Botnets IRC et P2P pour une supervision à large échelle

National audienceAlors que le nombre d'équipements à superviser ne cesse de croître, le passage à l'échelle de la supervision des réseaux et services est un véritable enjeu. Un tel challenge semble avoir été par le passé surmonté par les botnets connus actuellement pour être une des principales menaces sur internet car un attaquant peut contrôler des milliers de machines. D'un point de vue technique, il serait très utile de les utiliser dans le cadre de la supervision des réseaux. Cet article propose une nouvelle solution de supervision basée sur les botnets et évalue les performances associées de manière à établir un comparatif détaillé des différents types de botnets utilisables pour la supervision

Deep Graph Embedding for IoT Botnet Traffic Detection

Botnet attacks have mainly targeted computers in the past, which is a fundamental cybersecurity problem. Due to the booming of Internet of things (IoT) devices, an increasing number of botnet attacks are now targeting IoT devices. Researchers have proposed several mechanisms to avoid botnet attacks, such as identification by communication patterns or network topology and defence by DNS blacklisting. A popular direction for botnet detection currently relies on the specific topological characteristics of botnets and uses machine learning models. However, it relies on network experts’ domain knowledge for feature engineering. Recently, neural networks have shown the capability of representation learning. This paper proposes a new approach to extracting graph features via graph neural networks. To capture the particular topology of the botnet, we transform the network traffic into graphs and train a graph neural network to extract features. In our evaluations, we use graph embedding features to train six machine learning models and compare them with the performance of traditional graph features in identifying botnet nodes. The experimental results show that botnet traffic detection is still challenging even with neural networks. We should consider the impact of data, features, and algorithms for an accurate and robust solution

Adversarial behaviours knowledge area

The technological advancements witnessed by our society in recent decades have brought improvements in our quality of life, but they have also created a number of opportunities for attackers to cause harm. Before the Internet revolution, most crime and malicious activity generally required a victim and a perpetrator to come into physical contact, and this limited the reach that malicious parties had. Technology has removed the need for physical contact to perform many types of crime, and now attackers can reach victims anywhere in the world, as long as they are connected to the Internet. This has revolutionised the characteristics of crime and warfare, allowing operations that would not have been possible before. In this document, we provide an overview of the malicious operations that are happening on the Internet today. We first provide a taxonomy of malicious activities based on the attacker’s motivations and capabilities, and then move on to the technological and human elements that adversaries require to run a successful operation. We then discuss a number of frameworks that have been proposed to model malicious operations. Since adversarial behaviours are not a purely technical topic, we draw from research in a number of fields (computer science, criminology, war studies). While doing this, we discuss how these frameworks can be used by researchers and practitioners to develop effective mitigations against malicious online operations.Published versio

Analysis of Malware and Domain Name System Traffic

Malicious domains host Command and Control servers that are used to instruct infected machines to perpetuate malicious activities such as sending spam, stealing credentials, and launching denial of service attacks. Both static and dynamic analysis of malware as well as monitoring Domain Name System (DNS) traffic provide valuable insight into such malicious activities and help security experts detect and protect against many cyber attacks. Advanced crimeware toolkits were responsible for many recent cyber attacks. In order to understand the inner workings of such toolkits, we present a detailed reverse engineering analysis of the Zeus crimeware toolkit to unveil its underlying architecture and enable its mitigation. Our analysis allows us to provide a breakdown for the structure of the Zeus botnet network messages. In the second part of this work, we develop a framework for analyzing dynamic analysis reports of malware samples. This framework can be used to extract valuable cyber intelligence from the analyzed malware. The obtained intelligence helps reveal more insight into different cyber attacks and uncovers abused domains as well as malicious infrastructure networks. Based on this framework, we develop a severity ranking system for domain names. The system leverages the interaction between domain names and malware samples to extract indicators for malicious behaviors or abuse actions. The system utilizes these behavioral features on a daily basis to produce severity or abuse scores for domain names. Since our system assigns maliciousness scores that describe the level of abuse for each analyzed domain name, it can be considered as a complementary component to existing (binary) reputation systems, which produce long lists with no priorities. We also developed a severity system for name servers based on passive DNS traffic. The system leverages the domain names that reside under the authority of name servers to extract indicators for malicious behaviors or abuse actions. It also utilizes these behavioral features on a daily basis to dynamically produce severity or abuse scores for name servers. Finally, we present a system to characterize and detect the payload distribution channels within passive DNS traffic. Our system observes the DNS zone activities of access counts of each resource record type and determines payload distribution channels. Our experiments on near real-time passive DNS traffic demonstrate that our system can detect several resilient malicious payload distribution channels

Tracking and Mitigation of Malicious Remote Control Networks

Attacks against end-users are one of the negative side effects of today’s networks. The goal of the attacker is to compromise the victim’s machine and obtain control over it. This machine is then used to carry out denial-of-service attacks, to send out spam mails, or for other nefarious purposes. From an attacker’s point of view, this kind of attack is even more efficient if she manages to compromise a large number of machines in parallel. In order to control all these machines, she establishes a "malicious remote control network", i.e., a mechanism that enables an attacker the control over a large number of compromised machines for illicit activities. The most common type of these networks observed so far are so called "botnets". Since these networks are one of the main factors behind current abuses on the Internet, we need to find novel approaches to stop them in an automated and efficient way. In this thesis we focus on this open problem and propose a general root cause methodology to stop malicious remote control networks. The basic idea of our method consists of three steps. In the first step, we use "honeypots" to collect information. A honeypot is an information system resource whose value lies in unauthorized or illicit use of that resource. This technique enables us to study current attacks on the Internet and we can for example capture samples of autonomous spreading malware ("malicious software") in an automated way. We analyze the collected data to extract information about the remote control mechanism in an automated fashion. For example, we utilize an automated binary analysis tool to find the Command & Control (C&C) server that is used to send commands to the infected machines. In the second step, we use the extracted information to infiltrate the malicious remote control networks. This can for example be implemented by impersonating as a bot and infiltrating the remote control channel. Finally, in the third step we use the information collected during the infiltration phase to mitigate the network, e.g., by shutting down the remote control channel such that the attacker cannot send commands to the compromised machines. In this thesis we show the practical feasibility of this method. We examine different kinds of malicious remote control networks and discuss how we can track all of them in an automated way. As a first example, we study botnets that use a central C&C server: We illustrate how the three steps can be implemented in practice and present empirical measurement results obtained on the Internet. Second, we investigate botnets that use a peer-to-peer based communication channel. Mitigating these botnets is harder since no central C&C server exists which could be taken offline. Nevertheless, our methodology can also be applied to this kind of networks and we present empirical measurement results substantiating our method. Third, we study fast-flux service networks. The idea behind these networks is that the attacker does not directly abuse the compromised machines, but uses them to establish a proxy network on top of these machines to enable a robust hosting infrastructure. Our method can be applied to this novel kind of malicious remote control networks and we present empirical results supporting this claim. We anticipate that the methodology proposed in this thesis can also be used to track and mitigate other kinds of malicious remote control networks

Mitigating Botnet-based DDoS Attacks against Web Servers

Distributed denial-of-service (DDoS) attacks have become wide-spread on the Internet. They continuously target retail merchants, financial companies and government institutions, disrupting the availability of their online resources and causing millions of dollars of financial losses. Software vulnerabilities and proliferation of malware have helped create a class of application-level DDoS attacks using networks of compromised hosts (botnets). In a botnet-based DDoS attack, an attacker orders large numbers of bots to send seemingly regular HTTP and HTTPS requests to a web server, so as to deplete the server's CPU, disk, or memory capacity. Researchers have proposed client authentication mechanisms, such as CAPTCHA puzzles, to distinguish bot traffic from legitimate client activity and discard bot-originated packets. However, CAPTCHA authentication is vulnerable to denial-of-service and artificial intelligence attacks. This dissertation proposes that clients instead use hardware tokens to authenticate in a federated authentication environment. The federated authentication solution must resist both man-in-the-middle and denial-of-service attacks. The proposed system architecture uses the Kerberos protocol to satisfy both requirements. This work proposes novel extensions to Kerberos to make it more suitable for generic web authentication. A server could verify client credentials and blacklist repeated offenders. Traffic from blacklisted clients, however, still traverses the server's network stack and consumes server resources. This work proposes Sentinel, a dedicated front-end network device that intercepts server-bound traffic, verifies authentication credentials and filters blacklisted traffic before it reaches the server. Using a front-end device also allows transparently deploying hardware acceleration using network co-processors. Network co-processors can discard blacklisted traffic at the hardware level before it wastes front-end host resources. We implement the proposed system architecture by integrating existing software applications and libraries. We validate the system implementation by evaluating its performance under DDoS attacks consisting of floods of HTTP and HTTPS requests

Using Malware Analysis to Evaluate Botnet Resilience

Bos, H.J. [Promotor]Steen, M.R. van [Promotor

Robust Botnet Detection Techniques for Mobile and Network Environments

Cybercrime costs large amounts of money and resources every year. This is because it is usually carried out using different methods and at different scales. The use of botnets is one of the most common successful cybercrime methods. A botnet is a group of devices that are used together to carry out malicious attacks (they are connected via a network). With the widespread usage of handheld devices such as smartphones and tablets, networked devices are no longer limited to personal computers and laptops. Therefore, the size of networks (and therefore botnets) can be large. This means it is not surprising for malicious users to target different types of devices and platforms as cyber-attack victims or use them to launch cyber-attacks. Thus, robust automatic methods of botnet detection on different platforms are required. This thesis addresses this problem by introducing robust methods for botnet family detection on Android devices as well as by generally analysing network traffic. As for botnet detection on Android, this thesis proposes an approach to identify botnet Android botnet apps by means of source code mining. The approach analyses the source code via reverse engineering and data mining techniques for several examples of malicious and non-malicious apps. Two methods are used to build datasets. In the first, text mining is performed on the source code and several datasets are constructed, and in the second, one dataset is created by extracting source code metrics using an open-source tool. Additionally, this thesis introduces a novel transfer learning approach for the detection of botnet families by means of network traffic analysis. This approach is a key contribution to knowledge because it adds insight into how similar instances can exist in datasets that belong to different botnet families and that these instances can be leveraged to enhance model quality (especially for botnet families with small datasets). This novel approach is denoted Similarity Based Instance Transfer, or SBIT. Furthermore, the thesis presents a proposed extended version designed to overcome a weakness in the original algorithm. The extended version is called CB-SBIT (Class Balanced Similarity Based Instance Transfer)

Web usage mining for click fraud detection

Estágio realizado na AuditMark e orientado pelo Eng.º Pedro FortunaTese de mestrado integrado. Engenharia Informática e Computação. Faculdade de Engenharia. Universidade do Porto. 201