The diagnosis of lymph node metastasis (LNM) is essential for colorectal cancer (CRC) treatment. The primary method of identifying LNM is to perform frozen sections and pathologic analysis, but this method is labor-intensive and time-consuming. Therefore, combining intraoperative fluorescence imaging with deep learning (DL) methods can improve efficiency. The majority of recent studies only analyze uni-modal fluorescence imaging, which provides less semantic information. In this work, we mainly established a multi-modal fluorescence imaging feature fusion prediction (MFI-FFP) model combining white light, fluorescence, and pseudo-color imaging of lymph nodes for LNM prediction. Firstly, based on the properties of various modal imaging, distinct feature extraction networks are chosen for feature extraction, which could significantly enhance the complementarity of various modal information. Secondly, the multi-modal feature fusion (MFF) module, which combines global and local information, is designed to fuse the extracted features. Furthermore, a novel loss function is formulated to tackle the issue of imbalanced samples, challenges in differentiating samples, and enhancing sample variety. Lastly, the experiments show that the model has a higher area under the receiver operating characteristic (ROC) curve (AUC), accuracy (ACC), and F1 score than the uni-modal and bi-modal models and has a better performance compared to other efficient image classification networks. Our study demonstrates that the MFI-FFP model has the potential to help doctors predict LNM and shows its promise in medical image analysis.

Federated learning is a secure machine learning technology proposed to protect data privacy and security in machine learning model training. However, recent studies show that federated learning is vulnerable to backdoor attacks, such as model replacement attacks and distributed backdoor attacks. Most backdoor defense techniques are not appropriate for federated learning since they are based on entire data samples that cannot be hold in federated learning scenarios. The newly proposed methods for federated learning sacrifice the accuracy of models and still fail once attacks persist in many training rounds. In this paper, we propose a novel and effective detection and defense technique called FederatedReverse for federated learning. We conduct extensive experimental evaluation of our solution. The experimental results show that, compared with the existing techniques, our solution can effectively detect and defend against various backdoor attacks in federated learning, where the success rate and duration of backdoor attacks can be greatly reduced and the accuracies of trained models are almost not reduced.

Malicious login, especially lateral movement, has been a primary and costly threat for enterprises. However, there exist two critical challenges in the existing methods. Specifically, they heavily rely on a limited number of predefined rules and features. When the attack patterns change, security experts must manually design new ones. Besides, they cannot explore the attributes' mutual effect specific to login operations. We propose MLTracer, a graph neural network (GNN) based system for detecting such attacks. It has two core components to tackle the previous challenges. First, MLTracer adopts a novel method to differentiate crucial attributes of login operations from the rest without experts' designated features. Second, MLTracer leverages a GNN model to detect malicious logins. The model involves a convolutional neural network (CNN) to explore attributes of login operations, and a co-attention mechanism to mutually improve the representations (vectors) of login attributes through learning their login-specific relation. We implement an evaluation of such an approach. The results demonstrate that MLTracer significantly outperforms state-of-the-art methods. Moreover, MLTracer effectively detects various attack scenarios with a remarkably low false positive rate (FPR).

Conventional attacks of insider employees and emerging APT are both major threats for the organizational information system. Existing detections mainly concentrate on users' behavior and usually analyze logs recording their operations in an information system. In general, most of these methods consider sequential relationship among log entries and model users' sequential behavior. However, they ignore other relationships, inevitably leading to an unsatisfactory performance on various attack scenarios. We propose log2vec, a heterogeneous graph embedding based modularized method. First, it involves a heuristic approach that converts log entries into a heterogeneous graph in the light of diverse relationships among them. Next, it utilizes an improved graph embedding appropriate to the above heterogeneous graph, which can automatically represent each log entry into a low-dimension vector. The third component of log2vec is a practical detection algorithm capable of separating malicious and benign log entries into different clusters and identifying malicious ones. We implement a prototype of log2vec. Our evaluation demonstrates that log2vec remarkably outperforms state-of-the-art approaches, such as deep learning and hidden markov model (HMM). Besides, log2vec shows its capability to detect malicious events in various attack scenarios.