Vulnerability Analysis

05 April 2017, 11:00, A6-007

Session chair: Manuel Egele, Boston University, USA

Pinpointing Vulnerabilities

Yue Chen, Mustakimur Khandaker, Zhi Wang

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Memory-based vulnerabilities are a major source of attack vectors. They allow attackers to gain unauthorized access to computers and their data. Previous research has made significant progress in detecting attacks. However, developers still need to locate and fix these vulnerabilities, a mostly manual and time-consuming process. They face a number of challenges. Particularly, the manifestation of an attack does not always coincide with the exploited vulnerabilities, and many attacks are hard to reproduce in the lab environment, leaving developers with limited information to locate them. In this paper, we propose Ravel, an architectural approach to pinpoint vulnerabilities from attacks. Ravel consists of an online attack detector and an offline vulnerability locator linked by a record & replay mechanism. Specifically, Ravel records the execution of a production system and simultaneously monitors it for attacks. If an attack is detected, the execution is replayed to reveal the targeted vulnerabilities by analyzing the program’s memory access patterns under attack. We have built a prototype of Ravel based on the open-source FreeBSD operating system. The evaluation results in security and performance demonstrate that Ravel can effectively pinpoint various types of memory vulnerabilities and has low performance overhead.

Extracting Conditional Formulas for Cross-Platform Bug Search

Qian Feng, Minghua Wang, Mu Zhang, Rundong Zhou, Andrew Henderson, Heng Yin

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With the recent increase in security breaches in embedded systems and IoT devices, it becomes increasingly important to search for vulnerabilities directly in binary executables in a cross-platform setting. However, very little has been explored in this domain. The existing efforts are prone to producing considerable false positives, and their results cannot provide explainable evidence for human analysts to eliminate these false positives. In this paper, we propose to extract conditional formulas as higher-level semantic features from the raw binary code to conduct the code search. A conditional formula explicitly captures two cardinal factors of a bug: 1) erroneous data dependencies and 2) missing or invalid condition checks. As a result, binary code search on conditional formulas produces significantly higher accuracy and provide meaningful evidence for human analysts to further examine the search results. We have implemented a prototype, \codename, and evaluated it using well-known software, including {\tt OpenSSL} and {\tt BusyBox}. Experimental results have shown that \codename outperforms the existing bug search techniques in terms of accuracy. Moreover, by evaluating 5 recent vulnerabilities, \codename provides clear evidence for human analysts to determine if a matched candidate is indeed vulnerable or has been patched.

Discovering Logical Vulnerabilities in the Wi-Fi Handshake Using Model-Based Testing

Mathy Vanhoef, Domien Schepers, Frank Piessens

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We use model-based testing techniques to detect logical vulnerabilities in implementations of the Wi-Fi handshake. This reveals new fingerprinting techniques, multiple downgrade attacks, and Denial of Service (DoS) vulnerabilities. Stations use the Wi-Fi handshake to securely connect with wireless networks. In this handshake, mutually supported capabilities are determined, and fresh pairwise keys are negotiated. As a result, a proper implementation of the Wi-Fi handshake is essential in protecting all subsequent traffic. To detect the presence of erroneous behaviour, we propose a model-based technique that generates a set of representative test cases. These tests cover all states of the Wi-Fi handshake, and explore various edge cases in each state. We then treat the implementation under test as a black box, and execute all generated tests. Determining whether a failed test introduces a security weakness is done manually. We tested 12 implementations using this approach, and discovered irregularities in all of them. Our findings include fingerprinting mechanisms, DoS attacks, and downgrade attacks where an adversary can force usage of the insecure WPA-TKIP cipher. Finally, we explain how one of our downgrade attacks highlights incorrect claims made in the 802.11 standard.