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An IMSI-catcher (International Mobile Subscriber Identity) is a telephony eavesdropping device used for intercepting mobile phone traffic and tracking movement of mobile phone users. Essentially a "fake" mobile tower acting between the target mobile phone(s) and the service provider's real towers, it is considered a man-in-the-middle (MITM) attack. IMSI-catchers are used in some countries by law enforcement and intelligence agencies, but their use has raised significant civil liberty and privacy concerns and is strictly regulated in some countries such as under the German Code of Criminal Procedure (StPO). Some countries do not even have encrypted phone data traffic (or very weak encryption), thus rendering an IMSI-catcher unnecessary. ==Overview== A virtual base transceiver station (VBTS) is a device for identifying the International Mobile Subscriber Identity (IMSI) of a nearby GSM mobile phone and intercepting its calls. It was patented〔 and first commercialized by Rohde & Schwarz in 2003, although it would be hard to maintain such a patent, since in reality it is just a modified cell tower with a malicious operator. On 24 January 2012, the Court of Appeal of England and Wales held that the patent is invalid for obviousness.〔(MMI Research Ltd v Cellxion Ltd & Ors [2012] EWCA Civ 7 (24 January 2012) ), Court of Appeal judgment invalidating Rohde & Schwarz patent.〕 The GSM specification requires the handset to authenticate to the network, but does ''not'' require the network to authenticate to the handset. This well-known security hole is exploited by an IMSI catcher. The IMSI catcher masquerades as a base station and logs the IMSI numbers of all the mobile stations in the area, as they attempt to attach to the IMSI-catcher.〔(【引用サイトリンク】title=The Spyware That Enables Mobile-Phone Snooping )〕 It allows forcing the mobile phone connected to it to use no call encryption (A5/0 mode) or to use easily breakable encryption (A5/1 or A5/2 mode), making the call data easy to intercept and convert to audio. Body-worn IMSI-catchers that target nearby mobile phones are being advertised to law enforcement agencies in the US.〔(【引用サイトリンク】title=The body-worn "IMSI catcher" for all your covert phone snooping needs )〕 IMSI-catchers are often deployed by court order without a search warrant, the lower judicial standard of a pen register and trap-and-trace order being preferred by law enforcement.〔(/2015/04/county-prosecutor-says-it-has-no-idea-when-stingrays-were-used-so-man-sues/ )〕 They can also be used in search and rescue operation for missing persons. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「IMSI-catcher」の詳細全文を読む スポンサード リンク
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