Visible to the public Biblio

Filters: Author is Holz, T.  [Clear All Filters]
2014-09-26
Becher, M., Freiling, F.C., Hoffmann, J., Holz, T., Uellenbeck, S., Wolf, C..  2011.  Mobile Security Catching Up? Revealing the Nuts and Bolts of the Security of Mobile Devices Security and Privacy (SP), 2011 IEEE Symposium on. :96-111.

We are currently moving from the Internet society to a mobile society where more and more access to information is done by previously dumb phones. For example, the number of mobile phones using a full blown OS has risen to nearly 200% from Q3/2009 to Q3/2010. As a result, mobile security is no longer immanent, but imperative. This survey paper provides a concise overview of mobile network security, attack vectors using the back end system and the web browser, but also the hardware layer and the user as attack enabler. We show differences and similarities between "normal" security and mobile security, and draw conclusions for further research opportunities in this area.

2017-12-12
Kollenda, B., Göktaş, E., Blazytko, T., Koppe, P., Gawlik, R., Konoth, R. K., Giuffrida, C., Bos, H., Holz, T..  2017.  Towards Automated Discovery of Crash-Resistant Primitives in Binary Executables. 2017 47th Annual IEEE/IFIP International Conference on Dependable Systems and Networks (DSN). :189–200.

Many modern defenses rely on address space layout randomization (ASLR) to efficiently hide security-sensitive metadata in the address space. Absent implementation flaws, an attacker can only bypass such defenses by repeatedly probing the address space for mapped (security-sensitive) regions, incurring a noisy application crash on any wrong guess. Recent work shows that modern applications contain idioms that allow the construction of crash-resistant code primitives, allowing an attacker to efficiently probe the address space without causing any visible crash. In this paper, we classify different crash-resistant primitives and show that this problem is much more prominent than previously assumed. More specifically, we show that rather than relying on labor-intensive source code inspection to find a few "hidden" application-specific primitives, an attacker can find such primitives semi-automatically, on many classes of real-world programs, at the binary level. To support our claims, we develop methods to locate such primitives in real-world binaries. We successfully identified 29 new potential primitives and constructed proof-of-concept exploits for four of them.

2020-11-09
Göktaş, E., Kollenda, B., Koppe, P., Bosman, E., Portokalidis, G., Holz, T., Bos, H., Giuffrida, C..  2018.  Position-Independent Code Reuse: On the Effectiveness of ASLR in the Absence of Information Disclosure. 2018 IEEE European Symposium on Security and Privacy (EuroS P). :227–242.
Address-space layout randomization is a wellestablished defense against code-reuse attacks. However, it can be completely bypassed by just-in-time code-reuse attacks that rely on information disclosure of code addresses via memory or side-channel exposure. To address this fundamental weakness, much recent research has focused on detecting and mitigating information disclosure. The assumption being that if we perfect such techniques, we will not only maintain layout secrecy but also stop code reuse. In this paper, we demonstrate that an advanced attacker can mount practical code-reuse attacks even in the complete absence of information disclosure. To this end, we present Position-Independent Code-Reuse Attacks, a new class of codereuse attacks relying on the relative rather than absolute location of code gadgets in memory. By means of memory massaging, the attacker first makes the victim program generate a rudimentary ROP payload (for instance, containing code pointers that target instructions "close" to relevant gadgets). Afterwards, the addresses in this payload are patched with small offsets via relative memory writes. To establish the practicality of such attacks, we present multiple Position-Independent ROP exploits against real-world software. After showing that we can bypass ASLR in current systems without requiring information disclosures, we evaluate the impact of our technique on other defenses, such as fine-grained ASLR, multi-variant execution, execute-only memory and re-randomization. We conclude by discussing potential mitigations.