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排序方式: 共有24条查询结果,搜索用时 15 毫秒
1.
近年来,Shellcode攻击通常利用多态技术进行自我加密来绕过网络层设备的检测,而现有检测方法无法区分多态Shellcode与加壳保护代码.提出了一种基于双模式虚拟机的多态Shellcode检测方法,该方法改进了现有的GetPC定位机制,实现了Shellcode的初步定位,通过IA-32指令识别对网络流量的进行进一步过滤,利用有限自动机及其判别条件实现虚拟机控制流模式和数据流模式之间的切换,并通过结合现有的特征匹配技术实现对多层加密的多态Shellcode的检测.实验结果表明,针对大量真实的网络数据,该方法在保证高检测召回率的同时,能够实现对多态Shellcode与加壳保护软件的有效区分,避免了对正常流量的误报行为,并且时间开销介于静态分析与动态模拟之间,为网络层检测多态Shellcode提供了一种有效方法.  相似文献   
2.
针对面向对象语言的特点,结合异常处理机制,对传统的系统依赖图(SDG图)进行了扩展,实现了面向对象的系统依赖图(OSDG图).改进后的OSDG图可以很好地支持继承和多态等特征,并能处理多态对象抛出和处理异常所带来的数据和控制依赖关系.通过传统的程序切片算法,可以在OSDG上切出较为精确的切片.  相似文献   
3.
薛永岭  黄皓  张博 《计算机工程》2009,35(9):133-135
针对恶意篡改程序控制流攻击方式,提出一种监控程序控制流完整性的方法。对程序源代码进行扫描,以函数作为识别程序行为的基本粒子,利用函数调用执行的序列信息,建立表现程序原意的行为轨迹模型,利用该模型在运行期监控程序的执行流程。实验结果表明,该方法对篡改控制流的攻击起到了很好的防御作用。  相似文献   
4.
Useless-variable elimination is a transformation that eliminates variables whose values does not affect the result of a computation. We present a type-based method for useless-variable elimination and prove its correctness. The algorithm is a surprisingly simple extension of the usual type-reconstruction algorithm. Our method has several attractive features. First, it is simple, so that the proof of the correctness is clear and the method can be easily extended to deal with a polymorphic language. Second, it is efficient: for a simply-typed -calculus, it runs in time almost linear in the size of an input expression. Moreover, our transformation is optimal in a certain sense among those that preserve well-typedness, both for the simply-typed language and for an ML-style polymorphically-typed language.  相似文献   
5.
随机化技术防御进程控制流劫持攻击, 是建立在攻击者无法了解当前内存地址空间布局的基础之上, 但是, 攻击者可以利用内存信息泄露绕过随机化防御获得 gadget 地址, 向程序注入由 gadget 地址构造的 payload, 继续实施控制流劫持攻击, 窃取敏感数据并夺取或破坏执行软件的系统。目前, 异构冗余执行系统是解决该问题的方法之一, 基本思想是同一程序运行多个多样化进程, 同时处理等效的程序输入。随机化技术使冗余的进程对恶意输入做出不同的输出, 同时正常功能不受影响。近年来,一些符合上述描述的系统已经被提出, 分析进程异构冗余执行系统的表决设计可以发现, 基于 ptrace 的实现方法会引入大量的上下文切换, 影响系统的执行效率。率先直接修改内核设计出一种进程异构冗余执行系统, 表决过程完全在内核中完成, 冗余的进程独立地采用内存地址空间随机化技术, 构建相互异构的内存地址空间布局, 在与内存信息泄露相关的系统调用处进行表决,发现泄露信息不一致, 阻断进程控制流劫持攻击。即使攻击者跳过内存信息泄露进行漏洞利用, 异构内存空间布局也使得注入由 gadget 地址构造的 payload 无法同时在冗余的进程中有效, 阻断进程控制流劫持攻击。实现了原型系统 KMBox, 实验证明该系统能够有效抵御进程控制流劫持攻击, 性能相较于基于 ptrace 的进程异构冗余执行系统有所提高。  相似文献   
6.
We address the problem of code generation for embedded DSP systems. In such systems, it is typical for one or more digital signal processors (DSPs), program memory, and custom circuitry to be integrated onto a single IC. Consequently, the amount of silicon area that is dedicated to program memory is limited, so the embedded software must be sufficiently dense. Additionally, this software must be written so as to meet various high-performance constraints, which may include hard real-time constraints. Unfortunately, existing compiler technology is unable to generate dense, high-performance code for DSPs since it does not provide adequate support for the specialized architectural features of DSPs. These specialized features not only allow for the fast execution of common DSP operations, but they also allow for the generation of dense assembly code that specifies these operations. Thus, system designers often hand-program the embedded software in assembly, which is a very time-consuming task. In this paper, we focus on providing compiler support for one particular specialized architectural feature, namely the paged absolute addressing mode – this feature is found in two commercial DSPs, the Texas Instruments' TMS320C25 and TMS320C50 fixed-point DSPs; however, it may also be featured in application-specific processors (ASIPs). We present some machine-dependent code optimizations that improve code density by exploiting this architectural feature. Experimental results demonstrate that for a set of typical DSP benchmarks, some of our optimizations reduce overall code size and data memory consumption by an average of 5.0% and 16.0%, respectively. Our experimental vehicle throughout this research is the TMS320C25.  相似文献   
7.
函数返回类型恢复分为库函数和用户函数返回类型恢复两类。分析IA-64体系结构在函数调用和返回方面的特性得知,用户函数返回类型恢复不是只能从调用者的角度进行分析,还可从被调用者的角度进行分析。综合两种分析方法的优缺点,提出了一种全新的函数返回类型恢复方法。介绍了静态二进制翻译系统ITA中基于控制流和数据流分析的函数返回类型恢复技术,并给出相应的实现算法。由IA-64体系结构的实例验证证明,该方法是一种实用的函数返回类型恢复方法。  相似文献   
8.
控制流劫持攻击利用程序内存漏洞获取程序的控制权,进而控制程序执行恶意代码,对系统安全造成极大的威胁.为了应对控制流劫持攻击,研究人员提出了一系列的防御手段.控制流完整性是一种运行时防御方法,通过阻止进程控制流的非法转移,来确保控制流始终处于程序要求的范围之内.近年来,越来越多的研究致力于解决控制流完整性的相关问题,例如提出新的控制流完整性方案、新的控制流完整性方案评估方法等.首先阐述了控制流完整性的基本原理,然后对现有控制流完整性方案进行了分类,并分别进行了分析,同时介绍了现有针对控制流完整性方案的评估方法与评价指标.最后,对控制流完整性的未来工作进行了展望,以期对未来的控制流完整性研究提供参考.  相似文献   
9.
Feng  Yu-Jing  Li  De-Jian  Tan  Xu  Ye  Xiao-Chun  Fan  Dong-Rui  Li  Wen-Ming  Wang  Da  Zhang  Hao  Tang  Zhi-Min 《计算机科学技术学报》2022,37(4):942-959

The dataflow architecture, which is characterized by a lack of a redundant unified control logic, has been shown to have an advantage over the control-flow architecture as it improves the computational performance and power efficiency, especially of applications used in high-performance computing (HPC). Importantly, the high computational efficiency of systems using the dataflow architecture is achieved by allowing program kernels to be activated in a simultaneous manner. Therefore, a proper acknowledgment mechanism is required to distinguish the data that logically belongs to different contexts. Possible solutions include the tagged-token matching mechanism in which the data is sent before acknowledgments are received but retried after rejection, or a handshake mechanism in which the data is only sent after acknowledgments are received. However, these mechanisms are characterized by both inefficient data transfer and increased area cost. Good performance of the dataflow architecture depends on the efficiency of data transfer. In order to optimize the efficiency of data transfer in existing dataflow architectures with a minimal increase in area and power cost, we propose a Look-Ahead Acknowledgment (LAA) mechanism. LAA accelerates the execution ow by speculatively acknowledging ahead without penalties. Our simulation analysis based on a handshake mechanism shows that our LAA increases the average utilization of computational units by 23.9%, with a reduction in the average execution time by 17.4% and an increase in the average power efficiency of dataflow processors by 22.4%. Crucially, our novel approach results in a relatively small increase in the area and power consumption of the on-chip logic of less than 0.9%. In conclusion, the evaluation results suggest that Look-Ahead Acknowledgment is an effective improvement for data transfer in existing dataflow architectures.

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10.
为解决基于COTS处理器的现代微小卫星系统的软件容错问题,提出了基于虚拟寄存器的软件加固技术(SHVR),它把运行在COTS处理器上的软件故障分为数据流错误和控制流错误,设计了一套虚拟寄存器分配方法来突破现有的只能采用高级语言源程序作为输入的限制,提出了基于虚拟寄存器的数据流和控制流错误检测算法,并在实际应用背景下对这一方案进行了优化.模拟实验和实际应用表明,这套完全基于软件技术的方案在平均付出82.6%性能代价的前提下,对随机注入故障检测率达到91.4%.该方法现已成功应用于哈工大某重大航天课题中.  相似文献   
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