The evolution from 5G to 6G cellular networks signifies a crucial advancement towards enhanced robustness and automation driven by the promise of ubiquitous Artificial Intelligence (AI) to overhaul network operations, commonly referred to as AIOps. However, 6G network operators also need to deal with evolving threats at the edge to ensure data integrity and availability. We introduce 6G-XSEC, the first framework that seeks to automatically monitor, analyze, and explain anomalies and threats at the cellular network edge. Our framework enhances the emerging Open Radio Access Network (O-RAN) control plane with run-time analytic capabilities and explainability. A distinguishing aspect of our framework is the use of expert referencing, a coupling of lightweight unsupervised deep learning-based anomaly detection with large language models (LLMs) to first detect, analyze, and subsequently explain complicated real-world cellular threats and anomalies at run-time, based on enhanced security telemetry from the O-RAN data plane. We build a prototype 6G-XSEC framework and evaluate it against 5 end-to-end cellular attacks from the literature, achieving 100% detection rate with our best model. We also propose effective LLM prompt templates for attack analysis and present qualitative results from 5 popular LLMs.

We explore the application of Large Language Models (LLMs) (specifically GPT-3.5-turbo) to extract specifications and automating understanding of networking protocols from Internet Request for Comments (RFC) documents. LLMs have proven successful in specialized domains like medical and legal text understanding, and this work investigates their potential in automatically comprehending RFCs. We develop Artifact Miner, a tool to extract diagram artifacts from RFCs. We then couple extracted artifacts with natural language text to extract protocol automata using GPT-turbo 3.5 (chatGPT) and present our zero-shot and few-shot extraction results. We call this framework for FSM extraction 'PROSPER: Protocol Specification Miner'. We compare PROSPER with existing state-of-the-art techniques for protocol FSM state and transition extraction. Our experiments indicate that employing artifacts along with text for extraction can lead to lower false positives and better accuracy for both extracted states and transitions. Finally, we discuss efficient prompt engineering techniques, the errors we encountered, and pitfalls of using LLMs for knowledge extraction from specialized domains such as RFC documents.

The proliferation of global censorship has led to the development of a plethora of measurement platforms to monitor and expose it. Censorship of the domain name system (DNS) is a key mechanism used across different countries. It is currently detected by applying heuristics to samples of DNS queries and responses (probes) for specific destinations. These heuristics, however, are both platform-specific and have been found to be brittle when censors change their blocking behavior, necessitating a more reliable automated process for detecting censorship.

While the use of containerization technologies for virtual application deployment has grown at an astonishing rate, the question of the robustness of container networking has not been well scrutinized from a security perspective, even though inter-container networking is indispensable for microservices. Thus, this paper first analyzes container networks from a security perspective, discussing the implications based on their architectural limitations. Then, it presents Bastion+, a secure inter-container communication bridge. Bastion+ introduces ($i$) a network security enforcement stack that provides fine-grained control per container application and securely isolates inter- container traffic in a point-to-point manner. Bastion+ also supports ($ii$) selective security function chaining, enabling various security functions to be chained between containers for further security inspections (e.g., deep packet inspection) according to the container’s network context. Bastion+ incorporates ($iii$) a security policy assistant that helps an administrator discover inter-container networking dependencies correctly. Our evaluation demonstrates how Bastion+ can effectively mitigate several adversarial attacks in container networks while improving the overall performance up to 25.4% within single-host containers and 17.7% for cross-host container communications.

Multiple Perspective attack Investigation (MPI) is a technique to partition application dependencies based on high-level semantics. It facilitates provenance analysis by generating succinct causal graphs. It involves an annotation process that identifies variables and data structures corresponding to the partitions and the communication channels between them. Though the amount of annotation is small, this process requires a detailed understanding of the source code. In this work, autoMPI, we extend the capability ofMPIby automating the identifying annotation requirements. We leverage a hybrid analysis approach, performing a differential analysis based on crafted inputs. Static analysis is conducted to identify the annotation sites within the application code afterward automatically. Our evaluation shows the proposed approach can significantly facilitate the annotation process. It correctly identifies all required annotation sites within an average 16 seconds analysis time for the majority of analyzed programs with average precision and recall 72.5% and 100%, respectively.

Serverless computing has greatly simplified cloud programming. It liberates cloud tenants from various system administration and resource management tasks, such as configuration and provisioning. Under this new cloud computing paradigm, a single monolithic application is divided into separate stateless functions, i.e., function-as-a-service (FaaS), which are then orchestrated together to support complex business logic. But there is a fundamental cost associated with this enhanced flexibility. Internal network connections between functions are now initiated frequently, to support serverless features such as agile autoscaling and function chains, raising communication latency. To alleviate this cost, current serverless providers sacrifice security for performance, keeping internal function communications unencrypted.

Programmability is a double-edged sword. It can better tailor solutions to problems, optimize resource use, and inexpensively patch deployed equipment. But programmability can also be abused to undermine the security of hardware and that of its unwitting users. Remote Attestation (RA) is a class of techniques to provide integrity assurance to remote users of resources such as hardware, OSs and applications. It is used to establish well-defined trust relationships among mutually distrustful principals who provide, use or delegate remote resources. RA could benefit, for example, tenants of a data-center or users of IoT equipment such as health monitors.

The security of container-based microservices relies heavily on the isolation of operating system resources that is provided by namespaces. However, vulnerabilities exist in the isolation of containers that may be exploited by attackers to gain access to the host. These are commonly referred to as container escape attacks. While prior work has identified vulnerabilities in namespace isolation, no general container escape detection and warning system has been presented. We present Paced, a novel, realtime system to detect container-escape attacks. We define what constitutes a cross-namespace event and how such events can be used to detect a container escape attack. We develop a provenance-based approach to isolate cross-namespace events and propose a rule—privileged_flow—to detect attacks on Docker and Kubernetes environments. We evaluate our detection method on a suite of contemporary CVEs with container escape exploits, bad container configurations, and benchmarks. Paced achieves near-perfect accuracy with no false negatives. We release our implementation and datasets as free, open-source software.

Software-Defined Networking (SDN) has aggressively grown in data center networks, telecommunication providers, and enterprises by virtue of its programmable and extensible control plane. Also, there have been many kinds of research on the security of SDN components along with the growth of SDN. Some of them have inspected network policy inconsistency problems that can severely cause network reliability and security issues in SDN. However, they do not consider whether a single network policy itself is corrupted during processing inside and between SDN components. In this paper, we thus focus on the question of how to automatically identify cases in which the SDN stack fails to prevent policy inconsistencies from arising among those components. We then present AudiSDN, an automated fuzz-testing framework designed to formulate test cases in which policy inconsistencies can arise inOpenFlownetworks, the most prevalent SDN protocol. To prove its feasibility, we applied AudiSDN to two widely used SDN controllers, Floodlight and ONOS, and uncovered three separate CVEs (Common Vulnerabilities and Exposures) that cause the network policy inconsistencies among SDN components. Furthermore, we investigate the design flaws that cause the inconsistencies in modern SDN components, suggesting specific validations to address such a serious but understudied pragmatic concern.

In serverless computing [3], cloud providers manage responsibility for all server-related tasks, including both hardware resource allocation and software runtime preparation. Cloud tenants are thus free to simply focus on designing discrete stateless functions and orchestrate them together for their high-level business logic.

We present TRACE, a comprehensive provenance tracking system for scalable, real-time, enterprise-wide APT detection. TRACE uses static analysis to identify program unit structures and inter-unit dependences, such that the provenance of an output event includes the input events within the same unit. Provenance collected from individual hosts are integrated to facilitate construction of a distributed enterprise-wide causal graph. We describe the evolution of TRACE over a four-year period, during which our improvements to the system focused on performance, scalability, and fidelity. In this time span, the system call coverage increased (from 47 to 66) while the time and space overhead reduced by over one and two orders of magnitude, respectively. We also provide results from five adversarial engagements where an independent team of system evaluators conducted APT attacks and assessed system performance. The input from our system was used by three other teams to implement real-time APT detection logic. Retrospective analysis revealed that TRACE provided sufficient evidence to detect over 80% of the attack stages across all evaluations. By the last engagement, temporal and spatial overhead had been reduced significantly to 18% and 10%, respectively.

Textual data mining of open source intelligence on the Web has become an increasingly important topic across a wide range of domains such as business, law enforcement, military, and cybersecurity. Text mining efforts utilize natural language processing to transform unstructured web content into structured forms that can drive various machine learning applications and data indexing services. For example, applications for text mining in cybersecurity have produced a range of threat intelligence services that serve the IT industry. However, a less studied problem is that of automating the identification of semantic inconsistencies among various text input sources. In this paper, we introduce GapFinder, a new inconsistency checking system for identifying semantic inconsistencies within the cybersecurity domain. Specifically, we examine the problem of identifying technical inconsistencies that arise in the functional descriptions of open source malware threat reporting information. Our evaluation, using tens of thousands of relations derived from web-based malware threat reports, demonstrates the ability of GapFinder to identify the presence of inconsistencies.

The robustness of a network’s connectivity to other networks is often highly dependent on a few critical nodes and links that tie the network to the larger topology. The failure or degradation to such network bottlenecks can result in outages that may propagate throughout the network. Unfortunately, the presence of the bottlenecks also offers opportunities for targetedlink flooding attacks (LFAs). Researchers have proposed a new and promising defense to counter LFAs, referred to astopology deception. This strategy centers on hindering the discovery of bottlenecks by presenting false trace responses to adversaries as they perform topological probing of the target network. Even though the goal of topology deception centers on obscuring critical links, node dependencies can be exploited by an adversary. However, current approaches do not consider a wide range of metrics that may reveal important and diverse aspects of network bottlenecks. Furthermore, existing approaches create a simple form of virtual topology, which is subject to relatively easy detection by the adversary, reducing its effectiveness. In this paper, we propose a comprehensive topology deception framework, which we refer to as BottleNet. Our suggested approach can analyze various network topology features both with respect to static and dynamic metrics and then use this information to identify bottlenecks, finally producing complex virtual topologies that are resilient to adversarial detection.

At the foundation of every network security architecture lies the premise that formulated network flow policies are reliably deployed and enforced by the network infrastructure. However, software-defined networks (SDNs) add a particular challenge to satisfying this premise, as for SDNs the flow pol-icy implementation spans multiple applications and abstraction layers across the SDN stack. In this paper, we focus on the question of how to automatically identify cases in which the SDN stack fails to prevent policy inconsistencies from arising among these components. This question is rather essential, as when such inconsistencies arise the implications to the security and reliability of the network are devastating. We present AudiSDN, an automated fuzz-testing framework designed to formulate test cases in which policy inconsistencies can arise in OpenFlow networks, the most prevalent SDN protocol used today. We also present results from applying AudiSDN to two widely used SDN controllers, Floodlight and ONOS. In fact, our test results have led to the filing of 3 separate CVE reports. We believe that the approach presented in this paper is applicable to the breadth of OpenFlow platforms used today, and that its broader usage will help to address a serious but yet understudied pragmatic concern.

Consumer IoT networks are characterized by heterogeneous devices with diverse functionality and programming interfaces. This lack of homogeneity makes the integration and secure management of IoT infrastructures a daunting task for users and administrators. In this paper, we introduce VISCR, a Vendor-Independent policy Specification and Conflict Resolution engine that enables intent-based conflict-free policy specification and enforcement in IoT environments. VISCR converts the topology of the IoT infrastructure into a tree-based abstraction and translates existing policies from heterogeneous vendor-specific programming languages, such as Groovy-based SmartThings, OpenHAB, IFTTT-based templates, and MUD-based profiles, into a vendor-independent graph-based specification. These are then used to automatically detect rogue policies, policy conflicts, and automation bugs. We evaluated VISCR using a dataset of 907 IoT apps, programmed using heterogeneous automation specifications, in a simulated smart-building IoT infrastructure. In our experiments, among 907 IoT apps, VISCR exposed 342 of IoT apps as exhibiting one or more violations, while also running 14.2x faster than the state-of-the-art tool (Soteria). VISCR detected 100% of violations reported by Soteria while also detecting new types of violations in 266 additional apps.

An important consideration in software-defined networks (SDNs), is that one SDN application, through a bug or API misuse, can break an entire SDN. While previous works have tried to mitigate such concerns by implementing access control mechanisms (permission models) for an SDN controller, they commonly require serious manual efforts in creating a permission model. Moreover, they do not support flexible permission models, and they are often tightly coupled with a specific SDN controller. To address such limitations, we introduce an automated permission generation and verification system called VOGUE. A distinguishing aspect of VOGUE is that it automatically generates flexible permission models and yet is completely separated from the SDN controller implementation. To demonstrate the feasibility of our approach, we implement a prototype, evaluate its completeness and soundness, and examine its performance. In addition, to show the effectiveness of VOGUE, we demonstrate its use cases and security impact to SDN in the context of popular SDN controllers.

The Science DMZ (SDMZ) is a special purpose network architecture proposed by ESnet (Energy Sciences Network) to facilitate distributed science experimentation on terabyte- (or petabyte-) scale data, exchanged over ultra-high bandwidth WAN links. Critical security challenges faced by these networks include: (i) network monitoring at high bandwidths, (ii) reconciling site-specific policies with project-level policies for conflict-free policy enforcement, (iii) dealing with geographically-distributed datasets with varying levels of sensitivity, and (iv) dynamically enforcing appropriate security rules. To address these challenges, we develop a fine-grained dataflow-based security enforcement system, called CoordiNetZ (CNZ), that provides coordinated situational awareness, i.e., the use of context-aware tagging for policy enforcement using the dynamic contextual information derived from hosts and network elements. We also developed tag and IP-based security microservices that incur minimal overheads in enforcing security to data flows exchanged across geographically-distributed SDMZ sites. We evaluate our prototype implementation across two geographically distributed SDMZ sites with SDN-based case studies, and present performance measurements that respectively highlight the utility of our framework and demonstrate efficient implementation of security policies across distributed SDMZ networks.

Analysing software and networks can be done using established tools, such as debuggers and packet analysers, but using established tools to analyse network software is difficult and impractical because of the sheer detail the tools present and the performance overheads they typically impose. This makes it difficult to precisely diagnose performance anomalies in network software to identify their causes (is it a DoS attack or a bug?) and determine what needs to be fixed.We present Flowdar: a practical tool for analysing software traces to produce intuitive summaries of network software behaviour by abstracting unimportant details and demultiplexing traces into different sessions' subtraces. Flowdar can use existing state-of-the-art tracing tools for lower overhead during trace gathering for offline analysis. Using Flowdar we can drill down when diagnosing performance anomalies without getting overwhelmed in detail or burdening the system being observed.We show that Flowdar can be applied to existing real-world software and can digest complex behaviour into an intuitive visualisation.

Barista is a novel architecture that seeks to enable flexible and customizable instantiations of network operating systems (NOSs) for software-defined networks (SDNs). As the NOS is the strategic control center of an SDN, implementing logic for management of network switches as well as higher-level applications, its design is critical to the welfare of the network. In this paper, we focus on three aspects of composable controller design: component synthesis, dynamic event control, and predictive NOS assessment. First, the modular design of the Barista enables flexible composition of functionalities prevalent in contemporary SDN controllers. Second, its event handling mechanism enables dynamic customization of control flows in a NOS. Third, its predictive NOS assessment helps to discover the optimal composition for the requirements specified by operators. These capabilities allow Barista operators to optimally select functionalities and dynamically handle events for their operating requirements while maximizing the resource utilization of the given system. Our results demonstrate that Barista can synthesize NOSs with many functionalities found in commodity controllers with competitive performance profiles.

As the network operating system (NOS) is the strategic control center of a software-defined network (SDN), its design is critical to the welfare of the network. Contemporary research has largely focused on specialized NOSs that seek to optimize controller design across one or a few dimensions (e.g., scalability, performance, or security) due to fundamental differences in architectural trade-offs needed to support competing demands. We thus designed Barista, as a new framework that enables flexible and customizable instantiations of network operating systems (NOSs) supporting diverse design choices. The Barista framework incorporates two mechanisms to harmonize architectural differences across design choices: component synthesis and dynamic event control. First, the modular design of the Barista framework enables flexible composition of functionalities prevalent in contemporary SDN controllers. Second, its event-handling mechanism enables dynamic adjustment of control flows in a NOS. These capabilities allow operators to easily enable functionalities and dynamically handle associated events, thereby satisfying network operating requirements. Our results demonstrate that Barista can synthesize NOSs with many functionalities found in commodity NOSs with competitive performance profiles.

Management approaches to modern networks are increasingly influenced by software-defined networks (SDNs), and this increased influence is reflected in the growth of commercially available innovative SDN-based switches, controllers and applications. To date, there have been a number of commercial and open-source SDN operating systems (NOS) introduced for various purposes, including distributed controller frameworks targeting large, carrier-grade networks such as the Open Network Operating System (ONOS) and OpenDayLight (ODL). These frameworks are distinguished by their (i) elastic cluster controller architecture, (ii) network virtualization support, and (iii) modular design. Given their flexible design, growing list of supported features, and collaborative community support, these are attractive hosting platforms for a wide range of third-party distributed network management applications. This paper identifies the common security requirements for policy enforcement in such distributed controller environments. We present the design of a network application permission-enforcement model and an integrated security subsystem (SM-ONOS) for managing distributed applications running on an ONOS controller. We discuss the underlying motivations of its security extensions and their implications for improving our understanding of how to securely manage large-scale SDNs. Our performance assessments demonstrate that the security-mode extension imposed reasonable overheads (ranging from 5 to 20% for 1-7 node clusters).

We design Barista, as a new framework that seeks to enable flexible and customizable instantiations of network operating systems (NOSs) supporting diverse design choices, using two key features that harmonize architectural differences across design choices: component synthesis and dynamic event control. With these capabilities, Barista operators to easily enable functionalities and dynamically adjust the control flows among those functionalities.

Network-based anomaly detection is a well-mined area of research, with many projects that have produced algorithms to detect suspicious and anomalous activities at strategic points in a network. In this paper, we examine how to integrate an anomaly detection development framework into existing software-defined network (SDN) infrastructures to support sophisticated anomaly detection services across the entire network data plane, not just at network egress boundaries. We present Athena as a new SDN-based software solution that exports a well-structured development interface and provides general purpose functions for rapidly synthesizing a wide range of anomaly detection services and network monitoring functions with minimal programming effort. Athena is a fully distributed application hosting architecture, enabling a unique degree of scalability from prior SDN security monitoring and analysis projects. We discuss example use-case scenarios with Athena's development libraries, and evaluate system performance with respect to usability, scalability, and overhead in real world environments.

The Science DMZ (SDMZ) is a special purpose network infrastructure that is engineered to cater to the ultra-high bandwidth needs of the scientific and high performance computing (HPC) communities. These networks are isolated from stateful security devices such as firewalls and deep packet inspection (DPI) engines to allow HPC data transfer nodes (DTNs) to efficiently transfer petabytes of data without associated bandwidth and performance bottlenecks. This paper presents our ongoing effort toward the development of more fine-grained data flow access control policies to manage SDMZ networks that service large-scale experiments with varying data sensitivity levels and privacy constraints.

Onion sites on the darkweb operate using the Tor Hidden Service (HS) protocol to shield their locations on the Internet, which (among other features) enables these sites to host malicious and illegal content while being resistant to legal action and seizure. Identifying and monitoring such illicit sites in the darkweb is of high relevance to the Computer Security and Law Enforcement communities. We have developed an automated infrastructure that crawls and indexes content from onion sites into a large-scale data repository, called LIGHTS, with over 100M pages. In this paper we describe Automated Tool for Onion Labeling (ATOL), a novel scalable analysis service developed to conduct a thematic assessment of the content of onion sites in the LIGHTS repository. ATOL has three core components -- (a) a novel keyword discovery mechanism (ATOLKeyword) which extends analyst-provided keywords for different categories by suggesting new descriptive and discriminative keywords that are relevant for the categories; (b) a classification framework (ATOLClassify) that uses the discovered keywords to map onion site content to a set of categories when sufficient labeled data is available; (c) a clustering framework (ATOLCluster) that can leverage information from multiple external heterogeneous knowledge sources, ranging from domain expertise to Bitcoin transaction data, to categorize onion content in the absence of sufficient supervised data. The paper presents empirical results of ATOL on onion datasets derived from the LIGHTS repository, and additionally benchmarks ATOL's algorithms on the publicly available 20 Newsgroups dataset to demonstrate the reproducibility of its results. On the LIGHTS dataset, ATOLClassify gives a 12% performance gain over an analyst-provided baseline, while ATOLCluster gives a 7% improvement over state-of-the-art semi-supervised clustering algorithms. We also discuss how ATOL has been deployed and externally evaluated, as part of the LIGHTS system.

Emerging software defined network (SDN) stacks have introduced an entirely new attack surface that is exploitable from a wide range of launch points. Through an analysis of the various attack strategies reported in prior work, and through our own efforts to enumerate new and variant attack strategies, we have gained two insights. First, we observe that different SDN controller implementations, developed independently by different groups, seem to manifest common sets of pitfalls and design weakness that enable the extensive set of attacks compiled in this paper. Second, through a principled exploration of the underlying design and implementation weaknesses that enables these attacks, we introduce a taxonomy to offer insight into the common pitfalls that enable SDN stacks to be broken or destabilized when fielded within hostile computing environments. This paper first captures our understanding of the SDN attack surface through a comprehensive survey of existing SDN attack studies, which we extend by enumerating 12 new vectors for SDN abuse. We then organize these vulnerabilities within the well-known confidentiality, integrity, and availability model, assess the severity of these attacks by replicating them in a physical SDN testbed, and evaluate them against three popular SDN controllers. We also evaluate the impact of these attacks against published SDN defense solutions. Finally, we abstract our findings to offer the research and development communities with a deeper understanding of the common design and implementation pitfalls that are enabling the abuse of SDN networks.

The performance and operational characteristics of the Domain Name System (DNS) protocol are of deep interest to the research and network operations community. In this paper, we present measurement results from a unique dataset containing more than 26 billion DNS query-response pairs collected from more than 600 globally distributed recursive DNS resolvers. We use this dataset to reaffirm findings in published work and notice some significant differences that could be attributed both to the evolving nature of DNS traffic and to our differing perspective. For example, we find that although characteristics of DNS traffic vary greatly across networks, the resolvers within an organization tend to exhibit similar behavior. We further find that more than 50% of DNS queries issued to root servers do not return successful answers, and that the primary cause of lookup failures at root servers is malformed queries with invalid top-level domains (TLDs). Furthermore, we propose a novel approach that detects malicious domain groups using temporal correlation in DNS queries. Our approach requires no comprehensive labeled training set, which can be difficult to build in practice. Instead, it uses a known malicious domain as anchor and identifies the set of previously unknown malicious domains that are related to the anchor domain. Experimental results illustrate the viability of this approach, i.e., we attain a true positive rate of more than 96%, and each malicious anchor domain results in a malware domain group with more than 53 previously unknown malicious domains on average.

Within the hierarchy of the Software Defined Network (SDN) network stack, the control layer operates as the critical middleware facilitator of interactions between the data plane and the network applications, which govern flow routing decisions. In the OpenFlow implementation of the SDN model, the control layer, commonly referred to as a network operating system (NOS), has been realized by a range of competing implementations that offer various performance and functionality advantages: Floodlight, POX, NOX, and ONIX. In this paper we focus on the question of control layer resilience, when rapidly developed prototype network applications go awry, or third-party network applications incorporate unexpected vulnerabilities, fatal instabilities, or even malicious logic. We demonstrate how simple and common failures in a network application may lead to loss of the control layer, and in effect, loss of network control. To address these concerns we present the ROSEMARY controller, which implements a network application containment and resilience strategy based around the notion of spawning applications independently within a micro-NOS. ROSEMARY distinguishes itself by its blend of process containment, resource utilization monitoring, and an application permission structure, all designed to prevent common failures of network applications from halting operation of the SDN Stack. We present our design and implementation of ROSEMARY, along with an extensive evaluation of its performance relative to several of the mostly well-known and widely used controllers. Rather than imposing significant performance costs, we find that with the integration of two optimization features, ROSEMARY offers a competitive performance advantage over the majority of other controllers.

Among the leading reference implementations of the Software Defined Networking (SDN) paradigm is the OpenFlow framework, which decouples the control plane into a centralized application. In this paper, we consider two aspects of OpenFlow that pose security challenges, and we propose two solutions that could address these concerns. The first challenge is the inherent communication bottleneck that arises between the data plane and the control plane, which an adversary could exploit by mounting a "control plane saturation attack" that disrupts network operations. Indeed, even well-mined adversarial models, such as scanning or denial-of-service (DoS) activity, can produce more potent impacts on OpenFlow networks than traditional networks. To address this challenge, we introduce an extension to the OpenFlow data plane called "connection migration", which dramatically reduces the amount of data-to-control-plane interactions that arise during such attacks. The second challenge is that of enabling the control plane to expedite both detection of, and responses to, the changing flow dynamics within the data plane. For this, we introduce "actuating triggers" over the data plane's existing statistics collection services. These triggers are inserted by control layer applications to both register for asynchronous call backs, and insert conditional flow rules that are only activated when a trigger condition is detected within the data plane's statistics module. We present Avant-Guard, an implementation of our two data plane extensions, evaluate the performance impact, and examine its use for developing more scalable and resilient SDN security services.

The OpenFlow (OF) switching specification represents an innovative and open standard for enabling the dynamic programming of flow control policies in production networks. Unfortunately, thus far researchers have paid little attention to the development of methods for verifying that dynamic flow policies inserted within an OpenFlow network do not violate the network's underlying security policy. We introduce Flover, a model checking system which verifies that the aggregate of flow policies instantiated within an OpenFlow network does not violate the network's security policy. We have implemented Flover using the Yices SMT solver, which we then integrated into NOX, a popular OpenFlow network controller. Flover provides NOX a formal validation of the OpenFlow network's security posture.

The performance and operational characteristics of the DNS protocol are of deep interest to the research and network operations community. In this paper, we present measurement results from a unique dataset containing more than 26 billion DNS query-response pairs collected from more than 600 globally distributed recursive DNS resolvers. We use this dataset to reaffirm findings in published work and notice some significant differences that could be attributed both to the evolving nature of DNS traffic and to our differing perspective. For example, we find that although characteristics of DNS traffic vary greatly across networks, the resolvers within an organization tend to exhibit similar behavior. We further find that more than 50% of DNS queries issued to root servers do not return successful answers, and that the primary cause of lookup failures at root servers is malformed queries with invalid TLDs. Furthermore, we propose a novel approach that detects malicious domain groups using temporal correlation in DNS queries. Our approach requires no comprehensive labeled training set, which can be difficult to build in practice. Instead, it uses a known malicious domain as anchor, and identifies the set of previously unknown malicious domains that are related to the anchor domain. Experimental results illustrate the viability of this approach, i.e. , we attain a true positive rate of more than 96%, and each malicious anchor domain results in a malware domain group with more than 53 previously unknown malicious domains on average.

Internet censorship by governments is an increasingly common practice worldwide. Internet users and censors are locked in an arms race: as users find ways to evade censorship schemes, the censors develop countermeasures for the evasion tactics. One of the most popular and effective circumvention tools, Tor, must regularly adjust its network traffic signature to remain usable.

The prevalence of malware in Android marketplaces is a growing and significant problem. Among the most worrisome concerns are with regarding to malicious Android applications that attempt to steal money from unsuspecting users. These malicious applications get uploaded under the guise of benign applications, typically to third-party alternative market places that lack proper security vetting procedures, and are subsequently downloaded and executed by unsuspecting victims. In this work, we propose "Money-Guard", a systematic approach to detect stealthy moneystealing applications in popular Android markets. Our technique relies on detecting two key behavioral heuristics that seem to be common across many money-stealing Android malware: hardcoded exfiltration and notification suppression. In our preliminary analysis of 47 SMS-based money stealing applications, we confirm that 41 of these applications follow the above pattern, and describe a light weight detection approach that will identify this behavioral pattern.

Web-based surreptitious malware infections (i.e., drive-by downloads) have become the primary method used to deliver malicious software onto computers across the Internet. To address this threat, we present a browser independent operating system kernel extension designed to eliminate driveby malware installations. The BLADE (Block All Drive-by download Exploits) system asserts that all executable files delivered through browser downloads must result from explicit user consent and transparently redirects every unconsented browser download into a nonexecutable secure zone of disk. BLADE thwarts the ability of browser-based exploits to surreptitiously download and execute malicious content by remapping to the file system only those browser downloads to which a programmatically inferred user-consent is correlated, BLADE provides its protection without explicit knowledge of any exploits and is thus resilient against code obfuscation and zero-day threats that directly contribute to the pervasiveness of today's drive-by malware. We present the design of our BLADE prototype implementation for the Microsoft Windows platform, and report results from as extensive empirical evaluation of its effectiveness on popular browsers. Our evaluation includes multiple versions of IE and Firefox, against 1,934 active malicious URLs, representing a broad spectrum of web-based exploits not plaguing the Internet. BLADE successfully blocked all drive-by malware install attempts with zero false positives and a 3% worst-case performance cost.

We consider the problem of identifying obscure chat-like botnet command and control (C & C) communications, which are indistinguishable from human-human communication using traditional signature-based techniques. Existing passive-behavior-based anomaly detection techniques are limited because they either require monitoring multiple bot-infected machines that belong to the same botnet or require extended monitoring times. In this paper, we explore the potential use of active botnet probing techniques in a network middle-box as a means to augment and complement existing passive botnet C & C detection strategies, especially for small botnets with obfuscated C & C content and infrequent C & C interactions. We present an algorithmic framework that uses hypothesis testing to separate botnet C & C dialogs from human-human conversations with desired accuracy and implement a prototype system called BotProbe. Experimental results on multiple real-world IRC bots demonstrate that our proposed active methods can successfully identify obscure and obfuscated botnet communications. A real-world user study on about one hundred participants also shows that the technique has a low false positive rate on human-human conversations. We discuss the limitations of BotProbe and hope this preliminary feasibility study on the use of active techniques in botnet research can inspire new thoughts and directions within the malware research community.

Traffic volume and diversity can have a significant impact on the ability of network intrusion detection systems (NIDS) to report malicious activity accurately. Based on the observation that a great deal of traffic is, in fact, not important to accurate attack identification, we investigate connection filtering as a method for improving the performance of NIDS. We describe three different classes of connection filters that were developed to explore the design space and trade off's in load reduction versus alarm rates. We implement instances of each filter class on a network processor that can be used with any NIDS that runs on commodity hardware, and evaluate the impact of each filter in a series of laboratory-based tests. First, we establish an idealized maximum performance by using static connection filters for all benign traffic. Next, we show that volume sensitive random connection filters can improve performance significantly with respect to alarm rates under heavy traffic load. Finally, we show that dynamic connection filters that attempt to infer benign traffic can improve performance almost to the level of idealized static filters. These results underscore the potential for hardware-based connection filtering as an effective means for improving the performance of NIDS.

Monitoring any portion of the Internet address space reveals incessant activity. This holds even when monitoring traffic sent to unused addresses, which we term "background radiation. " Background radiation reflects fundamentally nonproductive traffic, either malicious (flooding backscatter, scans for vulnerabilities, worms) or benign (misconfigurations). While the general presence of background radiation is well known to the network operator community, its nature has yet to be broadly characterized. We develop such a characterization based on data collected from four unused networks in the Internet. Two key elements of our methodology are (i) the use of filtering to reduce load on the measurement system, and (ii) the use of active responders to elicit further activity from scanners in order to differentiate different types of background radiation. We break down the components of background radiation by protocol, application, and often specific exploit; analyze temporal patterns and correlated activity; and assess variations across different networks and over time. While we find a menagerie of activity, probes from worms and autorooters heavily dominate. We conclude with considerations of how to incorporate our characterizations into monitoring and detection activities.

Malicious traffic from self-propagating worms and denial-of-service attacks constantly threatens the everyday operation of Internet systems. Defending networks from these threats demands appropriate tools to conduct comprehensive vulnerability assessments of networked systems. This paper describes MACE, a unique environment for recreating a wide range of malicious packet traffic in laboratory testbeds. MACE defines a model for flexible composition of malicious traffic that enables both known attacks (such as the Welchia worm) and new attack variants to be created. We implement this model in an extensible library for attack traffic specification and generation. To demonstrate the capability of MACE, we provide an analysis of stress tests conducted on a popular firewall and two popular network intrusion detection systems. Our results expose potential weaknesses of these systems and reveal that modern firewalls and network intrusion detection systems could be easily overwhelmed by simple attacks launched from a small number of hosts.

Network intrusions have been a fact of life in the Internet for many years. However, as is the case with many other types of Internet-wide phenomena, gaining insight into the global characteristics of intrusions is challenging. In this paper we address this problem by systematically analyzing a set of firewall logs collected over four months from over 1600 different networks world wide. The first part of our study is a general analysis focused on the issues of distribution, categorization and prevalence of intrusions. Our data shows both a large quantity and wide variety of intrusion attempts on a daily basis. We also find that worms like CodeRed, Nimda and SQL Snake persist long after their original release. By projecting intrusion activity as seen in our data sets to the entire Internet we determine that there are typically on the order of 25B intrusion attempts per day and that there is an increasing trend over our measurement period. We further find that sources of intrusions are uniformly spread across the Autonomous System space. However, deeper investigation reveals that a very small collection of sources are responsible for a significant fraction of intrusion attempts in any given month and their on/off patterns exhibit cliques of correlated behavior. We show that the distribution of source IP addresses of the non-worm intrusions as a function of the number of attempts follows Zipf's law. We also find that at daily timescales, intrusion targets often depict significant spatial trends that blur patterns observed from individual "IP telescopes"; this underscores the necessity for a more global approach to intrusion detection. Finally, we investigate the benefits of shared information, and the potential for using this as a foundation for an automated, global intrusion detection framework that would identify and isolate intrusions with greater precision and robustness than systems with limited perspective.