Website Fingerprinting(WF)attacks can extract side channel information from encrypted traffic to form a fingerprint that identifies the victim’s destination website,even if traffic is sophisticatedly anonymized by To...Website Fingerprinting(WF)attacks can extract side channel information from encrypted traffic to form a fingerprint that identifies the victim’s destination website,even if traffic is sophisticatedly anonymized by Tor.Many offline defenses have been proposed and claimed to have achieved good effectiveness.However,such work is more of a theoretical optimization study than a technology that can be applied to real-time traffic in the practical scenario.Because defenders generate optimized defense schemes only if the complete traffic traces are obtained.The practicality and effectiveness are doubtful.In this paper,we provide an in-depth analysis of the difficulties faced in porting existing offline defenses to the online scenarios.And then the online WF defense based on the non-targeted adversarial patch is proposed.To reduce the overhead,we use the Gradient-weighted Class Activation Mapping(Grad-CAM)algorithm to identify critical segments that have high contribution to the classification.In addition,we optimize the adversarial patch generation process by splitting patches and limiting the values,so that the pre-trained patches can be injected and discarded in real-time traffic.Extensive experiments are carried out to evaluate the effectiveness of our defense.When bandwidth overhead is set to 20%,the accuracies of the two state-of-the-art attacks,DF and Var-CNN,drop to 10.83%and 15.49%,respectively.Furthermore,we implement the real-time patch traffic injection based on WFPadTools framework in the online scenario,and achieve a defense accuracy of 95.50%with 12.57%time overhead.展开更多
Tor is pervasively used to conceal target websites that users are visiting. A de-anonymization technique against Tor, referred to as website fingerprinting attack, aims to infer the websites accessed by Tor clients by...Tor is pervasively used to conceal target websites that users are visiting. A de-anonymization technique against Tor, referred to as website fingerprinting attack, aims to infer the websites accessed by Tor clients by passively analyzing the patterns of encrypted traffic at the Tor client side. However, HTTP pipeline and Tor circuit multiplexing techniques can affect the accuracy of the attack by mixing the traffic that carries web objects in a single TCP connection. In this paper, we propose a novel active website fingerprinting attack by identifying and delaying the HTTP requests at the first hop Tor node. Then, we can separate the traffic that carries distinct web objects to derive a more distinguishable traffic pattern. To fulfill this goal, two algorithms based on statistical analysis and objective function optimization are proposed to construct a general packet delay scheme. We evaluate our active attack against Tor in empirical experiments and obtain the highest accuracy of 98.64%, compared with 85.95% of passive attack. We also perform experiments in the open-world scenario. When the parameter k of k-NN classifier is set to 5, then we can obtain a true positive rate of 90.96% with a false positive rate of 3.9%.展开更多
基金This work was supported in part by the National Natural Science Foundation of China(Nos.62102084 and 62072103)Jiangsu Provincial Natural Science Foundation of China(No.BK20190340)+2 种基金Jiangsu Provincial Key R&D Program(Nos.BE2021729,BE2022680,and BE2022065-4)Jiangsu Provincial Key Laboratory of Network and Information Security(No.BM2003201)Key Laboratory of Computer Network and Information Integration of Ministry of Education of China(No.93K-9).
文摘Website Fingerprinting(WF)attacks can extract side channel information from encrypted traffic to form a fingerprint that identifies the victim’s destination website,even if traffic is sophisticatedly anonymized by Tor.Many offline defenses have been proposed and claimed to have achieved good effectiveness.However,such work is more of a theoretical optimization study than a technology that can be applied to real-time traffic in the practical scenario.Because defenders generate optimized defense schemes only if the complete traffic traces are obtained.The practicality and effectiveness are doubtful.In this paper,we provide an in-depth analysis of the difficulties faced in porting existing offline defenses to the online scenarios.And then the online WF defense based on the non-targeted adversarial patch is proposed.To reduce the overhead,we use the Gradient-weighted Class Activation Mapping(Grad-CAM)algorithm to identify critical segments that have high contribution to the classification.In addition,we optimize the adversarial patch generation process by splitting patches and limiting the values,so that the pre-trained patches can be injected and discarded in real-time traffic.Extensive experiments are carried out to evaluate the effectiveness of our defense.When bandwidth overhead is set to 20%,the accuracies of the two state-of-the-art attacks,DF and Var-CNN,drop to 10.83%and 15.49%,respectively.Furthermore,we implement the real-time patch traffic injection based on WFPadTools framework in the online scenario,and achieve a defense accuracy of 95.50%with 12.57%time overhead.
基金partially supported by the National Key R&D Program of China(No.2017YFB1003000)the National Natural Science Foundation of China(Nos.61572130,61320106007,61632008,61502100,61532013,and 61402104)+3 种基金the Jiangsu Provincial Natural Science Foundation(No.BK20150637)the Jiangsu Provincial Key Technology R&D Program(No.BE2014603)the Qing Lan Project of Jiangsu Province,Jiangsu Provincial Key Laboratory of Network and Information Security(No.BM2003201)the Key Laboratory of Computer Network and Information Integration of the Ministry of Education of China(No.93K-9)
文摘Tor is pervasively used to conceal target websites that users are visiting. A de-anonymization technique against Tor, referred to as website fingerprinting attack, aims to infer the websites accessed by Tor clients by passively analyzing the patterns of encrypted traffic at the Tor client side. However, HTTP pipeline and Tor circuit multiplexing techniques can affect the accuracy of the attack by mixing the traffic that carries web objects in a single TCP connection. In this paper, we propose a novel active website fingerprinting attack by identifying and delaying the HTTP requests at the first hop Tor node. Then, we can separate the traffic that carries distinct web objects to derive a more distinguishable traffic pattern. To fulfill this goal, two algorithms based on statistical analysis and objective function optimization are proposed to construct a general packet delay scheme. We evaluate our active attack against Tor in empirical experiments and obtain the highest accuracy of 98.64%, compared with 85.95% of passive attack. We also perform experiments in the open-world scenario. When the parameter k of k-NN classifier is set to 5, then we can obtain a true positive rate of 90.96% with a false positive rate of 3.9%.
