Meredith L. Patterson

PKI layer cake: new collision attacks against the global x.509 infrastructure

Research unveiled in December of 2008 [15] showed how MD5’s long-known flaws could be actively exploited to attack the real-worldCertification Authority infrastructure. In this paper, we demonstrate two new classes of collision, which will be somewhat trickier to address than previous attacks against X.509: the applicability of MD2 preimage attacks against the primary root certificate for Verisign, and the difficulty of validating X.509 Names contained within PKCS#10 Certificate Requests.We also draw particular attention to two possibly unrecognized vectors for implementation flaws that have been problematic in the past: the ASN.1 BER decoder required to parsePKCS#10, and the potential for SQL injection fromtext contained within its requests. Finally, we explore why the implications of these attacks are broader than some have realized — first, because Client Authentication is sometimes tied to X.509, and second, because Extended Validation certificates were only intended to stop phishing attacks from names similar to trusted brands. As per the work of Adam Barth and Collin Jackson [4], EV does not prevent an attacker who can synthesize or acquire a “low assurance” certificate for a given name from acquiring the “green bar” EV experience.

The Seven Turrets of Babel: A Taxonomy of LangSec Errors and How to Expunge Them

Input-handling bugs share two common patterns: insufficient recognition, where input-checking logic is unfit to validate a programs assumptions about inputs, %leading to the code acting on invalid inputs, and parser differentials, wherein two or more components of a system fail to interpret input equivalently. We argue that these patterns are artifacts of avoidable weaknesses in the development process and explore these patterns both in general and via recent CVE instances. We break ground on defining the input-handling code weaknesses that should be actionable findings and propose a refactoring of existing CWEs to accommodate them. We propose a set of new CWEs to name such weaknesses that will help code auditors and penetration testers precisely express their findings of likely vulnerable code structures.

Beyond Planted Bugs in "Trusting Trust": The Input-Processing Frontier

Big data is changing the landscape of security tools for network monitoring, security information and event management, and forensics; however, in the eternal arms race of attack and defense, security researchers must keep exploring novel ways to mitigate and contain sophisticated attackers.

Implementing a vertically hardened DNP3 control stack for power applications

We present an assurance methodology for producing significantly more secure implementations of SCADA/ICS protocols, and describe our case study of applying it to DNP3, in the form of a filtering proxy that deeply and exhaustively validates DNP3 messages. Unlike the vast majority of deployed proprietary DNP3 implementations, our code demonstrates resilience to state-of-the-art black-box as well as white-box fuzz-testing tools.

Input Handling Done Right: Building Hardened Parsers Using Language-Theoretic Security

Input-handling vulnerabilities have been a constant source of security problems for decades. Many famous recent bugs are in fact input-handling bugs. We argue that the techniques for writing parsers in its present form are insufficient, and hence we propose a new pattern. In this tutorial, we will show participants a new design pattern for designing and implementing parsers using this new method. Participants will witness how this new method leads to more readable code that is easier to audit - while also inherently preventing many input-handling mistakes and having a small CPU footprint.