A lot of malicious applications appears every day, threatening numerous users. Therefore, a surge of studies have been conducted to protect users from newly emerging malware by using machine learning algorithms. Albeit existing machine or deep learning-based Android malware detection approaches achieve high accuracy by using a combination of multiple features, it is not possible to employ them on our mobile devices due to the high cost for using them. In this paper, we proposeMAPAS, a malware detection system, that achieves high accuracy and adaptable usages of computing resources.MAPASanalyzes behaviors of malicious applications based on API call graphs of them by using convolution neural networks (CNN). However,MAPASdoes not use a classifier model generated by CNN, it only utilizes CNN for discovering common features of API call graphs of malware. For efficiently detecting malware,MAPASemploys a lightweight classifier that calculates a similarity between API call graphs used for malicious activities and API call graphs of applications that are going to be classified. To demonstrate the effectiveness and efficiency ofMAPAS, we implement a prototype and thoroughly evaluate it. And, we compareMAPASwith a state-of-the-art Android malware detection approach, MaMaDroid. Our evaluation results demonstrate thatMAPAScan classify applications 145.8% faster and uses memory around ten times lower than MaMaDroid. Also,MAPASachieves higher accuracy (91.27%) than MaMaDroid (84.99%) for detecting unknown malware. In addition,MAPAScan generally detect any type of malware with high accuracy.

Although anyone can easily publish Android applications (or apps) in an app marketplace according to an open policy, decompiling the apps is also easy due to the structural characteristics of the app building process, making them very vulnerable to forgery or modification attacks. In particular, users may suffer direct financial loss if this vulnerability is exploited in security-critical private and business applications, such as online banking. In this paper, some of the major Android-based smartphone banking apps in Korea being distributed on either the Android Market or the third party market were tested to verify whether a money transfer could be made to an unintended recipient. The experimental results with real Android banking apps showed that an attack of this kind is possible without having to illegally obtain any of the sender’s personal information, such as the senders public key certificate, the password to their bank account, or their security card. In addition, the cause of this vulnerability is analyzed and some technical countermeasures are discussed.

Peer-to-peer systems enable efficient resource aggregation and are inherently scalable since they do not depend on any centralized authority. However, lack of a centralized authority prompts many security-related challenges. Providing efficient security services in these systems is an active research topic which is receiving much attention in the security research community. In this paper, we explore the use of threshold cryptography in peer-to-peer settings (both Internet- and MANET-based) to provide, in a robust and fault tolerant fashion, security services such as authentication, certificate issuance and access control. Threshold cryptography provides high availability by distributing trust throughout the group and is, therefore, an attractive solution for secure peer-groups. Our work investigates the applicability of threshold cryptography for membership control in peer-to-peer systems. In the process, we discover that one interesting proposed scheme contains an unfortunate (yet serious) flaw. We then present an alternative solution and its performance measurements. More importantly, our preliminary work casts a certain degree of skepticism on the practicality and even viability of using (seemingly attractive) threshold cryptography in certain peer-to-peer settings.

Admission control is an essential and fundamental security service in mobile ad hoc networks (MANETs). It is needed to securely cope with dynamic membership and topology and to bootstrap other important security primitives (such as key management) and services (such as secure routing) without the assistance of any centralized trusted authority. An ideal admission protocol must involve minimal interaction among the MANET nodes, since connectivity can be unstable. Also, since MANETs are often composed of weak or resource-limited devices, admission control must be efficient in terms of computation and communication. Most previously proposed admission control protocols are prohibitively expensive and require a lot of interaction among MANET nodes in order to securely reach limited consensus regarding admission and cope with potentially powerful adversaries. While the expense may be justified for long-lived group settings, short-lived MANETs can benefit from much less expensive techniques without sacrificing any security. In this paper, we consider short-lived MANETs and present a secure, efficient and a fully non-interactive admission control protocol for such networks. More specifically, our work is focused on novel applications of non-interactive secret sharing techniques based on bi-variate polynomials, but, unlike other results, the associated costs are very low

Decentralized node admission is an essential and fundamental security service in mobile ad hoc networks (MANETs). It is needed to securely cope with dynamic membership and topology as well as to bootstrap other important security primitives (such as key management) and services (such as secure routing) without the assistance of any centralized trusted authority. An ideal admission technique must involve minimal interaction among MANET nodes, since connectivity can be unstable. Also, since MANETs are often composed of weak or resource-limited devices, admission must be efficient in terms of computation and communication. Most previously proposed admission protocols are prohibitively expensive and require heavy interaction among MANET nodes. In this paper, we focus on a common type of MANET that is formed on a temporary basis, and present a secure, efficient, and a fully noninteractive admission technique geared for this type of a network. Our admission protocol is based on secret sharing techniques using bivariate polynomials. We also present a new scheme that allows any pair of MANET nodes to efficiently establish an on-the-fly secure communication channel.