Cell-site simulators, often known as False Base Stations (FBS) or Stingrays, are radio gadgets that mimic actual cell websites as a way to lure cellular gadgets to connect with them. These gadgets are generally used for safety and privateness assaults, akin to surveillance and interception of communications. Lately, carriers have began reporting new forms of abuse perpetrated with FBSs for the needs of economic fraud.
Particularly, there’s more and more extra proof of the exploitation of weaknesses in mobile communication requirements leveraging cell-site simulators to inject SMS phishing messages straight into smartphones. This technique to inject messages fully bypasses the service community, thus bypassing all the subtle network-based anti-spam and anti-fraud filters. Cases of this new kind of fraud, which carriers check with as SMS Blaster fraud, have been reported in Vietnam, France, Norway, Thailand and a number of different international locations.
GSMA’s Fraud and Safety Group (FASG) has developed a briefing paper for GSMA members to lift consciousness of SMS Blaster fraud and supply tips and mitigation suggestions for carriers, OEMs and different stakeholders. The briefing paper, obtainable for GSMA members solely, calls out some Android-specific suggestions and options that may assist successfully shield our customers from this new kind of fraud.
What are SMS Blasters?
SMS Blaster is the time period that international carriers use to check with FBS and cell-site simulators operated unlawfully with the purpose of disseminating (blast) SMS payloads. The most typical use case is to leverage these gadgets to inject Smishing (SMS phishing) payloads into person gadgets. Fraudsters sometimes do that by driving round with moveable FBS gadgets, and there have even been studies of fraudsters carrying these gadgets of their backpacks.
The tactic is easy and replicates identified methods to trick cellular gadgets to an attacker-controlled 2G community. SMS Blasters expose a pretend LTE or 5G community which executes a single operate: downgrading the person’s connection to a legacy 2G protocol. The identical gadget additionally exposes a pretend 2G community, which lures all of the gadgets to connect with it. At this level, attackers abuse the well-known lack of mutual authentication in 2G and drive connections to be unencrypted, which allows an entire Individual-in-the-Center (PitM) place to inject SMS payloads.
SMS Blasters are offered on the web and don’t require deep technical experience. They’re easy to arrange and able to function, and customers can simply configure them to mimic a specific service or community utilizing a cellular app. Customers may simply configure and customise the SMS payload in addition to its metadata, together with for instance the sender quantity.
SMS Blasters are very interesting to fraudsters given their nice return on funding. Spreading SMS phishing messages generally yields a small return as it is vitally troublesome to get these messages to fly undetected by refined anti-spam filters. A really small subset of messages ultimately attain a sufferer. In distinction, injecting messages with an SMS blaster fully bypasses the service community and its anti-fraud and anti-spam filters, guaranteeing that every one messages will attain a sufferer. Furthermore, utilizing an FBS the fraudster can management all fields of the message. One could make the message appear like it’s coming from the reputable SMS aggregator of a financial institution, for instance. In a latest assault that impacted lots of of hundreds of gadgets, the messages masqueraded as a medical insurance discover.
Though the kind of abuse carriers are uncovering just lately is monetary fraud, there’s precedent for the usage of rogue mobile base stations to disseminate malware, for instance injecting phishing messages with a url to obtain the payload. You will need to observe that customers are nonetheless susceptible to one of these fraud so long as cellular gadgets assist 2G, whatever the standing of 2G of their native service.
Android protects customers from phishing and fraud
There are a selection of Android-only security measures that may considerably mitigate, or in some circumstances absolutely block, the impression of one of these fraud.
Android 12 launched a person choice to disable 2G on the modem stage, a characteristic first adopted by Pixel. This feature, if used, utterly mitigates the chance from SMS Blasters. This characteristic has been obtainable since Android 12 and requires gadgets to adapt to Radio HAL 1.6+.
Android additionally has an choice to disable null ciphers as a key safety as a result of it’s strictly mandatory for the 2G FBS to configure a null cipher (e.g. A5/0) as a way to inject an SMS payload. This safety characteristic launched with Android 14 requires gadgets that implement radio HAL 2.0 or above.
Android additionally offers efficient protections that particularly tackles SMS spam and phishing, no matter whether or not the supply channel is an SMS Blaster. Android has built-in spam safety that helps to determine and block spam SMS messages. Further safety is supplied by RCS for Enterprise, a characteristic that helps customers determine reputable SMS messages from companies. RCS for Enterprise messages are marked with a blue checkmark, which signifies that the message has been verified by Google.
We advocate leveraging a few vital Google security measures which can be found on Android, particularly Secure Searching and Google Play Shield. As a further layer of safety, Secure Searching built-in on Android gadgets protects 5 billion gadgets globally and helps warn the customers about doubtlessly dangerous websites, downloads and extensions which may very well be phishing and malware-based.
Let’s say a person decides to obtain an app from the Play retailer however the app accommodates code that’s malicious or dangerous, customers are protected by Google Play Shield which is a safety characteristic that scans apps for malware and different threats. It additionally warns customers about doubtlessly dangerous apps earlier than they’re put in.
Android’s dedication to safety and privateness
Android is dedicated to offering customers with a protected and safe cellular expertise. We’re continually working to enhance our security measures and shield customers from phishing, fraud, and different threats.
Working with international carriers and different OEMs by the GSMA to assist the ecosystem within the growth and adoption of additional mobile safety and privateness options is a precedence space for Android. We look ahead to partnering with ecosystem companions in additional elevating the safety bar on this area to guard cellular customers from threats like SMS blasters.
Thanks to all our colleagues who actively contribute to Android’s efforts in tackling fraud and FBS threats, and particular due to those that contributed to this weblog submit: Yomna Nasser, Gil Cukierman, Il-Sung Lee, Eugene Liderman, Siddarth Pandit.