SIM Farms

A UK government consultation paper of May 2023 proposes to ban the manufacture, import, sale, hire, possession and/or use of SIM farms regardless of what they might be used for.

A SIM Farm or SIM Box is a device that holds multiple SIM Cards allowing numerous SMS messages to be sent in a very short time.  These devices are currently legal in the UK.  An example 32-port 4G compatible device being advertised on Ali Express for £1,712.  There will also be software costs and no guarantee that this particular device will work with modern software and hardware.  Doubtless the enterprising criminal buyer will do their homework to ensure a functioning set up.  A raid by Ukrainian police in December 2022 shows racks of SIM Boxes supporting 500 or more individual cards.  In this case the farm was allegedly being used to distribute propaganda supporting the Russian invasion of Ukraine.  The UK government does not see a need for SIM Boxes supporting more than 4 separate SIM cards, one for each mobile network operating in the UK.

SIM Boxes facilitate the relatively simplistic attacks that target a large number of individuals in the hope of finding a willing mark.  SMS scams could include a link to a compromised website that installs malware.  Smishing attacks might harvest personal information or be the beginning of a chain leading to financial fraud.   Kindus discussed the medium of SMS for fake delivery scams in 2022.  A Guardian report of April 2023 alleges that it is the immediacy of text messages and the ease with which they can be picked up and responded to that makes them a better medium for scams than email messages.  The text of a message itself cannot do any harm (besides time wasting and annoyance) as long as the recipient does not interact with or reply to it.  UK government advice is that any suspect text should be forwarded to 7726.

The advantage to the fraudster of the SIM Box is that any fraud will be traced back to the SIM cards on the farm.  These will have been obtained cheaply or stolen and are linked to the SIM card network provider who in turn is unlikely to have a genuine contract with the sender.  SIM Farm operations are often set up in countries where texts are free or at a low cost further reducing running costs for the scam.   SIM Boxes can be supported by technology that mimics the behaviour of human operated devices such as the provision for SIM cards in the farm to text each other; reducing the capability of network providers to block them.

There is also a legal if sneaky use of SIM Boxes to send multiple texts.  This is in the field of marketing and business communications where a body wants to send text messages to large numbers of legitimate contacts.   Uses could include marketing, competitions, delivery notifications and appointment reminders.  Data networks prefer that such bodies make use of their A2P (Application to Person) services.  These will read data directly from a database and handle the individual replies at great speed.  Emitrr quote A2P message rates of 4,500 per minute and up to 200,000 messages per day.  The global business spending on A2P in 2022 is claimed to be $(US)32 Billion.  Although dedicated messaging systems such as WhatsApp are cutting into the SMS market share the SIM Box software can be used to send bulk messages to these and social media platforms as well.  The SIM Farm approach is cheaper than A2P and could be used to avoid legislation such as GDPR because the source is harder to regulate.  The nature of the SIM Box traffic is also less optimised than through A2P so large volumes of transmissions are more likely to slow down the data network.

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