Instruct: Given a question, retrieve relevant passages that can help answer the question.
Query: What does "IMSI" stand for in IMSI-catcher?
An international mobile subscriber identity-catcher, or IMSI-catcher, is a telephone eavesdropping device used for intercepting mobile phone traffic and tracking location data of mobile phone users.[1] Essentially a "fake" mobile tower acting between the target mobile phone and the service provider's real towers, it is an example of a man-in-the-middle (MITM) attack. The 3G wireless standard offers some risk mitigation due to mutual authentication required from both the handset and the network.[2] However, sophisticated attacks may be able to downgrade 3G and LTE to non-LTE network services which do not require mutual authentication.[3]
For the system to work, both users must have crypto phones logged into crypto mode. As with other phones, the signal is encrypted by GSM but it is also encrypted by the cryptographic chip. When the IMSI-catcher performs a man-in-the-middle attack and disables the GSM encryption, the crypto phone encryption remains intact. Therefore, while the signal is still being intercepted, it can no longer be decoded and fake SMS messages can't be sent as the IMSI-catcher does not have the correct code.
The assignment of an IMSI catcher has a number of difficulties:
IMSI S – Short IMSI, Mobile Identification Number
In 2006, IMSI/Design, LLC was spun out of IMSI, which had just been renamed 'Broadcaster, Inc', as part of a management buy-out of the TurboCAD product line, several other IMSI products and the IMSI name. The spin-out was led by Royal Farros, Bob Mayer and Greyhawk Capital Management The same Russian development team however continued to work of the TurboCAD code.
IMSI may refer to:
The device is similar to but distinct from an IMSI catcher.
To the mobile phones in its vicinity, a device called an "IMSI-catcher" pretends to be a legitimate base station of the mobile phone network, thus subjecting the communication between the phone and the network to a man-in-the-middle attack. This is possible because, while the mobile phone has to authenticate itself to the mobile telephone network, the network does not authenticate itself to the phone. There is no defense against IMSI-catcher based eavesdropping, except using end-to-end call encryption; products offering this feature, secure telephones, are already beginning to appear on the market, though they tend to be expensive and incompatible with each other, which limits their proliferation.
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.[7] 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.[8] 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.
Some preliminary research has been done in trying to detect and frustrate IMSI-catchers. One such project is through the Osmocom open source mobile station software. This is a special type of mobile phone firmware that can be used to detect and fingerprint certain network characteristics of IMSI-catchers, and warn the user that there is such a device operating in their area. But this firmware/software-based detection is strongly limited to a select few, outdated GSM mobile phones (i.e. Motorola) that are no longer available on the open market. The main problem is the closed-source nature of the major mobile phone producers.
At power-down the MS requests a signaling channel.
Once assigned, the MS sends an IMSI detach message to the VLR.
When the VLR receives the IMSI detach-message, the corresponding IMSI is marked as detached by setting the IMSI detach flag. The HLR is not informed of this and the VLR does not acknowledge the MS about the IMSI detach.
If the radio link quality is poor when IMSI detach occurs, the VLR may not properly receive the IMSI-detach request. Since an acknowledgment message is not sent to the MS, it does not make further attempts to send IMSI detach messages. Therefore, the GSM network considers the MS to be still attached.
The application Android IMSI-Catcher Detector (AIMSICD) is being developed to detect and circumvent IMSI-catchers, StingRay and silent SMS.[19] Technology for a stationary network of IMSI-catcher detectors has also been developed.[7] Several apps listed on the Google Play Store as IMSI catcher detector apps include SnoopSnitch, Cell Spy Catcher, and GSM Spy Finder and have between 100,000 and 500,000 app downloads each. However, these apps have limitations in that they do not have access to phone's underlying hardware and may offer only minimal protection.[20]
IMSI analysis is the process of examining a subscriber's IMSI to identify the network the IMSI belongs to, and whether subscribers from that network may use a given network (if they are not local subscribers, this requires a roaming agreement). 
In 1993, IMSI began to outsource the development of TurboCAD. After a trip to Russia by Martin Sacks, IMSI hired 3 Russian programmers who began work on TurboCAD Windows v2. Included in these 3 original hires were Victor Bazarov, who later came to work in San Rafael for IMSI and Alex Presniak who went on to start SoftDev on behalf of IMSI.
The IMSI-catcher subjects the phones in its vicinity to a man-in-the-middle attack, appearing to them as a preferred base station in terms of signal strength. With the help of a SIM, it simultaneously logs into the GSM network as a mobile station. Since the encryption mode is chosen by the base station, the IMSI-catcher can induce the mobile station to use no encryption at all. Hence it can encrypt the plain text traffic from the mobile station and pass it to the base station.
There is only an indirect connection from mobile station via IMSI-catcher to the GSM network. For this reason, incoming phone calls cannot generally be patched through to the mobile station by the GSM network, although more modern versions of these devices have their own mobile patch-through solutions in order to provide this functionality.
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.[10] They can also be used in search and rescue operation for missing persons.[11] Police departments have been reluctant to reveal use of these programs and contracts with vendors such as Harris Corporation, the maker of Stingray and Kingfish phone tracker devices.[12]
Telephone tapping Stingray phone tracker Mobile phone jammer
Interface:2010 is The Interface Marketing Supplier Integration Institute, widely known as INTERFACE and IMSI, is an international-standard-setting body composed of representatives from various national marketing and supply chain management organizations. Founded on 11 March 2009, the organization promulgates worldwide proprietary marketing supplier integration standards. It is headquartered in Geneva, Switzerland. While IMSI defines itself as a non-governmental organization, its ability to improve the marketing supply chain, reduce costs and eliminate risk makes the IMSI highly influential within the government sector.
The device is described as in size. To mimic a cell phone tower, it utilizes IMSI-catcher (International Mobile Subscriber Identity) technology, which phone services use to identify individual subscribers. It emits a pilot signal made to appear stronger than that from the nearest cell tower, causing phones within its range to broadcast their IMSI numbers and electronic serial numbers (ESN). Encryption does not prevent this process; the devices can retrieve a phone's encryption session keys in less than one second, with success rates of 50–75% under "real world conditions".
A virtual base transceiver station (VBTS)[5] is a device for identifying the international mobile subscriber identity (IMSI) of a nearby GSM mobile phone and intercepting its calls. It was patented[5] and first commercialized by Rohde & Schwarz in 2003. The device can be viewed as simply a modified cell tower with a malicious operator, and on 4 January 2012, the Court of Appeal of England and Wales held that the patent is invalid for obviousness.[6]
In the UK, the first public body to admit using IMSI catchers was the Scottish Prison Service,[13] though it is likely that the Metropolitan Police Service has been using IMSI catchers since 2011 or before.[14]
A comparatively new off-the-shelf surveillance device is an IMSI-catcher, a telephone eavesdropping device used to intercept mobile phone traffic and track the movement of mobile phone users. Essentially a "fake" mobile tower acting between the target mobile phone 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.
The MSISDN together with IMSI are two important numbers used for identifying a mobile subscriber. The latter is stored in the SIM, i.e. the card inserted into the mobile phone, and each IMSI uniquely identifies the mobile station, its home wireless network, and the home country of the home wireless network, while the former is the number used for routing calls to the subscriber. IMSI is often used as a key in the HLR ("subscriber database") and MSISDN is the number normally dialed to connect a call to the mobile phone. A SIM has a unique IMSI that does not change, while the MSISDN can change in time, i.e. different MSISDNs can be associated with the SIM.
Body-worn IMSI-catchers that target nearby mobile phones are being advertised to law enforcement agencies in the US.[9]