著者

Satomi Saito Koji Maruhashi Masahiko Takenaka Satoru Torii

出版者

一般社団法人 情報処理学会

雑誌

Journal of Information Processing (ISSN:18826652)

巻号頁・発行日

vol.24, no.2, pp.217-226, 2016 (Released:2016-03-15)

参考文献数

27

被引用文献数

7

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Brute force attacks are used to obtain pairs of user names and passwords illegally by using all existing pairs to login to network services. These are a major security threat faced by network service administrators. In general, to prevent brute force attacks, administrators can set limitations on the number of login trials and shut down the traffic of brute force attacks with an intrusion prevention system (IPS) at the entry point to their services. In recent years, stealthy brute force attacks that can avoid the security rules and IPS and intrusion detection system (IDS) detection have appeared. Attackers tend to arrange a large amount of hosts and allocate them fewer login trials than the limitations administrators set. In this paper, we report a kind of distributed brute force attack event (brute force attacks with disciplined IPs, or DBF) against the Remote Desktop Protocol (RDP) by analyzing IDS logs integrated from multiple sites. In DBF, a particular number of attacks is repeated automatically from a host to a service over a period. For this reason, existing countermeasures have no effect on DBF. We investigate the structure of DBF and improve the existing countermeasure system. We also present TOPASE, which is replaced at each step of the existing countermeasure system and is suitable for DBF countermeasures. TOPASE analyzes the regularity of login trials between a source host and a destination host. Furthermore, TOPASE intercepts the network traffic from the source host of the brute force attack for a specific period. As a result of the evaluation with our IDS log, we estimate the performance of TOPASE and clarify the factors that maximize TOPASE's effectiveness.

著者

Masahiko TAKENAKA Kazuaki TAKASHIMA Hajimu KURUMATANI Nobutaka IDA Reeko SATO Yoshihisa YAMANE

出版者

動物臨床医学会

雑誌

動物臨床医学 (ISSN:13446991)

巻号頁・発行日

vol.20, no.4, pp.131-139, 2011-12-31 (Released:2012-12-18)

参考文献数

30

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Objective : Since the sensitivity to prostacyclin differs widely depending on the animal species, it is essential to investigate the dose setting from the safety point of view before using beraprost (BPS) in diseased cats.Design : One week multiple administration toxicity study of BPS (10, 30, 70, 100 μg/kg, twice a day) compared with vehicle as control.Procedure : BPS group (n=6) at 10, 30, 70 and 100 μg/kg and vehicle group (n=5) were administered to healthy cats twice a day for 7 days. Both in BPS and vehicle groups, cessation period of the drug was provided 2 weeks between each doses of BPS. In addition hemodynamic parameters were also noted at 0.5 hour before initial administration on the first day and at 1 hour after final administration on the 7th day of each dose of BPS and vehicle.Results : Though BPS from 30 μg/kg upward transiently and dose-dependently increased the heart rate but had no influence on the blood pressure. Compared with the vehicle group, serum creatinine slightly but significantly decreased at 70 and 100 μg/kg and this decrease was also significant against the pre-administration value at the same dose. The influence of BPS on the blood parameters was nil or negligible, if any. Diarrhea were sporadically noted at 70 μg/kg, and mild and transient vomiting and sedation occurred at 100 μg/kg. However, each symptom soonerly disappeared without treatment.Conclusion : The pharmacological action and types of adverse effects of BPS in the cats were almost similar to those observed in other animals and the repeated oral administration of BPS can be safely conducted in cats at least up to 30 μg/kg twice a day.