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Conference:  Defcon 31
Authors: Omer Attias Security Researcher at SafeBreach

Public transportation payment systems have undergone significant changes over the years. Recently, mobile payment solutions have become increasingly popular, allowing passengers to pay for their fare using their smartphones or other mobile devices. The evolution of public transportation payment systems has been driven by the need for faster, more convenient, and more secure payment methods, and this trend is likely to continue in the years to come, But how secure are mobile payment solutions for public transportation? In this presentation, we will examine the security risks associated with transportation applications, using Moovit as a case study. Moovit is a widely used transportation app operating in over 100 countries and 5000+ cities. Through our investigation of the app's API, including SSL-encrypted data, we discovered specific vulnerabilities, which we will discuss. We will also demonstrate a custom user interface that can obtain a "free ticket" and cause someone else to pay. Furthermore, we will explain how an attacker could gain unauthorized access to and exfiltrate Personal Identifiable Information (PII) of registered users. Our findings offer practical recommendations to improve the security of transportation apps.
Conference:  Defcon 31
Authors: Bill Demirkapi Microsoft Security Response Center

Digital signatures are fundamental for verifying the authenticity and integrity of untrusted data in the digital world. They ensure that software, firmware, and other digital content are not tampered with during transmission or at rest. Code signing certificates are significantly more challenging to obtain when compared to alternatives like SSL or S/MIME certificates. The latter only has a single criterion- proof of control over a domain, while the former requires significant validation of the publisher itself. This project uncovered a systemic vulnerability present in numerous signature validation implementations, enabling attackers to exploit valid certificates in an unintended manner. Vulnerable implementations mistakenly perceive files signed with incompatible certificates as legitimate, violating their respective specifications and allowing threat actors to sign untrusted code at little to no cost. In this talk, we will explore the problem at all levels, ranging from the fundamental theory to its application across multiple formats and real-world situations.