Low-entropy masking schemes and shuffling technique are two common countermeasures against traditional side-channel analysis. Improved Rotating S-box Masking (RSM) is a combination of both countermeasures and is implemented by DPA contest committee to improve the software security level of AES-128. Compared with the original version, improved RSM mainly introduces both the offset and shuffle array as security foundations to counteract the existing attacks. In this paper, we first point out a general vulnerability referred to as "leakage fingerprints" and make use of it to successfully crack the offset array with 100% accuracy, which breaks down the masking countermeasure in the first step. Then, we show that cracking the shuffle array is still feasible but not necessary since several other vulnerabilities in the implementation level can be exploited to bypass the shuffle countermeasure directly. By selectively combining all these vulnerabilities, a dozen of attacks can be put forward, and we perform two of them as examples to verify their effectiveness. Official evaluation results show that, both attacks submitted by us are practical and feasible, and also operate with high efficiency. In terms of two major performance metrics, our best scheme requires 4 traces to reveal the AES master key with 80% Global Success Rate (GSR) and only 2 traces are enough to reduce the Maximum Partial Guessing Entropy (PGE) under 10.
{"title":"Leakage Fingerprints: A Non-negligible Vulnerability in Side-Channel Analysis","authors":"Zeyi Liu, Neng Gao, Chenyang Tu, Jian Zhou, Yuan Ma, Yuan Zhao","doi":"10.1145/2897845.2897868","DOIUrl":"https://doi.org/10.1145/2897845.2897868","url":null,"abstract":"Low-entropy masking schemes and shuffling technique are two common countermeasures against traditional side-channel analysis. Improved Rotating S-box Masking (RSM) is a combination of both countermeasures and is implemented by DPA contest committee to improve the software security level of AES-128. Compared with the original version, improved RSM mainly introduces both the offset and shuffle array as security foundations to counteract the existing attacks. In this paper, we first point out a general vulnerability referred to as \"leakage fingerprints\" and make use of it to successfully crack the offset array with 100% accuracy, which breaks down the masking countermeasure in the first step. Then, we show that cracking the shuffle array is still feasible but not necessary since several other vulnerabilities in the implementation level can be exploited to bypass the shuffle countermeasure directly. By selectively combining all these vulnerabilities, a dozen of attacks can be put forward, and we perform two of them as examples to verify their effectiveness. Official evaluation results show that, both attacks submitted by us are practical and feasible, and also operate with high efficiency. In terms of two major performance metrics, our best scheme requires 4 traces to reveal the AES master key with 80% Global Success Rate (GSR) and only 2 traces are enough to reduce the Maximum Partial Guessing Entropy (PGE) under 10.","PeriodicalId":166633,"journal":{"name":"Proceedings of the 11th ACM on Asia Conference on Computer and Communications Security","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129420096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Götzfried, Tilo Müller, Gabor Drescher, S. Nürnberger, M. Backes
We present RamCrypt, a solution that allows unmodified Linux processes to transparently work on encrypted data. RamCrypt can be deployed and enabled on a per-process basis without recompiling user-mode applications. In every enabled process, data is only stored in cleartext for the moment it is processed, and otherwise stays encrypted in RAM. In particular, the required encryption keys do not reside in RAM, but are stored in CPU registers only. Hence, RamCrypt effectively thwarts memory disclosure attacks, which grant unauthorized access to process memory, as well as physical attacks such as cold boot and DMA attacks. In its default configuration, RamCrypt exposes only up to 4 memory pages in cleartext at the same time. For the nginx web server serving encrypted HTTPS pages under heavy load, the necessary TLS secret key is hidden for 97% of its time.
{"title":"RamCrypt: Kernel-based Address Space Encryption for User-mode Processes","authors":"J. Götzfried, Tilo Müller, Gabor Drescher, S. Nürnberger, M. Backes","doi":"10.1145/2897845.2897924","DOIUrl":"https://doi.org/10.1145/2897845.2897924","url":null,"abstract":"We present RamCrypt, a solution that allows unmodified Linux processes to transparently work on encrypted data. RamCrypt can be deployed and enabled on a per-process basis without recompiling user-mode applications. In every enabled process, data is only stored in cleartext for the moment it is processed, and otherwise stays encrypted in RAM. In particular, the required encryption keys do not reside in RAM, but are stored in CPU registers only. Hence, RamCrypt effectively thwarts memory disclosure attacks, which grant unauthorized access to process memory, as well as physical attacks such as cold boot and DMA attacks. In its default configuration, RamCrypt exposes only up to 4 memory pages in cleartext at the same time. For the nginx web server serving encrypted HTTPS pages under heavy load, the necessary TLS secret key is hidden for 97% of its time.","PeriodicalId":166633,"journal":{"name":"Proceedings of the 11th ACM on Asia Conference on Computer and Communications Security","volume":"72 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122565078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Modern websites use multiple authentication cookies to allow visitors to the site different levels of access. The complexity of modern web applications can make it difficult for a web application programmer to ensure that the use of authentication cookies does not introduce vulnerabilities. Even when a programmer has access to all of the source code, this analysis can be challenging; the problem becomes even more vexing when web programmers cobble together off-the-shelf libraries to implement authentication. We have assembled a checklist for modern web programmers to verify that the cookie based authentication mechanism is securely implemented. Then, we developed a tool, Newton, to help a web application programmer to identify authentication cookies for specific parts of the website and to verify that they are securely implemented according to the checklist. We used Newton to analyze 149 sites, including the Alexa top-200 and many other popular sites across a range of categories including search, shopping, and finance. We found that 113 of them---including high-profile sites such as Yahoo, Amazon, and Fidelity---were vulnerable to hijacking attacks. Many websites have already acknowledged and fixed the vulnerabilities that we found using Newton and reported to them.
{"title":"Half-Baked Cookies: Hardening Cookie-Based Authentication for the Modern Web","authors":"Y. Mundada, N. Feamster, B. Krishnamurthy","doi":"10.1145/2897845.2897889","DOIUrl":"https://doi.org/10.1145/2897845.2897889","url":null,"abstract":"Modern websites use multiple authentication cookies to allow visitors to the site different levels of access. The complexity of modern web applications can make it difficult for a web application programmer to ensure that the use of authentication cookies does not introduce vulnerabilities. Even when a programmer has access to all of the source code, this analysis can be challenging; the problem becomes even more vexing when web programmers cobble together off-the-shelf libraries to implement authentication. We have assembled a checklist for modern web programmers to verify that the cookie based authentication mechanism is securely implemented. Then, we developed a tool, Newton, to help a web application programmer to identify authentication cookies for specific parts of the website and to verify that they are securely implemented according to the checklist. We used Newton to analyze 149 sites, including the Alexa top-200 and many other popular sites across a range of categories including search, shopping, and finance. We found that 113 of them---including high-profile sites such as Yahoo, Amazon, and Fidelity---were vulnerable to hijacking attacks. Many websites have already acknowledged and fixed the vulnerabilities that we found using Newton and reported to them.","PeriodicalId":166633,"journal":{"name":"Proceedings of the 11th ACM on Asia Conference on Computer and Communications Security","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131309693","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Cramer-Shoup cryptosystem has attracted much attention from the research community, mainly due to its efficiency in encryption/decryption, as well as the provable reductions of security against adaptively chosen ciphertext attacks in the standard model. At TCC 2005, Vasco et al. proposed a method for building Cramer-Shoup like cryptosystem over non-abelian groups and raised an open problem for finding a secure instantiation. Based on this work, we present another general framework for constructing Cramer-Shoup like cryptosystems. We firstly propose the concept of index exchangeable family (IEF) and an abstract construction of Cramer-Shoup like encryption scheme over IEF. The concrete instantiations of IEF are then derived from some reasonable hardness assumptions over abelian groups as well as non-abelian groups, respectively. These instantiations ultimately lead to simple yet efficient constructions of Cramer-Shoup like cryptosystems, including new non-abelian analogies that can be potential solutions to Vasco et al.'s open problem. Moreover, we propose a secure outsourcing method for the encryption of the non-abelian analog based on the factorization problem over non-commutative groups. The experiments clearly indicate that the computational cost of our outsourcing scheme can be significantly reduced thanks to the load sharing with cloud datacenter servers.
{"title":"Novel Constructions of Cramer-Shoup Like Cryptosystems Based on Index Exchangeable Family","authors":"Jing Li, Licheng Wang, Zonghua Zhang, Xinxin Niu","doi":"10.1145/2897845.2897920","DOIUrl":"https://doi.org/10.1145/2897845.2897920","url":null,"abstract":"The Cramer-Shoup cryptosystem has attracted much attention from the research community, mainly due to its efficiency in encryption/decryption, as well as the provable reductions of security against adaptively chosen ciphertext attacks in the standard model. At TCC 2005, Vasco et al. proposed a method for building Cramer-Shoup like cryptosystem over non-abelian groups and raised an open problem for finding a secure instantiation. Based on this work, we present another general framework for constructing Cramer-Shoup like cryptosystems. We firstly propose the concept of index exchangeable family (IEF) and an abstract construction of Cramer-Shoup like encryption scheme over IEF. The concrete instantiations of IEF are then derived from some reasonable hardness assumptions over abelian groups as well as non-abelian groups, respectively. These instantiations ultimately lead to simple yet efficient constructions of Cramer-Shoup like cryptosystems, including new non-abelian analogies that can be potential solutions to Vasco et al.'s open problem. Moreover, we propose a secure outsourcing method for the encryption of the non-abelian analog based on the factorization problem over non-commutative groups. The experiments clearly indicate that the computational cost of our outsourcing scheme can be significantly reduced thanks to the load sharing with cloud datacenter servers.","PeriodicalId":166633,"journal":{"name":"Proceedings of the 11th ACM on Asia Conference on Computer and Communications Security","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126697526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jan Werner, G. Baltas, R. Dallara, Nathan Otterness, K. Snow, F. Monrose, M. Polychronakis
Memory disclosure vulnerabilities enable an adversary to successfully mount arbitrary code execution attacks against applications via so-called just-in-time code reuse attacks, even when those applications are fortified with fine-grained address space layout randomization. This attack paradigm requires the adversary to first read the contents of randomized application code, then construct a code reuse payload using that knowledge. In this paper, we show that the recently proposed Execute-no-Read (XnR) technique fails to prevent just-in-time code reuse attacks. Next, we introduce the design and implementation of a novel memory permission primitive, dubbed No-Execute-After-Read (near), that foregoes the problems of XnR and provides strong security guarantees against just-in-time attacks in commodity binaries. Specifically, near allows all code to be disclosed, but prevents any disclosed code from subsequently being executed, thus thwarting just-in-time code reuse. At the same time, commodity binaries with mixed code and data regions still operate correctly, as legitimate data is still readable. To demonstrate the practicality and portability of our approach we implemented prototypes for both Linux and Android on the ARMv8 architecture, as well as a prototype that protects unmodified Microsoft Windows executables and dynamically linked libraries. In addition, our evaluation on the SPEC2006 benchmark demonstrates that our prototype has negligible runtime overhead, making it suitable for practical deployment.
{"title":"No-Execute-After-Read: Preventing Code Disclosure in Commodity Software","authors":"Jan Werner, G. Baltas, R. Dallara, Nathan Otterness, K. Snow, F. Monrose, M. Polychronakis","doi":"10.1145/2897845.2897891","DOIUrl":"https://doi.org/10.1145/2897845.2897891","url":null,"abstract":"Memory disclosure vulnerabilities enable an adversary to successfully mount arbitrary code execution attacks against applications via so-called just-in-time code reuse attacks, even when those applications are fortified with fine-grained address space layout randomization. This attack paradigm requires the adversary to first read the contents of randomized application code, then construct a code reuse payload using that knowledge. In this paper, we show that the recently proposed Execute-no-Read (XnR) technique fails to prevent just-in-time code reuse attacks. Next, we introduce the design and implementation of a novel memory permission primitive, dubbed No-Execute-After-Read (near), that foregoes the problems of XnR and provides strong security guarantees against just-in-time attacks in commodity binaries. Specifically, near allows all code to be disclosed, but prevents any disclosed code from subsequently being executed, thus thwarting just-in-time code reuse. At the same time, commodity binaries with mixed code and data regions still operate correctly, as legitimate data is still readable. To demonstrate the practicality and portability of our approach we implemented prototypes for both Linux and Android on the ARMv8 architecture, as well as a prototype that protects unmodified Microsoft Windows executables and dynamically linked libraries. In addition, our evaluation on the SPEC2006 benchmark demonstrates that our prototype has negligible runtime overhead, making it suitable for practical deployment.","PeriodicalId":166633,"journal":{"name":"Proceedings of the 11th ACM on Asia Conference on Computer and Communications Security","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129045943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In data outsourcing, a client stores a large amount of data on an untrusted server; subsequently, the client can request the server to compute a function on any subset of the data. This setting naturally leads to two security requirements: confidentiality of input data, and authenticity of computations. Existing approaches that satisfy both requirements simultaneously are built on fully homomorphic encryption, which involves expensive computation on the server and client and hence is impractical. In this paper, we propose two verifiable homomorphic encryption schemes that do not rely on fully homomorphic encryption. The first is a simple and efficient scheme for linear functions. The second scheme supports the class of multivariate quadratic functions, by combining the Paillier cryptosystem with a new homomorphic message authentication code (MAC) scheme. Through formal security analysis, we show that the schemes are semantically secure and unforgeable.
{"title":"Efficient Verifiable Computation of Linear and Quadratic Functions over Encrypted Data","authors":"Ngoc Hieu Tran, HweeHwa Pang, R. Deng","doi":"10.1145/2897845.2897892","DOIUrl":"https://doi.org/10.1145/2897845.2897892","url":null,"abstract":"In data outsourcing, a client stores a large amount of data on an untrusted server; subsequently, the client can request the server to compute a function on any subset of the data. This setting naturally leads to two security requirements: confidentiality of input data, and authenticity of computations. Existing approaches that satisfy both requirements simultaneously are built on fully homomorphic encryption, which involves expensive computation on the server and client and hence is impractical. In this paper, we propose two verifiable homomorphic encryption schemes that do not rely on fully homomorphic encryption. The first is a simple and efficient scheme for linear functions. The second scheme supports the class of multivariate quadratic functions, by combining the Paillier cryptosystem with a new homomorphic message authentication code (MAC) scheme. Through formal security analysis, we show that the schemes are semantically secure and unforgeable.","PeriodicalId":166633,"journal":{"name":"Proceedings of the 11th ACM on Asia Conference on Computer and Communications Security","volume":"11 2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125764125","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Outsourcing a huge amount of local data to remote cloud servers that has been become a significant trend for industries. Leveraging the considerable cloud storage space, industries can also put forward the outsourced data to cloud computing. How to collect the data for computing without loss of privacy and confidentiality is one of the crucial security problems. Searchable encryption technique has been proposed to protect the confidentiality of the outsourced data and the privacy of the corresponding data query. This technique, however, only supporting search functionality, may not be fully applicable to real-world cloud computing scenario whereby secure data search, share as well as computation are needed. This work presents a novel encrypted cloud-based data share and search system without loss of user privacy and data confidentiality. The new system enables users to make conjunctive keyword query over encrypted data, but also allows encrypted data to be efficiently and multiply shared among different users without the need of the "download-decrypt-then-encrypt" mode. As of independent interest, our system provides secure keyword update, so that users can freely and securely update data's keyword field. It is worth mentioning that all the above functionalities do not incur any expansion of ciphertext size, namely, the size of ciphertext remains constant during being searched, shared and keyword-updated. The system is proven secure and meanwhile, the efficiency analysis shows its great potential in being used in large-scale database.
{"title":"Efficient Multi-Function Data Sharing and Searching Mechanism for Cloud-Based Encrypted Data","authors":"K. Liang, Chunhua Su, Jiageng Chen, Joseph K. Liu","doi":"10.1145/2897845.2897865","DOIUrl":"https://doi.org/10.1145/2897845.2897865","url":null,"abstract":"Outsourcing a huge amount of local data to remote cloud servers that has been become a significant trend for industries. Leveraging the considerable cloud storage space, industries can also put forward the outsourced data to cloud computing. How to collect the data for computing without loss of privacy and confidentiality is one of the crucial security problems. Searchable encryption technique has been proposed to protect the confidentiality of the outsourced data and the privacy of the corresponding data query. This technique, however, only supporting search functionality, may not be fully applicable to real-world cloud computing scenario whereby secure data search, share as well as computation are needed. This work presents a novel encrypted cloud-based data share and search system without loss of user privacy and data confidentiality. The new system enables users to make conjunctive keyword query over encrypted data, but also allows encrypted data to be efficiently and multiply shared among different users without the need of the \"download-decrypt-then-encrypt\" mode. As of independent interest, our system provides secure keyword update, so that users can freely and securely update data's keyword field. It is worth mentioning that all the above functionalities do not incur any expansion of ciphertext size, namely, the size of ciphertext remains constant during being searched, shared and keyword-updated. The system is proven secure and meanwhile, the efficiency analysis shows its great potential in being used in large-scale database.","PeriodicalId":166633,"journal":{"name":"Proceedings of the 11th ACM on Asia Conference on Computer and Communications Security","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122299625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shweta Shinde, Zheng Leong Chua, Viswesh Narayanan, P. Saxena
New hardware primitives such as Intel SGX secure a user-level process in presence of an untrusted or compromised OS. Such "enclaved execution" systems are vulnerable to several side-channels, one of which is the page fault channel. In this paper, we show that the page fault side-channel has sufficient channel capacity to extract bits of encryption keys from commodity implementations of cryptographic routines in OpenSSL and Libgcrypt -- leaking 27% on average and up to 100% of the secret bits in many case-studies. To mitigate this, we propose a software-only defense that masks page fault patterns by determinising the program's memory access behavior. We show that such a technique can be built into a compiler, and implement it for a subset of C which is sufficient to handle the cryptographic routines we study. This defense when implemented generically can have significant overhead of up to 4000X, but with help of developer-assisted compiler optimizations, the overhead reduces to at most 29.22% in our case studies. Finally, we discuss scope for hardware-assisted defenses, and show one solution that can reduce overheads to 6.77% with support from hardware changes.
{"title":"Preventing Page Faults from Telling Your Secrets","authors":"Shweta Shinde, Zheng Leong Chua, Viswesh Narayanan, P. Saxena","doi":"10.1145/2897845.2897885","DOIUrl":"https://doi.org/10.1145/2897845.2897885","url":null,"abstract":"New hardware primitives such as Intel SGX secure a user-level process in presence of an untrusted or compromised OS. Such \"enclaved execution\" systems are vulnerable to several side-channels, one of which is the page fault channel. In this paper, we show that the page fault side-channel has sufficient channel capacity to extract bits of encryption keys from commodity implementations of cryptographic routines in OpenSSL and Libgcrypt -- leaking 27% on average and up to 100% of the secret bits in many case-studies. To mitigate this, we propose a software-only defense that masks page fault patterns by determinising the program's memory access behavior. We show that such a technique can be built into a compiler, and implement it for a subset of C which is sufficient to handle the cryptographic routines we study. This defense when implemented generically can have significant overhead of up to 4000X, but with help of developer-assisted compiler optimizations, the overhead reduces to at most 29.22% in our case studies. Finally, we discuss scope for hardware-assisted defenses, and show one solution that can reduce overheads to 6.77% with support from hardware changes.","PeriodicalId":166633,"journal":{"name":"Proceedings of the 11th ACM on Asia Conference on Computer and Communications Security","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131947232","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yu-Ming Ke, Chih-Wei Chen, H. Hsiao, A. Perrig, V. Sekar
This study stems from the premise that we need to break away from the "reactive" cycle of developing defenses against new DDoS attacks (e.g., amplification) by proactively investigating the potential for new types of DDoS attacks. Our specific focus is on pulsating attacks, a particularly debilitating type that has been hypothesized in the literature. In a pulsating attack, bots coordinate to generate intermittent pulses at target links to significantly reduce the throughput of TCP connections traversing the target. With pulsating attacks, attackers can cause significantly greater damage to legitimate users than traditional link flooding attacks. To date, however, pulsating attacks have been either deemed ineffective or easily defendable for two reasons: (1) they require a central coordinator and can thus be tracked; and (2) they require tight synchronization of pulses, which is difficult even in normal non-congestion scenarios. This paper argues that, in fact, the perceived drawbacks of pulsating attacks are in fact not fundamental. We develop a practical pulsating attack called CICADAS using two key ideas: using both (1) congestion as an implicit signal for decentralized implementation, and (2) a Kalman-filter-based approach to achieve tight synchronization. We validate CICADAS using simulations and wide-area experiments. We also discuss possible countermeasures against this attack.
{"title":"CICADAS: Congesting the Internet with Coordinated and Decentralized Pulsating Attacks","authors":"Yu-Ming Ke, Chih-Wei Chen, H. Hsiao, A. Perrig, V. Sekar","doi":"10.1145/2897845.2897866","DOIUrl":"https://doi.org/10.1145/2897845.2897866","url":null,"abstract":"This study stems from the premise that we need to break away from the \"reactive\" cycle of developing defenses against new DDoS attacks (e.g., amplification) by proactively investigating the potential for new types of DDoS attacks. Our specific focus is on pulsating attacks, a particularly debilitating type that has been hypothesized in the literature. In a pulsating attack, bots coordinate to generate intermittent pulses at target links to significantly reduce the throughput of TCP connections traversing the target. With pulsating attacks, attackers can cause significantly greater damage to legitimate users than traditional link flooding attacks. To date, however, pulsating attacks have been either deemed ineffective or easily defendable for two reasons: (1) they require a central coordinator and can thus be tracked; and (2) they require tight synchronization of pulses, which is difficult even in normal non-congestion scenarios. This paper argues that, in fact, the perceived drawbacks of pulsating attacks are in fact not fundamental. We develop a practical pulsating attack called CICADAS using two key ideas: using both (1) congestion as an implicit signal for decentralized implementation, and (2) a Kalman-filter-based approach to achieve tight synchronization. We validate CICADAS using simulations and wide-area experiments. We also discuss possible countermeasures against this attack.","PeriodicalId":166633,"journal":{"name":"Proceedings of the 11th ACM on Asia Conference on Computer and Communications Security","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122100026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cross-site scripting (XSS) attacks keep plaguing the Web. Supported by most modern browsers, Content Security Policy (CSP) prescribes the browser to restrict the features and communication capabilities of code on a web page, mitigating the effects of XSS. This paper puts a spotlight on the problem of data exfiltration in the face of CSP. We bring attention to the unsettling discord in the security community about the very goals of CSP when it comes to preventing data leaks. As consequences of this discord, we report on insecurities in the known protection mechanisms that are based on assumptions about CSP that turn out not to hold in practice. To illustrate the practical impact of the discord, we perform a systematic case study of data exfiltration via DNS prefetching and resource prefetching in the face of CSP. Our study of the popular browsers demonstrates that it is often possible to exfiltrate data by both resource prefetching and DNS prefetching in the face of CSP. Further, we perform a crawl of the top 10,000 Alexa domains to report on the cohabitance of CSP and prefetching in practice. Finally, we discuss directions to control data exfiltration and, for the case study, propose measures ranging from immediate fixes for the clients to prefetching-aware extensions of CSP.
{"title":"Data Exfiltration in the Face of CSP","authors":"S. Acker, Daniel Hausknecht, A. Sabelfeld","doi":"10.1145/2897845.2897899","DOIUrl":"https://doi.org/10.1145/2897845.2897899","url":null,"abstract":"Cross-site scripting (XSS) attacks keep plaguing the Web. Supported by most modern browsers, Content Security Policy (CSP) prescribes the browser to restrict the features and communication capabilities of code on a web page, mitigating the effects of XSS. This paper puts a spotlight on the problem of data exfiltration in the face of CSP. We bring attention to the unsettling discord in the security community about the very goals of CSP when it comes to preventing data leaks. As consequences of this discord, we report on insecurities in the known protection mechanisms that are based on assumptions about CSP that turn out not to hold in practice. To illustrate the practical impact of the discord, we perform a systematic case study of data exfiltration via DNS prefetching and resource prefetching in the face of CSP. Our study of the popular browsers demonstrates that it is often possible to exfiltrate data by both resource prefetching and DNS prefetching in the face of CSP. Further, we perform a crawl of the top 10,000 Alexa domains to report on the cohabitance of CSP and prefetching in practice. Finally, we discuss directions to control data exfiltration and, for the case study, propose measures ranging from immediate fixes for the clients to prefetching-aware extensions of CSP.","PeriodicalId":166633,"journal":{"name":"Proceedings of the 11th ACM on Asia Conference on Computer and Communications Security","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114639606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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