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Online banking TrojansRecent developments and countermeasuresDND, ISF, ISACA member meeting 02. May 2011André N.KlingsheimIT security specialist, PhD

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Outline• Skandiabanken’s login procedures• ”Traditional” Trojans• Recent developments• Recent security adjustments 2

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The login procedures• Online banking password – With One Time Password (OTP) by SMS – Or from a code card• BankID – BankID password – OTP from code card• BankID mobile – Pin entered on mobile phone 3

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Login procedures figure 4

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Traditional Trojans• Most simplistic Trojans – Are essentially keyloggers – Record your usernames and passwords – Sends the data to some drop site on the Internet – Attacker later picks up the data from drop site – Will compromise traditional username/password schemes (single factor authentication)• High security sites have introduced OTPs to counter this threat (others follow) 5

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More recent Trojans• Not so simplistic Trojans – Target two-factor authentication – Target systems employing reauthentication • Means you need to supply new OTPs to perform sensitive operations – Attempt to steal OTPs – Have functionality to show malicious webpages to the user, to confuse the user into giving several OTPs – Requires user interaction 6

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More recent Trojans II• More advanced Trojans – Target two-factor authentication – Performs attack in realtime • Overcomes short lived OTPs • Overcomes singular OTPs – Requires user interaction 7

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Modern Trojan threat• Advanced Trojans can conceal rogue payments: – Rewrite payment registry – Rewrite account statement• Can make the attack undetectable for the user – There are no visual indications that something is wrong, i.e. the account statement looks ok• We’ll have a look at the Zeus Trojan – Screenshots stolen from Symantec video (9 mins worth watching!) – www.youtube.com/watch?v=CzdBCDPETxk 8

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Zeus example (original page) 9

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Zeus example (modified page) 10

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Zeus config 11

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It gets worse... 12

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Combined PC/mobile Trojan threat• Trojans on pc attempt to install mobile Trojan – Ask customer to install ”App” during login – Steal username/password on pc, OTP on mobile• Some attacks reported in Europe – This is an upcoming threat• We haven’t seen any of these attacks in Norway yet 13

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Zeus combined mobile Trojan •www.securityweek.com/zeus-goes-mobile-targets-online-banking-two-factor-authentication 14

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Combined PC/mobile Trojan threat II• Mobile platforms are consolidated – iOS (iPhone), Android, Windows Mobile 7 – Makes mobile Trojans scale better – Increases ROI for attackers, increases our risk• Installing the mobile Trojan still requires user participation – User must supply phone model and maker – User must accept installation on the phone 15

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Countermeasures 16

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Our security design• Payment authorization – By an OTP (reauthentication) – Or by signature, BankID/BankID• Required for: – Payments to new recipients – Payments over a certain threshold• Hampered attacks from traditional Trojans• Balanced usability/security 17

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The OTPs• Generated securely – Infeasible to guess them• Short lived, 15 mins• You can only have one valid OTP at any given moment – Requesting a new OTP invalidates the previous – Forces real time attack• OTP is tied to the operation you perform – Login/payment/changing personal information etc 18

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Stopping the attack at the client 19

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Recent security adjustments• We’ve done some important security design changes to our online bank to deal with the modern threats• Most noteworthy (and visible to our customers) – Introduced contextual information with our OTPs• The effect: – Faced with a Trojan attack, all attempted rogue transactions are detectable for the customer 20

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OTP via SMS, with context 21

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Avoiding the attack?Look for mismatch betweenaccount/amount in onlinebank and mobile phone 22

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The standard countermeasures• These are the usual suspects – Surveillance of Trojan activity (through partner) – IDS/firewall/etc – Payment monitoring – This is not an exhaustive list • In addition – Tight collaboration with other Norwegian banks – Information sharing (extremely important) – Security collaboration, not competition 23

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Thank you!• You’ll find me online: – andre.klingsheim (at) skandiabanken (dot) no – Blog: www.dotnetnoob.com – Twitter: @klingsen• I don’t want to be your Facebook friend• Note: Skandiabanken participates with two lightning talks at the upcoming Roots conference 24