Cell-site simulators, also called False Base Stations (FBS) or Stingrays, are radio gadgets that mimic actual cell websites as a way to lure cell gadgets to hook up with them. These gadgets are generally used for safety and privateness assaults, comparable to surveillance and interception of communications. Lately, carriers have began reporting new kinds of abuse perpetrated with FBSs for the needs of monetary fraud.
Specifically, 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 completely bypasses the provider community, thus bypassing all the delicate network-based anti-spam and anti-fraud filters. Situations 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 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 check with FBS and cell-site simulators operated unlawfully with the aim of disseminating (blast) SMS payloads. The commonest use case is to leverage these gadgets to inject Smishing (SMS phishing) payloads into person gadgets. Fraudsters sometimes do that by driving round with transportable FBS gadgets, and there have even been reviews of fraudsters carrying these gadgets of their backpacks.
The tactic is easy and replicates identified methods to trick cell gadgets to an attacker-controlled 2G community. SMS Blasters expose a faux 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 faux 2G community, which lures all of the gadgets to hook up with it. At this level, attackers abuse the well-known lack of mutual authentication in 2G and drive connections to be unencrypted, which permits a whole Particular person-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 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 rather 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 completely 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 appear to be it’s coming from the authentic SMS aggregator of a financial institution, for instance. In a latest assault that impacted tons of of hundreds of gadgets, the messages masqueraded as a medical health insurance discover.
Though the kind of abuse carriers are uncovering just lately is monetary fraud, there may be precedent for using rogue mobile base stations to disseminate malware, for instance injecting phishing messages with a url to obtain the payload. It is very important be aware that customers are nonetheless weak to the sort of fraud so long as cell gadgets help 2G, whatever the standing of 2G of their native provider.
Android protects customers from phishing and fraud
There are a selection of Android-only safety features that may considerably mitigate, or in some instances totally block, the impression of the sort of fraud.
Android 12 launched a person choice to disable 2G on the modem degree, 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 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 function launched with Android 14 requires gadgets that implement radio HAL 2.0 or above.
Android additionally supplies 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 means of RCS for Enterprise, a function that helps customers determine authentic 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 essential Google safety features which can be found on Android, particularly Protected Looking and Google Play Defend. As an extra layer of safety, Protected Looking 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 incorporates 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 doubtlessly 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 continuously working to enhance our safety features and defend customers from phishing, fraud, and different threats.
Working with international carriers and different OEMs by means of the GSMA to help the ecosystem within the improvement 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 house 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.
