基于分支函数的混淆技术研究

静态反汇编是对程序进行逆向工程的第一步,它将程序的可执行机器码以汇编指令代码的形式表示,给盗用软件知识产权和发掘软件漏洞提供了可能。为了混淆静态反汇编过程,增加对程序进行反汇编的难度,本文深入研究基于分支函数的静态反汇编混淆技术,针对其隐蔽性较差和代码执行效率低下的缺点,提出一种改进的分支函数静态反汇编混淆技术。改进后的混淆技术不仅能够有效地隐藏程序中的跳转指令,提高了代码的执行效率,同时增加了软件逆向工程分析的难度。     

一种基于中断处理机制的动态反汇编算法

传统的反汇编是静态进行的,它难以处理逻辑陷阱、花指令、代码中的数据、动态控制流等问题,这就导致其最终的反汇编结果可能不完整,存在错误.一段特意设计的代码,可以用动态控制流替代静态控制流;一段特意设计的花指令,可以让静态控制流关系任意复杂,这都将使静态反汇编分析难以进行.让代码运行起来,动态地进行反汇编,可以解决上述静态反汇编遇到的问题.结合计算机的中断处理机制,使得代码的实际执行路径是可知的.针对实际执行到的计算机指令进行反汇编,确保了反汇编结果的准确性;反复执行代码,在时间上进行积累,可以确保反汇编结果的完整性不断增加并趋于完整.     

基于控制流的静态反汇编算法研究

该文在分析各种类型的指令对程序静态流程影响的基础上,提出了一种基于程序流程遍历图的静态反汇编算法,并给出了一种基于统计学的代码间隙填充技术对由间接跳转和间接调用所引用的代码区进行反汇编的方法。     

基于程序流敏感的自修改代码混淆方法

自修改代码混淆方法是一种隐藏程序重要信息的有效技术。为减少代码混淆造成的额外开销而又不影响代码混淆的质量,利用程序流敏感分析方法选择比较重要的指令进行混淆。为提高代码混淆的质量,有效地防止反汇编,提出一个二步比较混淆模型。该模型包括两个子混淆器,混淆器1采用程序流敏感分析方法获得混淆的指令并产生两个混淆代码文件和一个混淆代码映射文件。混淆器2通过比较两个混淆代码文件精确地定位混淆指令在二进制代码中的位置,然后利用混淆代码映射文件对二进制代码进行混淆,以进一步提高代码混淆的质量。通过实验分析,混淆后二进制文件的额外开销只占整个代码的3%左右,并且混淆后的反汇编代码明显异于原始的反汇编代码,甚至出现了一些无法识别的错误指令。     

基于符号执行和N-scope复杂度的代码混淆度量方法

代码混淆可有效对抗逆向工程等各类 MATE 攻击威胁,作为攻击缓和性质的内生安全技术发展较为成熟,对代码混淆效果的合理度量具有重要价值。代码混淆度量研究相对较少,针对代码混淆弹性的度量方法与泛化性、实用性度量方法相对缺乏。符号执行技术广泛应用于反混淆攻击,其生成遍历程序完整路径输入测试集的难度可为混淆弹性度量提供参考,然而基于程序嵌套结构的对抗技术可显著降低符号执行效率,增加其混淆弹性参考误差。针对上述问题,提出结合符号执行技术和N-scope复杂度的代码混淆度量方法,该方法首先基于程序符号执行时间定义程序混淆弹性;其次提出适配符号执行的N-scope复杂度,定义程序混淆强度同时增强符号执行对多层嵌套结构程序的混淆弹性度量鲁棒性;进而提出结合动态分析与静态分析的混淆效果关联性分析,通过对程序进行符号执行与控制流图提取量化混淆效果。面向 C 程序构建了该度量方法的一种实现框架并验证,实验对3个公开程序集及其混淆后程序集约4 000个程序进行混淆效果度量,度量结果表明,提出的度量方法在较好地刻画混淆效果的同时拥有一定的泛化能力与实用价值;模拟真实混淆应用场景给出了该度量方法的使用样例,为混淆技术使用人员提供有效的混淆技术度量与技术配置参考。     

一种动静态结合的代码反汇编技术

为在不修改二进制代码的情况下提高反汇编的准确性和覆盖率,提出一种静态分析与动态仿真相结合的反汇编技术。在传统静态反汇编算法的基础上,利用代码仿真环境构造动态基本块标记算法,通过监控代码的执行路径达到反汇编求精的目的。测试结果证明了该方法的有效性。     

路径模糊:一种有效抵抗符号执行的二进制混淆技术

符号执行能够对软件的路径分支信息进行收集和形式化表示,然后通过路径可达性推理得到软件行为同用户输入、网络输入等外部执行环境间的依赖关系.这些依赖关系已被广泛地应用到漏洞发掘、代码复用、协议分析等领域.该逆向分析技术也可被黑客用于软件破解、篡改和盗版等,对软件知识产权的保护带来了新的威胁.提出了一种新的基于路径模糊的软件保护方法以抵抗基于符号执行的逆向分析:利用条件异常代码替换条件跳转指令来隐藏程序的路径分支信息,使用不透明谓词技术引入伪造的路径分支来弥补程序在统计属性上的差异,并对路径模糊技术的强度、弹性和开销进行了分析.实验结果表明路径模糊技术能保护各类路径分支条件,有效减少路径分支信息的泄露,抵抗基于符号执行的逆向分析.     

形状分析符号执行引擎中的状态合并

符号执行技术以其良好的精确度控制和代码覆盖率被广泛应用于静态程序分析和高覆盖率测试用例自动生成。 符号执行 在分析程序时,以模拟真实的程序执行过程的方式分析程序的数据流和控制流信息,并检查程序可能出现的所有状态,得到程序的分析结果。高精确度和高覆盖率要求对程序状态描述具体而完备,这会导致符号执行过程中常见的状态爆炸问题。首先提出在不同的执行路径上对具体内存状态进行合并的算法,然后对内存模型进行适度的抽象,扩大状态合并算法的适用范围,最后讨论状态合并所带来的实际效果,并提出了状态合并的优化解决方案。所提出的算法在符号执行引擎ShapeChecker上实现,并取得了良好的实验结果。     

反静态反汇编技术研究

通过对软件可执行二进制码的静态反汇编结果进行分析,可以对其进行非法的修改或窃取其知识产权。为了防范这种情况,在描述静态反汇编基本算法的基础上,提出了分支函数和跳转表欺骗两种隐藏程序控制流的反静态反汇编技术。这两种技术能够隐藏程序中跳转指令的真实目标地址,并能够伪造出导致静态反汇编器出错的假目标地址,从而提高程序的反静态反汇编性能,增加软件分析的难度。     

基于中断向量表重构的固件代码反汇编技术

反汇编是固件代码逆向分析的重要研究内容,其正确性直接影响固件代码逆向分析的准确性。固件代码结构具有特殊性,针对上层应用程序的反汇编算法大都不能直接用于固件代码的反汇编。中断向量表是固件代码的重要组成部分,从中断向量开始对中断服务子程序进行反汇编,可提高固件代码反汇编的精度。通过对固件代码结构特点的研究分析,介绍了中断向量表的重构方法,提出了一种基于中断向量表重构的固件代码反汇编技术。经测试分析,与传统的静态反汇编技术相比,基于中断向量表重构的固件代码反汇编技术不仅能够对固件代码中的主函数进行反汇编,还能够对中断服务子程序进行反汇编,反汇编精度平均提高了8.72%。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.