin, cyber criminals can take over the account and commit fraudulent transactions. MitB malware continues to pose a serious threat to online financial services, and users must stay vigilant and be on the lookout for new and suspicious requests, even when accessing trusted sites like their bank or online payment website.


Bypassing strong two-factor authentication


In traditional phishing attacks, the victim reaches a phishing website and submits login credentials which are stored for later use by e-criminals. The introduction of strong two- factor authentication, especially one time passwords (OTPs), rendered these types of phishing attacks useless as fraudsters could not use static stolen credentials to commit fraud. With strong two-factor authentication the user is required to provide an OTP, which is limited in time, as part of the login process. There are many OTP approaches; some of them are based on token devices that users carry along with them, others are sent to the user's phone as an SMS text or voice call. Even if the fraudsters managed to capture OTP data there is only a short period of time in which this data can be used.


But phishing attacks have become more sophisticated and we have recently seen advanced attacks in which fraudsters have been able to capture and use the OTP in real time, rendering two-factor authentication ineffective against this type of attack.


The Citadel variant includes Payza-specific MitB code to alter the fields the user is asked to fill in when accessing the login page.


The legitimate Payza login screen


Many organisations that used strong two- factor authentication were dismissive of phishing attacks as they assumed that they were incapable of bypassing their security controls. This is no longer the case. Using phishing kits with real-time capabilities, fraudsters have improved their operations to conduct fraud instantly.


A sharp increase in usage of mobile devices


If a user accesses his/her Payza account from an infected computer, Citadel will alter the login screen to look like this:


© CI TY S ECURI TY MAGAZ INE – SUMMER 2013


Why do criminals find the mobile channel so attractive? Let’s take a step back and examine things from the fraudster’s point of view. Popular online fraud schemes typically involve stolen credentials (using malware and phishing) which are used to perform an account takeover. They also require the fraudster to pass authentication procedures, which can be quite challenging. One of the most basic authentication methods is device ID. A criminal logging in to an online banking service using a new device, which is unknown to the bank, may trigger a fraud alert. This allows the bank to potentially block the attack by flagging the account access as suspicious. But what if the fraudster used a device that is both anonymous and unsuspicious to the targeted bank?


Mobile devices, and iPhones specifically, have an interesting trait – they all look the same. Not just physically, but also their device fingerprint. When a user browses a web site from his mobile browser (let’s take an iPhone and a Safari browser as our example), the device characteristics are identical to almost all other iPhones: same hardware, same browser, same fonts, etc. This scenario is a criminal’s dream come true.


Trusteer recently discovered several fraud schemes targeting a large European bank. Among the interesting findings across factors such as device usage, fraud behaviour profiling and account access anomalies, one fact clearly stood out: there is a sharp increase in the use of mobile devices to conduct account takeover fraud. Even more interesting, the bank experienced fraud that originated from their mobile channel.


In this attack scheme, criminals use phishing and malware to steal credentials from the victim’s PC. They then login to the bank using a mobile device and a native mobile browser (no mobile banking app is used). The bank cannot uniquely identify the device because the criminal’s iPhone looks exactly like the victim’s iPhone (or like any other iPhone for that matter). The criminal’s login attempt will not trigger any risk indicators and a fraudulent transaction is just a matter of time.


Conclusion


Online financial fraud is on the rise. In the last few years fraudsters have developed sophisticated techniques using phishing schemes, advanced malware and the mobile channels to gain access to user accounts and steal financial assets. Users should be aware of these risks and avoid suspicious links as they may lead them to a phishing site or malicious sites where they can get infected with fraud- enabling malware.


But this is not enough. Online banking and financial services providers need to identify and block fraudulent activity. It is important for institutions to reduce the time it takes to detect they are being targeted by a fraud attack. And targeted online services should not allow users to access their websites using computers that are infected with malware. Successful fraud prevention is an ongoing battle that requires accurate and timely intelligence, highly skilled teams that work around the clock, continuous innovation and creativity to always stay one step ahead of the fraudsters.


Dana Tamir Director of Enterprise Security at Trusteer www.trusteer.com


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