No Arabic abstract
Automatic patch generation can significantly reduce the window of exposure after a vulnerability is disclosed. Towards this goal, a long-standing problem has been that of patch localization: to find a program point at which a patch can be synthesized. We present PatchLoc, one of the first systems which automatically identifies such a location in a vulnerable binary, given just one exploit, with high accuracy. PatchLoc does not make any assumptions about the availability of source code, test suites, or specialized knowledge of the vulnerability. PatchLoc pinpoints valid patch locations in large real-world applications with high accuracy for about 88% of 43 CVEs we study. These results stem from a novel approach to automatically synthesizing a test-suite which enables probabilistically ranking and effectively differentiating between candidate program patch locations.
With the increasing usage of open-source software (OSS) components, vulnerabilities embedded within them are propagated to a huge number of underlying applications. In practice, the timely application of security patches in downstream software is challenging. The main reason is that such patches do not explicitly indicate their security impacts in the documentation, which would be difficult to recognize for software maintainers and users. However, attackers can still identify these secret security patches by analyzing the source code and generate corresponding exploits to compromise not only unpatch
Android Framework is a layer of software that exists in every Android system managing resources of all Android apps. A vulnerability in Android Framework can lead to severe hacks, such as destroying user data and leaking private information. With tens of millions of Android devices unpatched due to Android fragmentation, vulnerabilities in Android Framework certainly attract attackers to exploit them. So far, enormous manual effort is needed to craft such exploits. To our knowledge, no research has been done on automatic generation of exploits that take advantage of Android Framework vulnerabilities. We make a first step towards this goal by applying symbolic execution of Android Framework to finding bugs and generating exploits. Several challenges have been raised by the task. (1) The information of an app flows to Android Framework in multiple intricate steps, making it difficult to identify symbolic inputs. (2) Android Framework has a complex initialization phase, which exacerbates the state space explosion problem. (3) A straightforward design that builds the symbolic executor as a layer inside the Android system will not work well: not only does the implementation have to ensure the compatibility with the Android system, but it needs to be maintained whenever Android gets updated. We present novel ideas and techniques to resolve the challenges, and have built the first system for symbolic execution of Android Framework. It fundamentally changes the state of the art in exploit generation on the Android system, and has been applied to constructing new techniques for finding vulnerabilities.
A fundamental premise of SMS One-Time Password (OTP) is that the used pseudo-random numbers (PRNs) are uniquely unpredictable for each login session. Hence, the process of generating PRNs is the most critical step in the OTP authentication. An improper implementation of the pseudo-random number generator (PRNG) will result in predictable or even static OTP values, making them vulnerable to potential attacks. In this paper, we present a vulnerability study against PRNGs implemented for Android apps. A key challenge is that PRNGs are typically implemented on the server-side, and thus the source code is not accessible. To resolve this issue, we build an analysis tool, sysname, to assess implementations of the PRNGs in an automated manner without the source code requirement. Through reverse engineering, sysname identifies the apps using SMS OTP and triggers each apps login functionality to retrieve OTP values. It further assesses the randomness of the OTP values to identify vulnerable PRNGs. By analyzing 6,431 commercially used Android apps downloaded from tool{Google Play} and tool{Tencent Myapp}, sysname identified 399 vulnerable apps that generate predictable OTP values. Even worse, 194 vulnerable apps use the OTP authentication alone without any additional security mechanisms, leading to insecure authentication against guessing attacks and replay attacks.
Vulnerability prediction refers to the problem of identifying the system components that are most likely to be vulnerable based on the information gained from historical data. Typically, vulnerability prediction is performed using manually identified features that are potentially linked with vulnerable code. Unfortunately, recent studies have shown that existing approaches are ineffective when evaluated in realistic settings due to some unavoidable noise included in the historical data. To deal with this issue, we develop a prediction method using the encoder-decoder framework of machine translation that automatically learns the latent features (context, patterns, etc.) of code that are linked with vulnerabilities. The key idea of our approach is to learn from things we know, the past vulnerability fixes and their context. We evaluate our approach by comparing it with existing techniques on available releases of the three security-critical open source systems (Linux Kernel, OpenSSL, and Wireshark) with historical vulnerabilities that have been reported in the National Vulnerability Database (NVD). Our evaluation demonstrates that the prediction capability of our approach significantly outperforms the state-of-the-art vulnerability prediction techniques (Software Metrics, Imports, Function Calls, and Text Mining) in both recall and precision values (yielding 4.7 times higher MCC values) under realistic training setting.
Despite the high stakes involved in smart contracts, they are often developed in an undisciplined manner, leaving the security and reliability of blockchain transactions at risk. In this paper, we introduce ContraMaster: an oracle-supported dynamic exploit generation framework for smart contracts. Existing approaches mutate only single transactions; ContraMaster exceeds these by mutating the transaction sequences. ContraMaster uses data-flow, control-flow, and the dynamic contract state to guide its mutations. It then monitors the executions of target contract programs, and validates the results against a general-purpose semantic test oracle to discover vulnerabilities. Being a dynamic technique, it guarantees that each discovered vulnerability is a violation of the test oracle and is able to generate the attack script to exploit this vulnerability. In contrast to rule-based approaches, ContraMaster has not shown any false positives, and it easily generalizes to unknown types of vulnerabilities (e.g., logic errors). We evaluate ContraMaster on 218 vulnerable smart contracts. The experimental results confirm its practical applicability and advantages over the state-of-the-art techniques, and also reveal three new types of attacks.