Riccardo Paccagnella (University of Illinois at Urbana–Champaign), Pubali Datta (University of Illinois at Urbana–Champaign), Wajih Ul Hassan (University of Illinois at Urbana–Champaign), Adam Bates (University of Illinois at Urbana–Champaign), Christopher W. Fletcher (University of Illinois at Urbana–Champaign), Andrew Miller (University of Illinois at Urbana–Champaign), Dave Tian (Purdue University)

System auditing is a central concern when investigating and responding to security incidents. Unfortunately, attackers regularly engage in anti-forensic activities after a break-in, covering their tracks from the system logs in order to frustrate the efforts of investigators. While a variety of tamper-evident logging solutions have appeared throughout the industry and the literature, these techniques do not meet the operational and scalability requirements of system-layer audit frameworks.

In this work, we introduce Custos, a practical framework for the detection of tampering in system logs. Custos consists of a tamper-evident logging layer and a decentralized auditing protocol. The former enables the verification of log integrity with minimal changes to the underlying logging framework, while the latter enables near real-time detection of log integrity violations within an enterprise-class network. Custos is made practical by the observation that we can decouple the costs of cryptographic log commitments from the act of creating and storing log events, without trading off security, leveraging features of off-the-shelf trusted execution environments. Supporting over one million events per second, we show that Custos' tamper-evident logging protocol is three orders of magnitude (1000×) faster than prior solutions and incurs only between 2% and 7% runtime overhead over insecure logging on intensive workloads. Further, we show that Custos' auditing protocol can detect violations in near real-time even in the presence of a powerful distributed adversary and with minimal (3%) network overhead. Our case study on a real-world APT attack scenario demonstrates that Custos forces anti-forensic attackers into a "lose-lose" situation, where they can either be covert and not tamper with logs (which can be used for forensics), or erase logs but then be detected by Custos.

View More Papers

Let's Revoke: Scalable Global Certificate Revocation

Trevor Smith (Brigham Young University), Luke Dickenson (Brigham Young University), Kent Seamons (Brigham Young University)

Read More

ConTExT: A Generic Approach for Mitigating Spectre

Michael Schwarz (Graz University of Technology), Moritz Lipp (Graz University of Technology), Claudio Canella (Graz University of Technology), Robert Schilling (Graz University of Technology and Know-Center GmbH), Florian Kargl (Graz University of Technology), Daniel Gruss (Graz University of Technology)

Read More

ProtectIOn: Root-of-Trust for IO in Compromised Platforms

Aritra Dhar (ETH Zurich), Enis Ulqinaku (ETH Zurich), Kari Kostiainen (ETH Zurich), Srdjan Capkun (ETH Zurich)

Read More

Dynamic Searchable Encryption with Small Client Storage

Ioannis Demertzis (University of Maryland), Javad Ghareh Chamani (Hong Kong University of Science and Technology & Sharif University of Technology), Dimitrios Papadopoulos (Hong Kong University of Science and Technology), Charalampos Papamanthou (University of Maryland)

Read More