Combining mapping and partitioning exploration for NoC-based embedded systems

Networks on Chip (NoC) have emerged as the key paradigm for designing a scalable communication infrastructure for future Systems on Chip (SoC). An important issue in NoC design is how to map an application on this architecture and how to determine the hardware/software partition that satisfies the performance, cost and flexibility requirements. In this paper, we propose an approach that concurrently optimizes the mapping and the partitioning of streaming applications. The proposed approach exploits multiobjective evolutionary algorithms that are fed by execution performances scores corresponding to the evaluated mappings and partitioning ability to pipeline execution of the streaming application. As result, most promising solutions are highlighted for mapping multimedia applications onto a SoC architecture interconnecting 16 nodes through 2D-Mesh and Ring NoC.     

Improving the yield of NoC-based systems through fault diagnosis and adaptive routing

We propose an effective and low cost method to increase the yield and the lifetime of torus NoCs. The method consists in detecting and diagnosing NoC interconnect faults using BIST structures and activating alternative paths for the faulty links. Alternative paths use the inherent redundancy of the torus topology, thus leading to minimal performance, area, and power overhead. We assume an extended interconnect fault model comprising stuck-at and pairwise shorts within a single link or between any two links in the network. Experimental results for a 3×3 NoC show that the proposed approach can correctly diagnose 93% of all possible interconnect faults and can mitigate 42% of those faults (representing 94.4% of the solvable faults) with a worst case performance penalty of 8% and 1% of area overhead. We also demonstrate the scalability of the method by presenting its application to larger NoCs.     

基于攻击威胁监控的软件保护方法

为了增加软件逆向分析的难度,提高软件的安全性,提出了一种基于攻击威胁监控的软件保护方法。该方法通过在软件中部署威胁监控网,来实时检测并处理软件执行过程遇到的多种攻击威胁,确保软件处于一个相对安全的执行环境中,难以被逆向分析。对该保护方法的研究,主要分为以下三个方面：1）攻击威胁描述。分析软件面临的潜在攻击威胁,并按照<威胁目的,实施方式,作用对象>的表示方式对每种威胁进行描述。2）攻击威胁监控网部署。分析各种威胁的特点并设计对应的检测方法,生成节点库;根据节点自身特点,选取合理的部署方案,将节点安插到软件的不同位置。3）原型系统实现与实验设计。按照保护方案的思路实现原型系统,保护一组程序实例,对提出的方案从性能损耗和安全性影响两方面来评估,实验分析结果表明该保护方案是可行且有效的。     

A chosen-plaintext attack on the microsoft BASIC protection

The Microsoft BASIC (MBASIC) interpreter provides a command which protects the program currently in memory by saving it, on disk, in an encrypted format. A user can RUN such a protected program, but cannot access the source program. A chosen-plaintext attack was used to break the encoding; the encryption method could be derived easily from the enciphering of carefully chosen plaintext programs. As a result, a pair of MBASIC programs able to decrypt a protected program for any interpreter was developed. Further, it is shown that a secure system can never be realized, whichever encryption method is used.     

基于Oracleweb环境漏洞攻击与防护技术简

本文从概念、原理以及日常生活中的运用对Oracle web环境注射技术进行阐述,从一个web安全的角度来看如何入侵一台被防火墙防护的Oracle数据库,对一些入侵技术做了web入侵上的总结和延伸。尽量展现一些SQL注射入侵的思路以及如何利用数据库的一些特性,在web上做最大的入侵与防护。     

Masquerade attack on transform-based binary-template protection based on perceptron learning

With the increasing deployment of biometric systems, security of the biometric systems has become an essential issue to which serious attention has to be given. To prevent unauthorized access to a biometric system, protection has to be provided to the enrolled biometric templates so that if the database is compromised, the stored information will not enable any adversary to impersonate the victim in gaining an illegal access. In the past decade, transform-based template protection that stores binary one-way-transformed templates (e.g. Biohash) has appeared being one of the benchmark template protection techniques. While the security of such approach lies in the non-invertibility of the transform (e.g. given a transformed binary template, deriving the corresponding face image is infeasible), we will prove in this paper that, irrespective of whether the algorithm of transform-based approach is revealed, a synthetic face image can be constructed from the binary template and the stolen token (storing projection and discretization parameters) to obtain a highly-probable positive authentication response. Our proposed masquerade attack algorithms are mainly composed of a combination of perceptron learning and customized hill climbing algorithms. Experimental results show that our attack algorithms achieve very promising results where the best setting of our attack achieves 100% and 98.3% rank one recognition rates for the CMU PIE and FRGC databases correspondingly when the binarization algorithm (transformation plus discretization) is known; and 85.29% and 46.57% rank one recognition rates for the CMU PIE and FRGC databases correspondingly when the binarization algorithm is unknown.     

DDOS攻击的分析、检测与防范技术

综述了DDOS的攻击方式的体系结构，并深入分析了DDOS的工作原理和实际的攻击工具，为进一步增强网络的安全性，根据DDOS的攻击的过程与特点，着重提出了一些DDOS的检测模型和防范DDOS攻击的技术手段。     

基于语义聚类的协作推荐攻击检测模型

协作过滤推荐模型目前已被广泛应用于电子商务等环境。由于其对用户偏好数据敏感,因此攻击者可以通过注入伪造的用户偏好数据来影响推荐系统的预测。提出了一个基于语义聚类的协作过滤攻击检测模型,从分析项目的语义入手,针对攻击数据中的随机性,通过分析用户兴趣的组合来评判用户偏好数据的真实与否。大量的实验证明,该模型能有效地检测协作过滤推荐中的注入攻击,从而大大提高了推荐系统的鲁棒性和可靠性。     

工业信息物理系统的攻击建模研究

无线通信网络的脆弱性使得工业信息物理系统易遭受各类网络攻击.为了更深入地了解不同网络攻击的特征进而建立有效的防御措施,构建一种线性时不变离散系统的工业信息物理系统结构;深入研究信息物理系统攻击者攻击空间及攻击者攻击模型,采用控制理论方法研究攻击空间模型的模型知识、披露资源和破坏资源的数学表达;对拒绝服务攻击、重放攻击、虚假数据注入攻击3种典型网络攻击的基本特性,以及对应攻击下攻击模型的表现形式进行分析.通过Simulink/Truetime仿真工具对破坏性和隐蔽性性能进行仿真实验.结果表明,所研究的攻击空间模型及攻击者攻击模型能够有效地描述网络攻击的攻击特性.     

TCP/IP网络协议栈常见攻击技术与防范

本文介绍TCP／IP协议栈中网络层与传输层协议所存在的安全问题及黑客常用的攻击技术,包括网络层的IP源地址欺骗,ARP欺骗,ICMP路由重定向攻击,以及传输层TCP会话劫持,SYNFlood和UDPFlood攻击,并给出防范IP欺骗防范的最佳实践措施。     

OFDM系统中基于训练符号的定时同步算法

正交频分复用(OFDM)作为一种高效的数据传输技术,具有良好的抗衰落能力,应用前景非常广阔。但是OFDM对同步偏差十分敏感,同步偏差的产生会使OFDM系统性能大大降低。在Schmidl-Cox算法的基础上,通过改进训练符号结构来完成符号的定时同步,给出了具体的改进算法,并对改进算法进行了仿真分析。结果表明,改进算法消除了原算法定时测度峰值平台模糊现象,提高了定时估计的精度;且在同等条件下改进算法较原算法有更低的误码率。     

基于多叉树的RFID克隆攻击快速检测

为了提高克隆标签检测的准确度和效率,提出了一个基于多叉树的RFID克隆攻击检测方法(MT-CAI).MT-CAI用一个多叉树防碰撞算法来发现不可调解的碰撞,可以高效地发现所有的克隆标签.从性能分析和仿真实验可以看到,MT-CAI不仅能够检测出所有克隆标签,而且其执行时间远小于GREAT的执行时间.MT-CAI方法在检测时间和检测的准确度方面都优于现有的克隆标签检测协议.     

DDoS attack protection in the era of cloud computing and Software-Defined Networking

Cloud computing has become the real trend of enterprise IT service model that offers cost-effective and scalable processing. Meanwhile, Software-Defined Networking (SDN) is gaining popularity in enterprise networks for flexibility in network management service and reduced operational cost. There seems a trend for the two technologies to go hand-in-hand in providing an enterprise’s IT services. However, the new challenges brought by the marriage of cloud computing and SDN, particularly the implications on enterprise network security, have not been well understood. This paper sets to address this important problem.We start by examining the security impact, in particular, the impact on DDoS attack defense mechanisms, in an enterprise network where both technologies are adopted. We find that SDN technology can actually help enterprises to defend against DDoS attacks if the defense architecture is designed properly. To that end, we propose a DDoS attack mitigation architecture that integrates a highly programmable network monitoring to enable attack detection and a flexible control structure to allow fast and specific attack reaction. To cope with the new architecture, we propose a graphic model based attack detection system that can deal with the dataset shift problem. The simulation results show that our architecture can effectively and efficiently address the security challenges brought by the new network paradigm and our attack detection system can effectively report various attacks using real-world network traffic.     

分布式系统中抵御错误注入攻击的优化设计

安全关键分布式系统面临恶意窃听和错误注入攻击的挑战。以往研究主要针对防止恶意窃听,即考虑提供保密性服务,而忽略了错误注入的安全威胁。针对上述问题,考虑为消息的加解密过程进行错误检测,并最大化系统的错误覆盖率,最小化系统的异构度。首先选取AES对消息进行加解密;然后基于错误检测码确定了五种不同的错误检测方案,并求出了对应的错误覆盖率及时间开销;最后在保证实时性的约束下,提出了一种基于模拟退火(SA)的启发式算法,该算法能最大化系统的错误覆盖率和最小化系统的异构度。实验结果表明,所提算法与贪心算法相比,目标函数值提高了18%以上,该算法具有一定有效性和健壮性。     

Damage assessment and repair in attack resilient distributed database systems

Preventive measures sometimes fail to defect malicious attacks. With attacks on data-intensive applications becoming an ever more serious threat, intrusion tolerant database systems are a significant concern. The main objective of such systems is to detect attacks, and to assess and repair the damage in a timely manner. This paper focuses on efficient damage assessment and repair in distributed database systems. The complexity caused by data partition, distributed transaction processing, and failures makes intrusion recovery much more challenging than in centralized database systems. This paper identifies the key challenges and presents an efficient algorithm for distributed damage assessment and repair.     

工业控制系统APT攻击分析和防御问题探讨

从ICS的发展过程、现代ICS的设计开发、在线ICS的应用环境等角度分析,揭示ICS安全问题的独特型。结合在工控领域发生的ICS-APT安全事件,总结ICS-APT攻击发生的条件和规律,探讨ICS-APT攻击特点及可采取的防御手段,并提出纵深防御、安全生命周期、动态防御机制等未来理论和技术的研究方向。     

基于攻防博弈的SCADA系统信息安全评估方法

信息安全评估是保障SCADA系统正常工作的基础性工作。现有各类评估方法都未考虑攻击者与防御者双方之间的相互影响及经济效益。为了解决这一问题,提出了一种基于攻击防御树和博弈论的评估方法。该方法以攻击防御树为基础,计算攻击者和防御者各自的期望收益函数,并建立系统的攻防博弈模型,求解该完全信息静态博弈模型的混合策略纳什均衡,得到攻防双方的策略选择概率分布结果。针对一个SCADA系统主从站的信息攻防实例进行计算分析,说明了该方法的具体应用。评估结果表明,该方法合理可行,能够帮助风险管理者评估现有系统信息安全防御措施的投资效益,有针对性地重点部署防御措施,实现收益最大化。     

符号序列相关性OFDM系统时间偏移估计

针对受到传播时延、多普勒效应等因素影响的正交频分复用（OFDM）无线系统时间偏移问题,提出了一种基于训练符号序列相关性的时间偏移估计算法CBT。该算法通过对训练符号序列的简单构造,利用其相关性通过时间尺度的最大值找到符号的起始点,实现时间偏移估计,进而有效地提高OFDM系统抗时间偏移的能力。详细的仿真实验以及与现有PML算法的性能比较表明,提出的时间偏移估计算法CBT在加性高斯白噪声（AWGN）与瑞利衰落信道下都明显地减小了时间偏移误差。     

基于代价敏感支持向量机的推荐系统托攻击检测方法

基于标准支持向量机的托攻击检测方法不能体现由于用户误分代价不同对分类效果带来的影响,提出了一种基于代价敏感支持向量机的托攻击检测新方法,该方法在代价敏感性学习机制下引入支持向量机作为分类工具,对支持向量机输出进行后验概率建模,建立了基于类别隶属度的动态代价函数,更准确地反映不同样本的分类代价,在此基础上设计了代价敏感支持向量机分类器。将该分类器应用在推荐系统托攻击检测中,并与标准的支持向量机方法、代价敏感支持向量机方法进行比较,实验结果表明,本方法可以更精确地控制代价敏感性,进一步提高对攻击用户的检测精度,降低总体的误分类代价。     

ACSP: A novel security protocol against counting attack for UHF RFID systems

Current research on UHF RFID system security mainly focus on protecting communication safety and information privacy between a pair of specific tags and its corresponding interrogation reader. However, instead of stealing detailed private information of tags, adversaries may just want to estimate the cardinality of tags, which is named counting attack. Unfortunately, most existing protocols are vulnerable to counting attack. To defend against this attack, in this paper we propose ACSP, a novel Anti-Counting Security Protocol. ACSP employs session identifier and provides a corresponding authentication metric to verify the commands sent by the reader. To handle counting attack, ACSP periodically updates the session identifier, and securely identifies tags with encryption. We evaluate the performance of ACSP through theoretical analysis and qualitative comparison. Results show that ACSP can efficiently withstand counting attack as well as defending against regular security threats as existing protocols.