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Objective:Several published studies have investigated the association between the −308G/A (rs1800629) polymorphism in the tumor necrosis factor-α (TNF-α) gene and the risk of dilated cardiomyopathy (DCM). However, the TNF-α gene polymorphism has a controversial role in the pathogenesis of DCM among different populations. In the present study, a meta-analysis was performed to resolve this inconsistency.Methods:Potentially eligible papers reporting an association between the TNF-α rs1800629 polymorphism and DCM susceptibility were searched in 4 databases including PubMed, EMBASE, Chinese Biomedical Database (CBM), and the Cochrane Library up to April 1, 2018. The odds ratio (OR) with its 95% confidence interval (CI) was used to estimate the strength of the associations. Subgroup analysis based on the ethnicity, studies with or without ischemic and valvular DCM was conducted. Publication bias detection was conducted using Begg test.Results:Nine papers detailing case-control studies were included, reporting a total of 1339 DCM cases and 1677 healthy controls. The meta-analysis results indicated that TNF-α rs1800629 was associated with increased DCM susceptibility in the populations studied under the heterozygous model (AG vs GG: OR = 1.91, 95% CI = 1.05−3.50, P = .035) and dominant model (AG + AA vs GG: OR = 1.87, 95% CI = 1.01−3.45, P = .046). In the subgroup analysis for ethnicity, rs1800629 polymorphism was significantly associated with the susceptibility of DCM for Asians under the 5 models (A vs G: OR = 2.87, 95% CI = 1.56−5.30, P = .001; AA vs GG: OR = 3.95, 95% CI = 1.13−13.82, P = 0.031; AG vs GG: OR = 3.8, 95% CI = 1.57−9.19, P = .003; AA vs GG + AG: OR = 2.51, 95% CI = 1.41−4.49, P = .002; AG + AA vs GG: OR = 3.77, 95% CI = 1.54−9.20, P = .004).Conclusion:There may be a moderate association between TNF-α rs1800629 polymorphism and DCM susceptibility in the whole populations studied; however, TNF-α rs1800629 polymorphism was significantly associated with the susceptibility of DCM for Asians, which indicates that such associations may be different between ethnicities.

Today peer-to-peer (P2P) file sharing networks help tens of millions of users to share contents on the Internet. However, users' private files in their shared folders might become accessible to everybody inadvertently. In this paper, we investigate this kind of user privacy exposures in Kad, one of the biggest P2P file sharing networks, and try to answer two questions: Q1. Whether and to what extent does this problem exist in current systems? Q2. Are attackers aware of this privacy vulnerability and are they abusing obtained private information?We build a monitoring system called Dragonfly based on the eclipse mechanism to passively monitor sharing and downloading events in Kad. We also use the Honeyfile approach to share forged private information to observe attackers' behaviors. Based on Dragonfly and Honeyfiles, we give affirmative answers to the above two questions. Within two weeks, more than five thousand private files related to ten sensitive keywords were shared by Kad users, and over half of them come from Italy and Spain. Within one month, each honey file was downloaded for about 40 times in average, and its inner password information was exploited for 25 times. These results show that this privacy problem has become a serious threat for P2P users. Finally, we design and implement Numen, a plug-in for eMule, which can effectively protect user private files from being shared without notice.

Distributed reflective denial of service (DRDoS) attacks, especially those based on UDP reflection and amplification, can generate hundreds of gigabits per second of attack traffic, and have become a significant threat to Internet security. In this paper we show that an attacker can further make the DRDoS attack more dangerous. In particular, we describe a new DRDoS attack called store-and-flood DRDoS, or SF-DRDoS. By leveraging peerto-peer (P2P) file-sharing networks, SF-DRDoS becomes more surreptitious and powerful than traditional DRDoS. An attacker can store carefully prepared data on reflector nodes before the flooding phase to greatly increase the amplification factor of an attack. We implemented a prototype of SF-DRDoS on Kad, a popular Kademlia-based P2P file-sharing network. With realworld experiments, this attack achieved an amplification factor of 2400 on average, with the upper bound of attack bandwidth at 670 Gbps in Kad. Finally, we discuss possible defenses to mitigate the threat of SF-DRDoS.

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