SMS-Based One-Time Passwords: Attacks and Defense

(Short Paper)
  • Collin Mulliner
  • Ravishankar Borgaonkar
  • Patrick Stewin
  • Jean-Pierre Seifert
Part of the Lecture Notes in Computer Science book series (LNCS, volume 7967)


SMS-based One-Time Passwords (SMS OTP) were introduced to counter phishing and other attacks against Internet services such as online banking. Today, SMS OTPs are commonly used for authentication and authorization for many different applications. Recently, SMS OTPs have come under heavy attack, especially by smartphone Trojans. In this paper, we analyze the security architecture of SMS OTP systems and study attacks that pose a threat to Internet-based authentication and authorization services. We determined that the two foundations SMS OTP is built on, cellular networks and mobile handsets, were completely different at the time when SMS OTP was designed and introduced. Throughout this work, we show why SMS OTP systems cannot be considered secure anymore. Based on our findings, we propose mechanisms to secure SMS OTPs against common attacks and specifically against smartphone Trojans.


Smartphone OTP SMS mTAN Malware Multi-factor 


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Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Collin Mulliner
    • 1
  • Ravishankar Borgaonkar
    • 2
  • Patrick Stewin
    • 2
  • Jean-Pierre Seifert
    • 2
  1. 1.Northeastern UniversityUSA
  2. 2.Technische Universität BerlinGermany

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