Fuzzing has been a widely-used technique for discovering software vulnerabilities. Many existing fuzzers leverage coverage-feedback to evolve seeds to maximize (optimize) program branch coverage. Recently, some techniques propose to train deep learning models to predict the branch coverage of an arbitrary input. Those techniques have proved their success in improving coverage and discovering bugs under different experimental settings. However, deep learning models, usually as a black magic box, are notoriously lack of explanation. Moreover, their performance can be sensitive to the collected runtime coverage information for training, indicating potentially unstable performance. To this end, in this work we conduct a systematic and extensive empirical study on 4 types of deep learning models across 6 projects to reproduce the actual performance of deep learning fuzzers, analyze the advantages and disadvantages of deep learning in the process of fuzzing applications, and explore the future direction of the combination of the two. Our empirical results reveal that the deep learning models can only be effective in very limited scenarios, which is largely restrained by training data imbalance, dependant labels, model over-generalization, and the insufficient expressiveness of the state-of-the-art models. Consequently, the estimated gradients by the models to cover a branch can be less helpful in many scenarios.

The continuous discovery of software vulnerabilities have brought great challenges to the cyber security, which will lead to severe systematical or individual losses after being exploited. But the harshly increasing of software vulnerabilities overwhelms the time consuming vulnerability analysis. Security experts must pay more attention to the ones which have the highest priority to be repaired. In general, both severity and exploitability determine the severity of a software vulnerability. Compared with the severity evaluated by the Common Vulnerability Scoring System (CVSS score), the exploitability is still lack of a well-accepted standard. Furthermore, based on the perspective of attack and defense, we found that the exploitability of vulnerabilities is more attractive to hackers so that system or individual is severely affected by the exploitability rather than the severity. In this paper, we propose a deep learning based approach to predict the exploitability of the vulnerability by using the correlated textual description and characteristics. Specifically, our approach takes character-level Convolutional Neural Network (charCNN) to fetch more fine-grained character-level features from the vulnerability description instead of the word-level features considered by the previous literatures. And we highlight the importance of vulnerability characteristics such as Confidentiality Impact, Integrity Impact, Attack Vector etc. during the determination of vulnerability exploitability. Extensive experiments are set to prove the effectiveness of the given charCNN approach through the comparison on both different levels of features and different neural network models. Our approach achieves the best F1 values 93.1% (at least 2.2% more than the baselines). And we also investigate the efficiency of charCNN trained by historical vulnerability when predicting the exploitability of the newly published vulnerabilities. Finally, we further explore the robustness of the proposed model by changing the scale of training sets. For the prediction of vulnerability exploitability, we recommend to adopt 40.0% to 50.0% vulnerabilities to train a robust charCNN model.

Authorship identification is the process of identifying and classifying authors through given codes. Authorship identification can be used in a wide range of software domains, e.g., code authorship disputes, plagiarism detection, exposure of attackers’ identity. Besides the inherent challenges from legacy software development, framework programming and crowdsourcing mode in Android raise the difficulties of authorship identification significantly. More specifically, widespread third party libraries and inherited components (e.g., classes, methods, and variables) dilute the primary code within the entire Android app and blur the boundaries of code written by different authors. However, prior research has not well addressed these challenges.To this end, we design a two-phased approach to attribute the primary code of an Android app to the specific developer. In the first phase, we put forward three types of strategies to identify the relationships between Java packages in an app, which consist of context, semantic and structural relationships. A package aggregation algorithm is developed to cluster all packages that are of high probability written by the same authors. In the second phase, we develop three types of features to capture authors’ coding habits and code stylometry. Based on that, we generate fingerprints for an author from its developed Android apps and employ several machine learning algorithms for authorship classification. We evaluate our approach in three datasets that contain 15,666 apps from 257 distinct developers and achieve a 92.5% accuracy rate on average. Additionally, we test it on 2,900 obfuscated apps and our approach can classify apps with an accuracy rate of 80.4%.

To guarantee the quality of software, specifying security requirements (SRs) is essential for developing systems, especially for security-critical software systems. However, using security threat to determine detailed SR is quite difficult according to Common Criteria (CC), which is too confusing and technical for non-security specialists. In this paper, we propose a Co-occurrence Recommend Model (CoRM) to automatically recommend software SRs. In this model, the security threats of product are extracted from security target documents of software, in which the related security requirements are tagged. In order to establish relationships between software security threat and security requirement, semantic similarities between different security threat is calculated by Skip-thoughts Model. To evaluate our CoRM model, over 1000 security target documents of 9 types software products are exploited. The results suggest that building a CoRM model via semantic similarity is feasible and reliable.

Semantic Annotation plays an essential role in automatic service discovery and composition. However, existing approaches and tools cannot achieve high annotation quality to ensure the semantic service application. Meanwhile, the semi-automatic strategies for improving the annotation quality are time-consuming. To further improve the efficiency as well as the quality of the annotation, this paper presents an effective method involving human-computer interaction to further optimize the annotation procedure. Besides employing the feedback and propagation strategy to semi-automatically improve the annotation quality, the strategy to involve the manual annotation is developed when the efficiency of semi-automatically strategy is related low. To optimize the manual annotation procedure, a clustering based approach is presented to select the most impacted candidates to optimize the annotation improvement. In addition, to help the annotators to choose the correct annotation, the local ontology restriction based method is further designed to improve the recommendation performance. The experiments show that our approach effectively involving the human intervention can significantly improve the annotation quality, faster the quality improvement procedure and reduce the manual load by increasing the recommendation accuracy.

An improved unit module of a novel mobile self-assembling modular robotic system is presented in this paper. Two continuous rotational DoFs are used in each module to implement both valuable self-locomotion and flexible reconfiguration. To achieve efficient exploration, unit module can implement two-dimensional locomotion independently and freely in a range of surface conditions in real world, even in environments with certain terrain challenges. With the help of three active connection mechanisms (ACMs), the module has great potential in assembling and reconfiguration to form complex three-dimensional structures. Preliminary locomotion tests in different environments demonstrate its effective mobility and potential applications for exploration. Several useful and easy realized configurations are explained with simulations at last.