Cell-site simulators, often known as False Base Stations (FBS) or Stingrays, are radio units that mimic actual cell websites as a way to lure cellular units to hook up with them. These units are generally used for safety and privateness assaults, akin to surveillance and interception of communications. In recent times, carriers have began reporting new sorts of abuse perpetrated with FBSs for the needs of monetary fraud.
Specifically, 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 immediately into smartphones. This methodology to inject messages totally bypasses the provider 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 nations.
GSMA’s Fraud and Safety Group (FASG) has developed a briefing paper for GSMA members to boost consciousness of SMS Blaster fraud and supply pointers and mitigation suggestions for carriers, OEMs and different stakeholders. The briefing paper, out there 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 world carriers use to check 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 person units. Fraudsters sometimes do that by driving round with moveable FBS units, and there have even been reviews of fraudsters carrying these units of their backpacks.
The strategy is easy and replicates identified methods to trick cellular units to an attacker-controlled 2G community. SMS Blasters expose a pretend LTE or 5G community which executes a single perform: downgrading the person’s connection to a legacy 2G protocol. The identical gadget 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 power connections to be unencrypted, which allows a whole Individual-in-the-Center (PitM) place to inject SMS payloads.
SMS Blasters are bought 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 cellular app. Customers also can 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 tough 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 totally bypasses the provider 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 seem like it’s coming from the legit SMS aggregator of a financial institution, for instance. In a latest assault that impacted a whole bunch of 1000’s 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’s precedent for using 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 this sort of fraud so long as cellular units assist 2G, whatever the standing of 2G of their native provider.
Android protects customers from phishing and fraud
There are a selection of Android-only security measures that may considerably mitigate, or in some instances absolutely block, the affect of this sort of fraud.
Android 12 launched a person choice to disable 2G on the modem stage, a function first adopted by Pixel. This selection, if used, utterly mitigates the chance from SMS Blasters. This function has been out there since Android 12 and requires units 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 obligatory for the 2G FBS to configure a null cipher (e.g. A5/0) as a way to inject an SMS payload. This safety function launched with Android 14 requires units 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. Extra safety is supplied by way of RCS for Enterprise, a function that helps customers determine legit 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, specifically Protected Shopping and Google Play Defend. As a further layer of safety, Protected Shopping built-in on Android units protects 5 billion units globally and helps warn the customers about probably 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 comprises 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 protected and safe cellular expertise. We’re consistently working to enhance our security measures and shield customers from phishing, fraud, and different threats.
Working with world carriers and different OEMs by way of 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 stay up for partnering with ecosystem companions in additional elevating the safety bar on this house 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 put up: Yomna Nasser, Gil Cukierman, Il-Sung Lee, Eugene Liderman, Siddarth Pandit.