Social media has drastically reshaped the world that allows billions of people to engage in such interactive environments to conveniently create and share content with the public. Among them, text data (e.g., tweets, blogs) maintains the basic yet important social activities and generates a rich source of user-oriented information. While those explicit sensitive user data like credentials have been significantly protected by all means, personal private attribute (e.g., age, gender, location) disclosure due to inference attacks is somehow challenging to avoid, especially when powerful natural language processing (NLP) techniques have been effectively deployed to automate attribute inferences from implicit text data. This puts users’ attribute privacy at risk. To address this challenge, in this article, we leverage the inherent vulnerability of machine learning to adversarial attacks, and design a novel text-space Adv ersarial attack for S ocial G ood, called Adv4SG . In other words, we cast the problem of protecting personal attribute privacy as an adversarial attack formulation problem over the social media text data to defend against NLP-based attribute inference attacks. More specifically, Adv4SG proceeds with a sequence of word perturbations under given constraints such that the probed attribute cannot be identified correctly. Different from the prior works, we advance Adv4SG by considering social media property, and introducing cost-effective mechanisms to expedite attribute obfuscation over text data under the black-box setting. Extensive experiments on real-world social media datasets have demonstrated that our method can effectively degrade the inference accuracy with less computational cost over different attribute settings, which substantially helps mitigate the impacts of inference attacks and thus achieve high performance in user attribute privacy protection.

Graphs have emerged as one of the most important and powerful data structures to perform content analysis in many fields. In this line of work, node classification is a classic task, which is generally performed using graph neural networks (GNNs). Unfortunately, regular GNNs cannot be well generalized into the real-world application scenario when the labeled nodes are few. To address this challenge, we propose a novel few-shot node classification model that leverages pseudo-labeling with graph active learning. We first provide a theoretical analysis to argue that extra unlabeled data benefit few-shot classification. Inspired by this, our model proceeds by performing multi-level data augmentation with consistency and contrastive regularizations for better semi-supervised pseudo-labeling, and further devising graph active learning to facilitate pseudo-label selection and improve model effectiveness. Extensive experiments on four public citation networks have demonstrated that our model can effectively improve node classification accuracy with considerably few labeled data, which significantly outperforms all state-of-the-art baselines by large margins.

To mitigate evolving malware attacks, machine learning models have been successfully deployed to detect malware. However, these models are often challenged by data scarcity, design efforts and constrained resources. Inspired by the adversarial vulnerability of machine learning, in this paper, we design a novel model Adv4Mal to adversarially reprogram an ImageNet classification neural network for malware detection in both white-box and black-box settings. As such, a small or moderate amount of data are sufficient to train a promising malware detection model, the varying software features can be uniformly processed without extra efforts, and the majority of computation can be wisely shared and reused to save the resources. This, to the best of our knowledge, has not yet been explored. Specifically, Adv4Mal proceeds by embedding software features into a host image to construct new data, and learning a universal perturbation to be added to all inputs in an imperceptible manner, such that the outputs of the pretrained model can be accordingly mapped to the final detection decisions for all software. We evaluate Adv4Mal on three software datasets. The experimental results demonstrate that Adv4Mal can successfully exploit ImageNet model's learning capability and limited data to achieve high performance in malware detection, and also yield significant advantages of model flexibility to different features, and cost efficiency in computing resources.

The popularization of social media generates a large amount of user-oriented data, where text data especially attracts researchers and speculators to infer user attributes (e.g., age, gender) for fulfilling their intents. Generally, this line of work casts attribute inference as a text classification problem, and starts to leverage graph neural networks for higher-level text representations. However, these text graphs are constructed on words, suffering from high memory consumption and ineffectiveness on few labeled texts. To address this challenge, we design a text-graph-based few-shot learning model for social media attribute inferences. Our model builds a text graph with texts as nodes and edges learned from current text representations via manifold learning and message passing. To further use unlabeled texts to improve few-shot performance, a knowledge distillation is devised to optimize the problem. This offers a trade-off between expressiveness and complexity. Experiments on social media datasets demonstrate the state-of-the-art performance of our model on attribute inferences with considerably fewer labeled texts.

Machine learning, especially deep learning, has emerged as one of the most powerful tools for attribute inference attacks over social media, which poses serious threats to users' privacy and security. In this paper, we explore a novel perspective of protecting data privacy in social media, where we take advantage of the vulnerability of machine learning, and introduce adversarial attacks to forge latent feature representations and mislead attribute inference attacks. Considering that text data in social media shares the most significant privacy of users, we investigate how text-space adversarial attacks can be elaborated to obfuscate users' attributes, and accordingly present a text-space adversarial attack as defense, or AaaD for short. Specifically, we advance AaaD by constructing semantically and visually similar word candidates to perturb, and leveraging word importance scores as selection probabilities to upgrade a population-based optimization to expedite adversarial text generation. We evaluate the performance of AaaD on two social media data sets, while the experimental results validate its effectiveness against inference attacks. Our work yields great value and unveils a new insight on the applicability of adversarial attacks for attribute obfuscation and privacy protection.