In recent years, control flow attacks targeting Intel SGX have attracted significant attention from the security community due to their potent capacity for information leakage. Although numerous software-based defenses have been developed to counter these attacks, many remain inadequate in fully addressing other, yet-to-be-discovered side channels.

This paper introduces HoBBy, a compiler-based tool that hardens unbalanced branches at the instruction level, making parallel control flows indistinguishable to state-of-theart attacks that bypass the source-code level balancing. To achieve this, we propose a single-step analysis method to identify unbalanced instructions in secret-dependent branches, and implement instruction shadowing, cogging, and spiraling techniques to protect them. We evaluate HoBBy by hardening secret-dependent branches in four real-world applications, validating its resilience against three state-of-the-art attacks targeting Intel SGX and AMD SEV. HoBBy achieves a runtime overhead of 2.8% for cryptographic libraries and a binary size overhead of $\mathbf{0. 6 \%}$.

A common way for attackers to compromise victim systems is hijacking sensitive operations (e.g., control-flow transfers) with attacker-controlled inputs. Existing solutions in general only protect parts of these targets and have high performance overheads, which are impractical and hard to deploy on systems with limited resources (e.g., IoT devices) or for low-level software like kernels and bare-metal firmware. In this paper, we present a lightweight hardware-software co-design solution ROLoad-PMP to protect sensitive operations from being hijacked for low-level software. First, we propose new instructions, which only load data from read-only memory regions with specific keys, to guarantee the integrity of pointees pointed by (potentially corrupted) data pointers. Then, we provide a program hardening mechanism to protect sensitive operations, by classifying and placing their operands into read-only memory with different keys at compile-time and loading them with ROLoad-PMP-family instructions at runtime. We have implemented an FPGA-based prototype of ROLoad-PMP based on RISC-V, and demonstrated an important defense application, i.e., forward-edge control-flow integrity. Results showed that ROLoad-PMP only costs few extra hardware resources ($\lt 1.40\%$). Moreover, it enables many lightweight (e.g., with negligible overheads$\lt 0.853\%$) defenses, and provides broader and stronger security guarantees than existing hardware solutions, e.g., ARM BTI and Intel CET.

Page tables are critical data structures in kernels, serving as the trust base of most mitigation solutions. Their integrity is thus crucial but is often taken for granted. Existing page table protection solutions usually provide insufficient security guarantees, require heavy hardware, or introduce high overheads. In this paper, we present a novel lightweight hardware-software co-design solution, PTStore, consisting of a secure region storing page tables and tokens verifying page table pointers. Evaluation results on FPGA-based prototypes show that PTStore only introduces <0.92% hardware overheads and <0.86% performance overheads, but provides strong security guarantees, showing that PTStore is efficient and effective.

Hyperspectral imaging has become a popular imaging technique in the medical field, and the development of algorithms for computer-aided diagnosis (CAD) is urgently required. Traditional deep learning techniques require a lot of annotated data, which is a burden on doctors. Self-supervised learning (SSL) is a solution for extracting feature representations from unlabeled data. However, traditional CNN-based SSL algorithms cannot explore relations between neighboring and long-range spectral bands, which limits classification performance. In this letter, the proposed solution is a novel SSL method using a transformer-based technique called masked spectral bands modeling with shifted windows (MSBMSW). This method predicts masked spectral bands as the pretext task and uses a self-attention mechanism with shifted windows to capture the divergence of neighboring spectral bands and enhance information exchange between long-range spectral bands. Experimental results demonstrate that MSBMSW achieves better classification results than many state-of-the-art methods and has potential clinical value for CAD of MHSIs.

Memory safety is a key security property that stops memory corruption vulnerabilities. Different types of memory safety enforcement solutions have been proposed and adopted by sanitizers or mitigations to catch and stop such bugs, at the development or deployment phase. However, existing solutions either provide partial memory safety or have overwhelmingly high performance overheads.

The spatial heterogeneity is an important indicator of the malignancy of lung nodules in lung cancer diagnosis. Compared with 2D nodule CT images, the 3D volumes with entire nodule objects hold richer discriminative information. However, for deep learning methods driven by massive data, effectively capturing the 3D discriminative features of nodules in limited labeled samples is a challenging task. Different from previous models that proposed transfer learning models in a 2D pattern or learning from scratch 3D models, we develop a self-supervised transfer learning based on domain adaptation (SSTL-DA) 3D CNN framework for benign-malignant lung nodule classification. At first, a data pre-processing strategy termed adaptive slice selection (ASS) is developed to eliminate the redundant noise of the input samples with lung nodules. Then, the self-supervised learning network is constructed to learn robust image representations from CT images. Finally, a transfer learning method based on domain adaptation is designed to obtain discriminant features for classification. The proposed SSTL-DA method has been assessed on the LIDC-IDRI benchmark dataset, and it obtains an accuracy of 91.07% and an AUC of 95.84%. These results demonstrate that the SSTL-DA model achieves quite a competitive classification performance compared with some state-of-the-art approaches.

Scene classification of high spatial resolution (HSR) images can provide data support for many practical applications, such as land planning and utilization, and it has been a crucial research topic in the remote sensing (RS) community. Recently, deep learning methods driven by massive data show the impressive ability of feature learning in the field of HSR scene classification, especially convolutional neural networks (CNNs). Although traditional CNNs achieve good classification results, it is difficult for them to effectively capture potential context relationships. The graphs have powerful capacity to represent the relevance of data, and graph-based deep learning methods can spontaneously learn intrinsic attributes contained in RS images. Inspired by the abovementioned facts, we develop a deep feature aggregation framework driven by graph convolutional network (DFAGCN) for the HSR scene classification. First, the off-the-shelf CNN pretrained on ImageNet is employed to obtain multilayer features. Second, a graph convolutional network-based model is introduced to effectively reveal patch-to-patch correlations of convolutional feature maps, and more refined features can be harvested. Finally, a weighted concatenation method is adopted to integrate multiple features (i.e., multilayer convolutional features and fully connected features) by introducing three weighting coefficients, and then a linear classifier is employed to predict semantic classes of query images. Experimental results performed on the UCM, AID, RSSCN7, and NWPU-RESISC45 data sets demonstrate that the proposed DFAGCN framework obtains more competitive performance than some state-of-the-art methods of scene classification in terms of OAs.

Sensitive operations (e.g. control-flow transfers) are attractive targets for attackers. To protect them from being hijacked, we propose a new solution ROLoad to guarantee the integrity of their operands, which are loaded from (potentially corrupted) memory. We extend the RISC-V instruction set, implement an FPGA-based prototype of ROLoad, and then demonstrate two specific defense applications. Results show that this solution only costs few extra hardware resources (< 3.32%). However, it could enable many lightweight (e.g. with overheads less than 0.31%) defenses, and provide broader and stronger security guarantees than existing hardware solutions, e.g. ARM BTI and Intel CET.

In this letter, a new semisupervised dimensionality reduction (DR) method, termed geodesic-based manifold joint hypergraphs (GMJHs), is proposed for hyperspectral image (HSI). This method first builds a geodesic-based reconstruction model to discover the nonlinear similarity between two manifold reconstruction neighborhoods. Then, it implies the probabilistic relationship between unlabeled samples and each class via the geodesic-based reconstruction distance. With the probabilistic class relationship, a supervised hypergraph and an unsupervised hypergraph are constructed to represent the multivariate manifold relationship of samples. Finally, the supervised and unsupervised hypergraphs are jointed for learning optimal projection matrix and enhancing the intraclass compactness in low-dimensional embedding space. Experiments on two HSI data sets show that the proposed GMJH algorithm performs better performance than some state-of-the-art DR methods.

Control-flow integrity (CFI) is a promising technique to mitigate control-flow hijacking attacks. In the past decade, dozens of CFI mechanisms have been proposed by researchers. Despite the claims made by themselves, the security promises of these mechanisms have not been carefully evaluated, and thus are questionable.

The scene classification of high spatial resolution (HSR) images is a challenging task in the remote sensing community. How to construct a discriminative representation of the HSR scene is a key step to improve classification performance. In this letter, we propose a novel feature extraction method termed multilayer feature fusion network (MF2Net) for scene classification. At first, the transferred VGGNet-16 model is employed as a feature extractor to acquire multilayer convolutional features. Then, several layers including pooling, transformation, and fusion layers are designed to process hierarchical features in four branches, and the prediction probability can be obtained for classification. Finally, the proposed model is optimized by fine-tuning techniques, where a novel data augmentation approach is explored to improve generalization ability. As a result, MF2Net effectively applies useful information from multilayers to improve the accuracy of scene classification. The experimental results on AID and NWPU-RESISC45 data sets exhibit that the MF2Net method obtains quite competitive classification results compared with many state-of-the-art methods.