Cell-site simulators, also referred to as False Base Stations (FBS) or Stingrays, are radio units that mimic actual cell websites so as 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. Lately, carriers have began reporting new varieties of abuse perpetrated with FBSs for the needs of monetary 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 instantly into smartphones. This technique to inject messages totally 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 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 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 world carriers use to confer 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 units to inject Smishing (SMS phishing) payloads into person units. Fraudsters usually do that by driving round with transportable FBS units, and there have even been reviews of fraudsters carrying these units of their backpacks.
The strategy is simple and replicates identified strategies to trick cellular units 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 system additionally exposes a faux 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 drive 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 selected service or community utilizing a cellular 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 tough 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 totally 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 official 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 insurance discover.
Though the kind of abuse carriers are uncovering not too long ago 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 be aware that customers are nonetheless susceptible to this kind of fraud so long as cellular units help 2G, whatever the standing of 2G of their native service.
Android protects customers from phishing and fraud
There are a selection of Android-only safety features that may considerably mitigate, or in some circumstances absolutely block, the impression of this kind of fraud.
Android 12 launched a person choice to disable 2G on the modem degree, 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 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 crucial for the 2G FBS to configure a null cipher (e.g. A5/0) so as to inject an SMS payload. This safety characteristic launched with Android 14 requires units 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 establish and block spam SMS messages. Further safety is offered by means of RCS for Enterprise, a characteristic that helps customers establish official 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, particularly Secure Searching and Google Play Defend. As a further layer of safety, Secure Searching 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 characteristic 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 cellular expertise. We’re consistently working to enhance our safety features and shield customers from phishing, fraud, and different threats.
Working with world carriers and different OEMs by means of the GSMA to help 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.
