Dynamic Defense against Adaptive and Persistent Adversaries

Advanced persistent threats (APTs) consist of multiple attack stages between entry and exit points of the attack. In each stage of the attack, the adversary gathers more privileges, resources, and information about the system and uses this information to gain access to the targeted data of the next stage to reach the final goal. APTs are not only persistent but also stealthy and hence difficult to detect. The persistent nature of APTs, however, creates information flows in the system that can be monitored. One monitoring mechanism is Dynamic Information Flow Tracking (DIFT), which taints and tracks malicious information flows through a system and inspects the flows at designated traps. Since tainting all flows in the system will incur prohibitive resource costs, efficient tagging policies are needed to decide which flows to tag in order to maximize the probability of APT detection while minimizing resource overhead. At present such an analytical model for DIFT for multi-stage APT detection does not exist. In this paper, we propose a game theoretic framework modeling real-time detection of multi-stage APTs via DIFT. We formulate a two-player (APT vs DIFT) nonzero-sum stochastic game with incomplete information to obtain an optimal tagging policy. Our game model consists of a sequence of stages, where each stage of the game corresponds to a stage in the attack. At each stage, the goal of the APT is to reach a particular destination, corresponding to a targeted resource or privilege, while the goal of the defender is to detect the APT. We first derive an efficient algorithm to find locally optimal strategies for both players. We then characterize the best responses of both players and present algorithms to find the best responses. Finally, we validate our results on a real-world attack data set obtained using the Refinable Attack INvestigation (RAIN) framework for a ScreenGrab attack.

Advanced Persistent Threats (APTs) are stealthy, sophisticated, long-term, multi-stage attacks that threaten the security of sensitive information. Dynamic Information Flow Tracking (DIFT) has been proposed as a promising mechanism to detect and prevent various cyber attacks in computer systems. DIFT tracks suspicious information flows in the system and generates security analysis when anomalous behavior is detected. The number of information flows in a system is typically large and the amount of resources (such as memory, processing power and storage) required for analyzing different flows at different system locations varies. Hence, efficient use of resources is essential to maintain an acceptable level of system performance when using DIFT. On the other hand, the quickest detection of APTs is crucial as APTs are persistent and the damage caused to the system is more when the attacker spends more time in the system. We address the problem of detecting APTs and model the trade-off between resource efficiency and quickest detection of APTs. We propose a game model that captures the interaction of APT and a DIFT-based defender as a two-player, multi-stage, zero-sum, Stackelberg semi-Markov game. Our game considers the performance parameters such as false-negatives generated by DIFT and the time required for executing various operations in the system. We propose a two-time scale Q-learning algorithm that converges to a Stackelberg equilibrium under infinite horizon, limiting average payoff criteria. We validate our model and algorithm on a real-word attack dataset obtained using Refinable Attack INvestigation (RAIN) framework.

Cyberspace has been threatened by attacks ever since its birth. With the development of the information technologies, especially big data and artificial intelligence, many kinds of cyber attacks are emerging every day, causing severe consequences to society. Meanwhile, intelligent defense methods are proposed to detect these attacks. Such attack and defense methods are constantly being renovated. In particular, advanced persistent threats are intensifying. How to effectively prevent this type of attack has become the a vital problem in recent years. The detection and defense technologies have made great progress. This chapter mainly discusses the research progress of APT attack detection and defense strategies at home and abroad, and focuses on the practice of using machine learning methods to perform attack detection while elaborating on traditional attack detection methods. We also introduce game theory based defense strategy to find the best defense strategy in limited resources, dynamic information flow tracking and cloud platform. With the development of knowledge representation, how to use the MDATA model to characterize the APT attacks is also be discussed in this chapter.KeywordsMDATACyber securityAPT attackCyber defense

DIFT (Dynamic Information Flow Tracking) has been a hot topic for more than a decade. Unfortunately, existing hardware DIFT approaches have not been widely used neither by research community nor by hardware vendors. It is due to two major reasons: current hardware DIFT solutions lack support for multithreaded applications and implementations for hardcore processors. This work addresses both issues by introducing an approach with some unique features: DIFT for multi-threaded software, virtual memory protection (rather than physical memory as in related works) and Linux kernel support using an information flow monitor called RFBlare. These goals are accomplished by taking advantage of a notable feature of ARM CoreSight components (context ID) combined with a custom DIFT coprocessor and RFBlare. The communication time overhead, major source of slowdown in total DIFT time overhead, is divided by a factor 3.8 compared to existing solutions with similar software constraints as in this work. The area overhead of this work is lower than 1% and power overhead is 16.2% on a middle-class Xilinx Zynq SoC.

Dynamic Information Flow Tracking has been successfully used to prevent a wide range of attacks and detect illegal access to sensitive information. Most proposed solutions only track the explicit information flow where the taint is propagated through data dependencies. However, recent evasion attacks exploit implicit flows, that use control flow in the application, to manipulate the data thus making the malicious activity undetectable. We propose NIFT - a nested implicit flow tracking mechanism that extends explicit propagation to instructions affected by a control dependency. Our technique generates taint instructions at compile time which are executed by specialized hardware to propagate taint implicitly even in cases of deeply-nested branches. In addition, we propose a restricted taint propagation for data executed in conditional branches that affects only immediate instructions instead of all instructions inside the branch scope. Our technique efficiently locates implicit flows and resolves them with negligible performance overhead. Moreover, it mitigates the over-tainting problem.

In this paper, we describe for the first time, how Dynamic Information Flow Tracking (DIFT) can be implemented for heterogeneous designs that contain one or more on-chip accelerators attached to a network-on-chip. We observe that implementing DIFT for such systems requires holistic platform level view, i.e., designing individual components in the heterogeneous system to be capable of supporting DIFT is necessary but not sufficient to correctly implement full-system DIFT. Based on this observation we present a new system architecture for implementing DIFT, and also describe wrappers that provide DIFT functionality for third-party IP components. Results show that our implementation minimally impacts performance of programs that do not utilize DIFT, and the price of security is constant for modest amounts of tagging and then sub-linearly increases with the amount of tagging.

Security in embedded systems remains a major concern. Untrustworthy authorities use a wide range of software attacks. This demo introduces ARMHEx, a practical solution targeting DIFT (Dynamic Information Flow Tracking) implementations on ARM-based SoCs. DIFT is a solution that consists in tracking the dissemination of data inside the system and allows to enforce some security properties. In this demo, we show an implementation of ARMHEx on Xilinx Zynq SoC. Especially, we show how the required information for DIFT is recovered with the help of traces produced by CoreSight components, static analysis and instrumentation.

Security is a major issue nowadays for the embedded systems community. Untrustworthy authorities may use a wide range of attacks in order to retrieve critical information. This paper introduces ARMHEx, a practical solution targeting DIFT (Dynamic Information Flow Tracking) on ARM-based SoCs (e.g. Xilinx Zynq). Current DIFT implementations suffer from two major drawbacks. First, recovering required information for DIFT is generally based on software instrumentation leading to high time overheads. ARMHEx takes profit of ARM CoreSight debug components and static analysis to drastically reduce instrumentation time overhead (up to 90% compared to existing works). Then, security of the DIFT hardware extension itself is not considered in related works. In this work, we tackle this issue by proposing a solution based on ARM Trustzone.

The expansion of information technology infrastructure is encountered with Advanced Persistent Threats (APTs), which can launch data destruction, disclosure, modification, and/or Denial of Service attacks by drawing upon vulnerabilities of software and hardware. Moving Target Defense (MTD) is a promising risk mitigation technique that replies to APTs via implementing randomisation and dynamic strategies on compromised assets. However, some MTD techniques adopt the blind random mutation, which causes greater performance overhead and worse defense utility. In this paper, we formulate the cyber-attack and defense as a dynamic partially observable Markov process based on dynamic Bayesian inference. Then we develop an Inference-Based Adaptive Attack Tolerance (IBAAT) system , which includes two stages. In the first stage, a forward–backward algorithm with a time window is employed to perform a security risk assessment. To select the defense strategy, in the second stage, the attack and defense process is modelled as a two-player general-sum Markov game and the optimal defense strategy is acquired by quantitative analysis based on the first stage. The evaluation shows that the proposed algorithm has about 10% security utility improvement compared to the state-of-the-art.

Dynamic information flow tracking (also known as taint tracking) is an appealing approach to combat various security attacks. However, the performance of applications can severely degrade without hardware support for tracking taints. This paper observes that information flow tracking can be efficiently emulated using deferred exception tracking in microprocessors supporting speculative execution. Based on this observation, we propose SHIFT, a low-overhead, software-based dynamic information flow tracking system to detect a wide range of attacks. The key idea is to treat tainted state (describing untrusted data) as speculative state (describing deferred exceptions). SHIFT leverages existing architectural support for speculative execution to track tainted state in registers and needs to instrument only load and store instructions to track tainted state in memory using a bitmap, which results in significant performance advantages. Moreover, by decoupling mechanisms for taint tracking from security policies, SHIFT can detect a wide range of exploits, including high-level semantic attacks. We have implemented SHIFT using the Itanium processor, which has support for deferred exceptions, and by modifying GCC to instrument loads and stores. A security assessment shows that SHIFT can detect both low-level memory corruption exploits as well as high-level semantic attacks with no false positives. Performance measurements show that SHIFT incurs about 1% overhead for server applications. The performance slowdown for SPEC-INT2000 is 2.81X and 2.27X for tracking at byte-level and wordlevel respectively. Minor architectural improvements to the Itanium processor (adding three simple instructions) can reduce the performance slowdown down to 2.32X and 1.8X for byte-level and word-level tracking, respectively.

Advanced Persistent Threats (APTs) commonly use stepping stone attacks that allow the adversary to move laterally undetected within an enterprise network towards a target. Existing network security techniques provide limited protection against such attacks, because they lack intra-network mediation and the context of information semantics. We propose PivotWall, a network security defense that extends information flow tracking on each host into network-level defenses. PivotWall uses a novel combination of information-flow tracking and Software Defined Networking (SDN) to detect a wide range of attacks used by advanced adversaries, including those that abuse both application- and network-layer protocols. It further enables a variety of attack responses including traffic steering, as well as advanced mechanisms for forensic analysis. We show that PivotWall incurs minimal impact on network throughput and latency for untainted traffic and less than 58% overhead for tainted traffic. As such, we demonstrate the utility of information flow tracking as a defense against advanced network-level attacks.

Dynamic information flow tracking (DIFT) has been an effective security countermeasure for both low-level memory corruptions and high-level semantic attacks. However, many software approaches suffers from large performance degradation and hardware approaches have great logic and storage overhead. In this paper, we propose a flexible, efficient, and light-weight approach to perform DIFT based on secure page allocation, PIFT. Instead of associating each data value with a taint tag, we aggregate data according to their taints, i.e., putting data with different attributes in different types of memory pages. Our approach is a compile-aided process that allows the compiler to allocate trusted/untrusted information into different memory pages. Our implementation and analysis show that the memory overhead is little, and the approach can protect critical information, like return address, indirect jump address, and system call arguments, from being overwritten by malicious data.

Today’s threats use multiple means of propagation, such as social engineering, email, and application vulnerabilities, and often operate in different phases, such as single device compromise, lateral network movement, and data exfiltration. These complex threats rely on advanced persistent threats supported by well-advanced tactics for appearing unknown to traditional security defenses. As organizations realize that attacks are increasing in size and complexity, cyber threat intelligence (TI) is growing in popularity and use. This trend followed the evolution of advanced persistent threats, as they require a different level of response that is more specific to the organization. TI can be obtained via many formats, with open-source intelligence one of the most common, and using threat intelligence platforms (TIPs) that aid organizations to consume, produce, and share TI. TIPs have multiple advantages that enable organizations to quickly bootstrap the core processes of collecting, analyzing, and sharing threat-related information. However, current TIPs have some limitations that prevent their mass adoption. This article proposes AECCP, a platform that addresses some of the TIPs limitations. AECCP improves quality TI by classifying it accordingly a single unified taxonomy , removing the information with low value, enriching it with valuable information from open-source intelligence sources, and aggregating it for complementing information associated with the same threat. AECCP was validated and evaluated with three datasets of events and compared with two other platforms, showing that it can generate quality TI automatically and help security analysts analyze security incidents in less time.

This research uses a time-aware hypergraph design and anomaly-detection methods to simulate cyberattack sequences. Multi-phase cyber-attacks have high-order interactions, concurrency, and unpredictable timing that traditional directed graph models cannot describe. To overcome this constraint, we create hypergraphs with cyber kill-chain stages including reconnaissance, initial access, execution, persistence, privilege escalation, and exfiltration as nodes and hyperedges for logical and temporal groups. Randomized temporal information is added to each simulated phase to create a two-hour enemy timeline. Repetitive simulations introduce regulated phase length and sequence ordering diversity. Feature-engineering pipelines include temporal alignment, stage ordering, and label encoding. Scatter-based anomaly plots and frequency-distribution histograms show aberrant phase lengths from an Isolation Forest model. A transition-probability matrix quantifies hypergraph stage-to-stage movement and better models adversarial behavior. Structured datasets from simulations are provided for IDS training, red-team emulation, and threat-analysis investigations. The proposed time-aware hypergraph better reconstructs Advanced Persistent Threat (APT) behavior by capturing overlapping phases, higher-order relationships, and temporal uncertainty than DAG-based representations. The research compares the proposed hypergraph model to a baseline DAG model using the same synthetic dataset to demonstrate demonstrable changes in anomaly-detection performance and IDS-dataset quality to assure scientific validity. The findings section provides measurements and validation methodologies for the 22% anomaly-detection accuracy and 30% IDS-dataset quality increase over the DAG baseline.

Hardware information flow tracking based on lightweight path awareness