Cell-site simulators, often known as False Base Stations (FBS) or Stingrays, are radio units that mimic actual cell websites with a view to lure cell units to hook up with them. These units are generally used for safety and privateness assaults, equivalent to surveillance and interception of communications. Lately, carriers have began reporting new sorts of abuse perpetrated with FBSs for the needs of monetary fraud.
Particularly, there may be more and more extra proof of the exploitation of weaknesses in mobile communication requirements leveraging cell-site simulators to inject SMS phishing messages immediately into smartphones. This technique to inject messages fully bypasses the provider community, thus bypassing all the subtle network-based anti-spam and anti-fraud filters. Situations of this new kind of fraud, which carriers confer 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 pointers 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 defend our customers from this new kind of fraud.
What are SMS Blasters?
SMS Blaster is the time period that international carriers use to confer with FBS and cell-site simulators operated unlawfully with the aim of disseminating (blast) SMS payloads. The most typical use case is to leverage these units to inject Smishing (SMS phishing) payloads into consumer units. Fraudsters usually do that by driving round with moveable FBS units, and there have even been studies of fraudsters carrying these units of their backpacks.
The tactic is easy and replicates recognized methods to trick cell units to an attacker-controlled 2G community. SMS Blasters expose a pretend LTE or 5G community which executes a single operate: downgrading the consumer’s connection to a legacy 2G protocol. The identical machine additionally exposes a pretend 2G community, which lures all of the units to hook up with it. At this level, attackers abuse the well-known lack of mutual authentication in 2G and pressure connections to be unencrypted, which allows an entire Particular person-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 provider or community utilizing a cell app. Customers can even 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 subtle anti-spam filters. A really small subset of messages finally attain a sufferer. In distinction, injecting messages with an SMS blaster fully bypasses the provider community and its anti-fraud and anti-spam filters, guaranteeing that each 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 current assault that impacted a whole bunch of hundreds of units, the messages masqueraded as a medical health insurance discover.
Though the kind of abuse carriers are uncovering not too long ago is monetary fraud, there may be 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 notice that customers are nonetheless weak to this kind of fraud so long as cell units assist 2G, whatever the standing of 2G of their native provider.
Android protects customers from phishing and fraud
There are a variety of Android-only safety features that may considerably mitigate, or in some circumstances totally block, the affect of this kind of fraud.
Android 12 launched a consumer choice to disable 2G on the modem stage, a function first adopted by Pixel. This selection, if used, fully mitigates the chance from SMS Blasters. This function has been obtainable since Android 12 and requires units to evolve 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 essential for the 2G FBS to configure a null cipher (e.g. A5/0) with a view to inject an SMS payload. This safety function launched with Android 14 requires units that implement radio HAL 2.0 or above.
Android additionally gives 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 establish and block spam SMS messages. Further safety is supplied by RCS for Enterprise, a function that helps customers establish 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 necessary Google safety features which can be found on Android, specifically Secure Shopping and Google Play Defend. As a further layer of safety, Secure Shopping built-in on Android units protects 5 billion units globally and helps warn the customers about probably dangerous websites, downloads and extensions which might be phishing and malware-based.
Let’s say a consumer 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 Defend which is a safety function that scans apps for malware and different threats. It additionally warns customers about probably dangerous apps earlier than they’re put in.
Android’s dedication to safety and privateness
Android is dedicated to offering customers with a secure and safe cell expertise. We’re always working to enhance our safety features and defend 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 sit up for partnering with ecosystem companions in additional elevating the safety bar on this area to guard cell 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 because of those that contributed to this weblog put up: Yomna Nasser, Gil Cukierman, Il-Sung Lee, Eugene Liderman, Siddarth Pandit.
