September 4, 2012 By Amit Klein 2 min read

IBM has discovered a new Tatanga attack against chipTAN systems used by banks in Germany, which generates unique transaction authentication numbers (TAN). These systems require that the bank card for the account be inserted in the device to generate a TAN that is specific to the current transaction.

How the Attack Bypasses chipTAN Systems

Tatanga checks the user account details, including the number of accounts, supported currencies and balance/limit details. It then chooses the account from which it could steal the highest amount. Next, it initiates a transfer. At this point, Tatanga uses a webinject to trick the user into believing that the bank is performing a chipTAN test. The fake instructions request that the user generate a TAN for the purpose of this “test” and enter the TAN.

These are the instructions through which it steals user information, as they appear in German:

Stecken Sie Ihre Chipkarte in den TAN-Generator und drücken “F.” Halten Sie den TAN-Generator vor die animierte Grafik. Dabei müssen die Markierungen (Dreiecke) von der Grafik mit denen auf Ihrem TAN-Generator übereinstimmen. Prüfen Sie die Anzeige auf dem Leserdisplay und drücken “OK.” Prüfen Sie die Hinweise (Empfänger-Kontonummer (ohne führende Nullen), Bankleitzahl des Empfängers und Betrag) auf dem Leserdisplay und bestätigen diese dann jeweils mit “OK” auf Ihrem TAN-Generator. Hinweis: Uberprufen Sie die Anzeige des TAN-Generators immer anhand der Original-Transaktions-Daten – z.B. einer Rechnung.

Translated to English, the text reads:

Insert your smart card into the TAN generator and press “F.” Place the TAN generator next to the animated graphic on your computer screen. Here, the markings (triangles) of the graph correspond to those on your TAN generator. Check the display on the reader display, and press “OK.” Check the transaction details (recipient’s account number, recipient’s bank and amount of the transfer) on the reader screen and then confirm by clicking “OK” on your TAN generator. Note: Also check the display of the TAN generator always using the original transaction data — for example, an invoice.

Tatanga then captures the TAN entered by the user at the bank site and proceeds to make a transaction in the background. Meanwhile, it replaces the user transaction history/balance details to hide the fraudulent activities from the victim.

The Need for Endpoint Protection

ChipTAN systems are considered fairly secure because the generated TAN takes into account both transaction details and the bank-issued chip and PIN card. However, this attack demonstrates that by using Man in the Browser (MitB) social engineering techniques, financial malware can circumvent chipTAN security. Implementing endpoint protection against advanced malware like Tatanga, Zeus and others is the only way to make sure the integrity of second-factor security measures like chipTAN are not compromised.

More from Malware

Ongoing ITG05 operations leverage evolving malware arsenal in global campaigns

13 min read - Summary As of March 2024, X-Force is tracking multiple ongoing ITG05 phishing campaigns featuring lure documents crafted to imitate authentic documents of government and non-governmental organizations (NGOs) in Europe, the South Caucasus, Central Asia, and North and South America. The uncovered lures include a mixture of internal and publicly available documents, as well as possible actor-generated documents associated with finance, critical infrastructure, executive engagements, cyber security, maritime security, healthcare, business, and defense industrial production. Beginning in November 2023, X-Force observed…

X-Force Threat Intelligence Index 2024 reveals stolen credentials as top risk, with AI attacks on the horizon

4 min read - Every year, IBM X-Force analysts assess the data collected across all our security disciplines to create the IBM X-Force Threat Intelligence Index, our annual report that plots changes in the cyber threat landscape to reveal trends and help clients proactively put security measures in place. Among the many noteworthy findings in the 2024 edition of the X-Force report, three major trends stand out that we’re advising security professionals and CISOs to observe: A sharp increase in abuse of valid accounts…

Hive0051’s large scale malicious operations enabled by synchronized multi-channel DNS fluxing

12 min read - For the last year and a half, IBM X-Force has actively monitored the evolution of Hive0051’s malware capabilities. This Russian threat actor has accelerated its development efforts to support expanding operations since the onset of the Ukraine conflict. Recent analysis identified three key changes to capabilities: an improved multi-channel approach to DNS fluxing, obfuscated multi-stage scripts, and the use of fileless PowerShell variants of the Gamma malware. As of October 2023, IBM X-Force has also observed a significant increase in…

Topic updates

Get email updates and stay ahead of the latest threats to the security landscape, thought leadership and research.
Subscribe today