Teemu Rytilahti (Ruhr University Bochum), Thorsten Holz (Ruhr University Bochum)

Typical port scanning approaches do not achieve a full coverage of all devices connected to the Internet as not all devices are directly reachable via a public (IPv4) address: due to IP address space exhaustion, firewalls, and many other reasons, an end-to-end connectivity is not achieved in today’s Internet anymore. Especially Network Address Translation (NAT) is widely deployed in practice and it has the side effect of “hiding” devices from being scanned. Some protocols, however, require end-to-end connectivity to function properly and hence several methods were developed in the past to enable crossing network borders.

In this paper, we explore how an attacker can take advantage of such application-layer middlebox protocols to access devices hidden behind these gateways. More specifically, we investigate different methods for identifying such devices by (ab)using legitimate protocol features. We categorize the available protocols into two classes: First, there are persistent protocols that are typically port forwarding based. Such protocols are used to allow local network devices to open and forward external ports to them. Second, there are non-persistent protocols that are typically proxy-based to route packets between network edges, such as HTTP and SOCKS proxies. We perform a comprehensive, Internet-wide analysis to obtain an accurate overview of how prevalent and widespread such protocols are in practice. Our results indicate that hundreds of thousands of hosts are vulnerable for different types of attacks, e. g., we detect over 400.000 hosts that are likely vulnerable for attacks involving the UPnP IGD protocol. More worrisome, we find empirical evidence that attackers are already actively exploiting such protocols in the wild to access devices located behind NAT gateways. Amongst other findings, we discover that at least 24 % of all open Internet proxies are misconfigured to allow accessing hosts on non-routable addresses.

View More Papers

SPEECHMINER: A Framework for Investigating and Measuring Speculative Execution...

Yuan Xiao (The Ohio State University), Yinqian Zhang (The Ohio State University), Radu Teodorescu (The Ohio State University)

Read More

On the Resilience of Biometric Authentication Systems against Random...

Benjamin Zi Hao Zhao (University of New South Wales and Data61 CSIRO), Hassan Jameel Asghar (Macquarie University and Data61 CSIRO), Mohamed Ali Kaafar (Macquarie University and Data61 CSIRO)

Read More

CloudLeak: Large-Scale Deep Learning Models Stealing Through Adversarial Examples

Honggang Yu (University of Florida), Kaichen Yang (University of Florida), Teng Zhang (University of Central Florida), Yun-Yun Tsai (National Tsing Hua University), Tsung-Yi Ho (National Tsing Hua University), Yier Jin (University of Florida)

Read More

Unicorn: Runtime Provenance-Based Detector for Advanced Persistent Threats

Xueyuan Han (Harvard University), Thomas Pasquier (University of Bristol), Adam Bates (University of Illinois at Urbana-Champaign), James Mickens (Harvard University), Margo Seltzer (University of British Columbia)

Read More