Stephan Kleber

Stephan Kleber graduated from his studies of computer science at the University of Ulm in 2011 as Master of Science. Until 2012, he worked at the data processing service center of the University Medical Center Ulm (ZIK). During this time he also supervised courses and theses at the Institute of Media Informatics in the areas IT-Security and Privacy. 2012/2013 he worked in cooperation with the Institute of Information Resource Management and the Institute of Distributed Systems as research assistant in the bwGRiD-Portalproject.

Since 2013, he is research assistant at the Institute of Distributed Systems.

Research

I am interested in Security and Privacy in IT-Systems in general.

My emphasis lies in the areas:

  • Analysis of network protocols and Protocol Reverse Engineering
  • Usage of Physical(ly) Unclonable Functions (PUFs)
  • Security of wireless communications, especially of Implantable Medical Devices (IMDs)

Besides that my further interests are:

  • Security and forensics of mobile devices
  • Privacy implications on unsing mobile devices
  • Malware analyses
  • Penetration testing
  • Security of web technologies

Since 2008 I participated in the iCTF of UCSB with the team Ulm Security Sparrows of the University of Ulm on a regular basis.

Publications


Kleber, Stephan; Unterstein, Florian; Matousek, Matthias; Kargl, Frank; Slomka, Frank; Hiller, Matthias
Design of the Secure Execution PUF-based Processor (SEPP)
Workshop on Trustworthy Manufacturing and Utilization of Secure Devices, TRUDEVICE 2015
September 2015

Abstract: A persistent problem with program execution is its vulnerability to code injection attacks. Equally unsolved is the susceptibility of software to reverse engineering, which undermines code confidentiality. We propose an approach that solves both kinds of security problems by employing instruction-level code encryption combined with the use of a physical unclonable function (PUF). Our Secure Execution PUF-based Processor (SEPP) architecture is designed to minimize the attack surface, as well as the performance impact, and requires no significant changes to the software development process. Our approach supports distributed systems, as the secure execution environment needs not be physically available to the developer.

Kleber, Stephan; Unterstein, Florian; Matousek, Matthias; Kargl, Frank; Slomka, Frank; Hiller, Matthias
Secure Execution Architecture based on PUF-driven Instruction Level Code Encryption
IACR,
July 2015

Abstract: A persistent problem with program execution, despite numerous mitigation attempts, is its inherent vulnerability to the injection of malicious code. Equally unsolved is the susceptibility of firmware to reverse engineering, which undermines the manufacturer's code confidentiality. We propose an approach that solves both kinds of security problems employing instruction-level code encryption combined with the use of a physical unclonable function (PUF). Our novel Secure Execution PUF-based Processor (SEPP) architecture is designed to minimize the attack surface, as well as performance impact, and requires no significant changes to the development process. This is possible based on a tight integration of a PUF directly into the processor's instruction pipeline. Furthermore, cloud scenarios and distributed embedded systems alike inherently depend on remote execution; our approach supports this, as the secure execution environment needs not to be locally available at the developers site. We implemented an FPGA-based prototype based on the OpenRISC Reference Platform. To assess our results, we performed a security analysis of the processor and evaluated the performance impact of the encryption. We show that the attack surface is significantly reduced compared to previous approaches while the performance penalty is at a reasonable factor of about 1.5.

Kleber, Stephan; van der Heijden, Rens W.; Kopp, Henning; Kargl, Frank
Terrorist fraud resistance of distance bounding protocols employing physical unclonable functions
Networked Systems (NetSys), 2015 International Conference and Workshops on , page 1-8.
Publisher: IEEE,
March 2015

Abstract: Distance bounding protocols (DBPs) are security protocols that aim to limit the maximum possible distance between two partners in a wireless communication. This enables to ensure locality of interaction between two devices. Despite numerous proposed protocols, recent analyses of DBPs have shown the majority of them to be susceptible to attacks. Most prominent among the unsolved security problems of DBPs is terrorist fraud. This type of attack involves collaboration with a legitimate device, after which the attacker can successfully execute the protocol. We show how terrorist fraud can be prevented by replacing shared secrets - commonly used in classical DBPs - with physical unclonable functions (PUFs). Our new approach can be integrated in all current DBPs with minor modifications. We offer two alternate designs: One utilizing challenge-response PUFs and another using so-called SIMPL systems, a PUF-analogue to public-key cryptography. We use a security model proposed by previous work to demonstrate security of our scheme.

Patzlaff, Heiko; Kleber, Stephan
Working Groups Report: Cyberforensics
In Marc Dacier and Frank Kargl and Hartmut König and Alfonso Valdes, editor, Network Attack Detection and Defense: Securing Industrial Control Systems for Critical Infrastructures Volume 14292 of Report from Dagstuhl Seminar
Chapter 5.4, page 75--77.
Publisher: Dagstuhl Publishing, Germany,
2014

Teaching

Supervision of theses

Gladly, I take the supervision of bachelor's, master's and diploma theses from any area of my research. Suggested topics can be found under Theses. Own propositions are welcome.

Excercises for Lectures

(Pro-)Seminars, Praktica und Project Modules

Appointments

Please make an appointment by email.