손수엘 교수

The OpenFlow (OF) switching specification represents an innovative and open standard for enabling the dynamic programming of flow control policies in production networks. Unfortunately, thus far researchers have paid little attention to the development of methods for verifying that dynamic flow policies inserted within an OpenFlow network do not violate the network's underlying security policy. We introduce Flover, a model checking system which verifies that the aggregate of flow policies instan

The Dark Web is notorious for being a major distribution channel of harmful content as well as unlawful goods.Perpetrators have also used cryptocurrencies to conduct illicit financial transactions while hiding their identities.The limited coverage and outdated data of the Dark Web in previous studies motivated us to conduct an in-depth investigative study to understand how perpetrators abuse cryptocurrencies in the Dark Web.We designed and implemented MFScope, a new framework which collects Dark

Binary code similarity analysis (BCSA) is widely used for diverse security applications such as plagiarism detection, software license violation detection, and vulnerability discovery. Despite the surging research interest in BCSA, it is significantly challenging to perform new research in this field for several reasons. First, most existing approaches focus only on the end results, namely, increasing the success rate of BCSA by adopting uninterpretable machine learning. Moreover, they utilize t

We analyze the software stack of popular mobile advertising libraries on Android and investigate how they protect the users of advertising-supported apps from malicious advertising. We find that, by and large, Android advertising libraries properly separate the privileges of the ads from the host app by confining ads to dedicated browser instances that correctly apply the same origin policy.

Web applications written in languages such as PHP and JSP are notoriously vulnerable to accidentally omitted authorization checks and other security bugs. Existing techniques that find missing security checks in library and system code assume that (1) security checks can be recognized syntactically and (2) the same pattern of checks applies universally to all programs. These assumptions do not hold for Web applications. Each Web application uses different variables and logic to check the user's

Code injection attacks continue to plague applications that incorporate user input into executable programs. For example, SQL injection vulnerabilities rank fourth among all bugs reported in CVE, yet all previously proposed methods for detecting SQL injection attacks suffer from false positives and false negatives.

The postMessage mechanism in HTML5 enables Web content from different origins to communicate with each other, thus relaxing the same origin policy. It is especially popular in websites that include third-party content. Each message contains accurate information about its origin, but the receiver must check this information before accepting the message. The responsibility for preventing cross-origin attacks is thus partially delegated from the Web browser to the implementors of postMessage receiv

Access-control policies in Web applications ensure that only authorized users can perform security-sensitive operations. These policies usually check user credentials before executing actions such as writing to the database or navigating to privileged pages. Typically, every Web application uses its own, hand-crafted program logic to enforce access control. Within a single application, this logic can vary between different user roles, e.g., administrator or regular user. Unfortunately, developer

Web applications are vulnerable to semantic attacks such as denial of service due to infinite loops caused by malicious inputs and unauthorized database operations due to missing security checks. Unlike "conventional" threats such as SQL injection and cross-site scripting, these attacks exploit bugs in the logic of the vulnerable application and cannot be discovered using data-flow analysis alone.

Progressive Web App (PWA) is a new generation of Web application designed to provide native app-like browsing experiences even when a browser is offline. PWAs make full use of new HTML5 features which include push notification, cache, and service worker to provide short-latency and rich Web browsing experiences. We conduct the first systematic study of the security and privacy aspects unique to PWAs. We identify security flaws in main browsers as well as design flaws in popular third-party push

JavaScript (JS) engine vulnerabilities pose significant security threats affecting billions of web browsers. While fuzzing is a prevalent technique for finding such vulnerabilities, there have been few studies that leverage the recent advances in neural network language models (NNLMs). In this paper, we present Montage, the first NNLM-guided fuzzer for finding JS engine vulnerabilities. The key aspect of our technique is to transform a JS abstract syntax tree (AST) into a sequence of AST subtree

Phishing attacks are causing substantial damage albeit extensive effort in academia and industry. Recently, a large volume of phishing attacks transit toward adopting HTTPS, leveraging TLS certificates issued from Certificate Authorities (CAs), to make the attacks more effective. In this paper, we present a comprehensive study on the security practices of CAs in the HTTPS phishing ecosystem. We focus on the CAs, critical actors under-studied in previous literature, to better understand the impor

Black-box web scanners have been a prevalent means of performing penetration testing to find reflected cross-site scripting (XSS) vulnerabilities. Unfortunately, off-the-shelf black-box web scanners suffer from unscalable testing as well as false negatives that stem from a testing strategy that employs fixed attack payloads, thus disregarding the exploitation of contexts to trigger vulnerabilities. To this end, we propose a novel method of adapting attack payloads to a target reflected XSS vulne

An Unrestricted File Upload (UFU) vulnerability is a critical security threat that enables an adversary to upload her choice of a forged file to a target web server. This bug evolves into an Unrestricted Executable File Upload (UEFU) vulnerability when the adversary is able to conduct remote code execution of the uploaded file via triggering its URL. We design and implement FUSE, a penetration testing tool designed to discover UFU and UEFU vulnerabilities in server-side PHP web applications. The