Recently exposed vulnerabilities reveal the necessity to improve the security of branch predictors. Branch predictors record history about the execution of different programs, and such information from different processes are stored in the same structure and thus accessible to each other. This leaves the attackers with the opportunities for malicious training and malicious perception. Instead of flush-based or physical isolation of hardware resources, we want to achieve isolation of the content in these hardware tables with some lightweight processing using randomization as follows. (1) Content encoding. We propose to use hardware-based thread-private random numbers to encode the contents of the branch predictor tables (both direction and destination histories) which we call XOR-BP. Specifically, the data is encoded by XOR operation with the key before written in the table and decoded after read from the table. Such a mechanism obfuscates the information adding difficulties to cross-process or cross-privilege level analysis and perception. It achieves a similar effect of logical isolation but adds little in terms of space or time overheads. (2) Index encoding. We propose a randomized index mechanism of the branch predictor (Noisy-XOR-BP). Similar to the XOR-BP, another thread-private random number is used together with the branch instruction address as the input to compute the index of the branch predictor. This randomized indexing mechanism disrupts the correspondence between the branch instruction address and the branch predictor entry, thus increases the noise for malicious perception attacks. Our analyses using an FPGA-based RISC-V processor prototype and additional auxiliary simulations suggest that the proposed mechanisms incur a very small performance cost while providing strong protection.
MI6: Secure Enclaves in a Speculative Out-of-Order Processor
最近的攻击通过利用允许间接访问共享微体系结构状态的微体系结构侧通道来打破进程隔离。飞地加强了进程抽象以恢复隔离保证。我们提出了MI6，一个积极的，投机性的顺序处理器，能够提供安全的飞地下的威胁模型，包括一个不受信任的操作系统和攻击者能够安装任何软件攻击目前认为是可行的，包括控制流投机攻击。MI6受到Sanctum [16]的启发，并将其隔离保证扩展到更现实的存储层次结构。它还介绍了一个清除指令，这是只使用时，一个安全的进程被调度，并实现了一个复杂的处理器微架构。我们通过在不受信任的Linux操作系统上运行SPEC CINT2006基准测试，在AWS F1 FPGA上进行FPGA仿真，对MI6中的飞地的性能影响进行建模。安全性的代价是受保护程序的平均速度降低约16.4%。
NanoZone: Scalable, Efficient, and Secure Memory Protection for Arm CCA
Hubei Key Laboratory of Distributed System Security, Hubei Engineering Research Center on Big Data Security, School of Cyber Science and Engineering, Huazhong University of Science and Technology（华中科技大学网络空间安全学院）
针对 Arm CCA 难以防御 CVM 内及同进程攻击的问题，本文提出 NanoZone，通过三层轻量级隔离域和用户级 CPI 实现安全高效的细粒度内存保护。
Towards Secure Retrieval-Augmented Generation: A Comprehensive Review of Threats, Defenses and Benchmarks
State Key Laboratory of Mathematical Engineering and Advanced Computing（数学工程与先进计算国家重点实验室）；Information Engineering University（信息工程大学）；Henan Key Laboratory of Information Security（河南省信息安全重点实验室）；University of Chinese Academy of Sciences（中国科学院大学）
