#头条首发大赛#
Quick guide
SMS senders, also known as fake base stations or cell simulators, are a potential cyberattack tool that can be used by malicious users to trick mobile devices into connecting and sending fraudulent text messages. To combat this threat, users are advised to disable the 2G connection on their Android devices. The Global System for Mobile Communications Association (GSMA) has published a dedicated briefing to help members identify and respond to the risks posed by SMS senders. This type of attack usually involves forging the sender's number, spreading malware, and committing financial fraud. Android has offered the option to disable 2G since version 12, and Pixel phones are the first devices to implement this feature. In addition, Android 14 introduces the option to disable empty passwords to prevent SMS senders from injecting malicious payloads. The Google Messages app also has the ability to identify and block spam text messages, enhancing the user's security.
Understand SMS senders and their risks
SMS senders, also known as assassins, fake base stations (FBS), and base station simulators, can be exploited by malicious individuals to trick mobile devices into connecting with them and subsequently sending fraudulent text messages. One of the ways to effectively combat this threat is to disable the insecure 2G connection on your Android device. The Global System for Mobile Communications Association (GSMA)'s Fraud & Security Group (FASG) has prepared a briefing note specifically for GSMA members to raise awareness of SMS sender fraud and provide guidance and mitigation strategies to operators, OEMs and other relevant stakeholders. This GSMA members-only document highlights certain Android-specific recommendations and features that can significantly help users defend against this emerging form of fraud.
The essence of an SMS sender attack
Fraudulent messages generated by SMS senders are transmitted only over 2G networks, often leading to financial fraud, and the number of reported incidents worldwide has increased in recent years. Attackers can easily spoof the sender's number to make the message appear to come from a legitimate business. In addition, there have been cases where these devices have been used to spread malware, such as injecting phishing messages containing the download of malicious payloads. SMS transmitters create a fake LTE or 5G network with the sole purpose of downgrading the user's connection to the fragile 2G protocol. In addition, they offer a fake 2G network that tricks devices into connecting, and in the process, attackers take advantage of the notoriously unauthenticated features of 2G to result in an unencrypted connection, enabling a complete man-in-the-middle attack (PitM) that injects harmful SMS payloads.
Take advantage of Android features to reduce risk
These portable text message senders are ubiquitous on the web and do not require extensive technical knowledge to operate and locate. Unlike traditional smishing tactics that rely on mass text messaging, this straightforward approach "bypasses the carrier network and its anti-fraud and anti-spam filters, ensuring that all messages reach their destination." "Since Android 12, Google has given users the option to disable 2G, and Pixel phones are the first to implement this feature. Even if "Allow 2G" is turned off, users can still make emergency calls. Effective use of this option completely eliminates the risks posed by SMS senders, and since Android 12 it has been implemented requiring devices to comply with Radio HAL 1.6 or newer. Users can find the "Allow 2G" option in the settings app of their Pixel device.
In addition, Android also provides the option to disable empty passwords, which is crucial because 2G FBS must be configured with an empty password (e.g., A5/0) to inject the SMS payload. This particular security feature was introduced in Android 14 and requires the device to support Radio HAL 2.0 or later. Another protection offered by Android is through Google Messages, which identifies and blocks spam text messages. In addition, Android offers strong protection against SMS spam and phishing, regardless of whether the delivery channel involves an SMS sender or not. Google has also introduced verified text messaging (ticked in blue in conversations) for business communications, as well as Safe Browsing and Play Protection to enhance user security.