# 5G-Based Smart Healthcare and Mobile Network Security: Combating Fake Base Stations
## 3 Fake Base Stations
### Fake Base Station Attack  
Fake base stations, also known as rouge base stations, are malicious devices that impersonate authentic base stations. Their primary aim is to deceive the UE into connecting to unauthorized services and to potentially extract sensitive user information, such as IMSI data [9]. The presence of these \"IMSI-Catchers\" has been noted since the 2G era, posing a global concern with reports of suspicious devices appearing in major cities and instances of law enforcement using similar equipment for surveillance [10; 11]. And some security researchers have been working on the topic of 5G fake base stations [12]. A recent case in Taiwan involved the use of fake base stations for phishing attacks. The suspects acquired fake base stations from China, allowing them to transmit phishing SMS messages and to trick people into revealing their credit card information. The attackers achieved this by downgrading the victims' phones to 2G, disconnecting them from legitimate 4G/5G base stations, and making them vulnerable to phishing messages [3]. Similar cases have been observed in China, and [PERSON] et al. [13] made efforts to characterize these cases, providing insights into the fake base stations' spam ecosystem, which is operated by criminals or unscrupulous businesses. While recent cases have mainly used fake base stations for phishing attacks targeting credit card information, this demonstrates that fake base stations remain a relevant threat in modern 4G/5G mobile networks. Phishing messages can be easily modified to deceive unsuspecting victims into accessing fake websites, leading to potential privacy breaches and financial losses. A typical attack procedure using a fake BS attack is illustrated to help understand the attack. In the telecom sector, these activities represent a malicious sequence targeting mobile network vulnerabilities and compromising user security and privacy:  
Step 1. Setting up a fake base station:  
Malicious actors configure counterfeit hardware and software to mimic genuine base stations, deceiving the targeted cellular network. Step 2. Entering the target's radio range:  
The counterfeit base station is strategically positioned near the victim to lure their mobile device into connecting unwittingly. Step 3. Performing the desired attacks:  
Once the victim's mobile device connects to the spurious base station, attackers can execute a variety of malicious actions designed to compromise the integrity of the targeted network and to harvest sensitive information. These attacks may include the following methods:  
* Gathering IMSI and/or location information: Malicious actors exploit the connection to retrieve the IMSI of the victim's device, thereby acquiring a unique identifier associated with the subscriber. Additionally, they may obtain location information, potentially compromising the user's privacy. * Spam phishing or malicious SMS messages: Attackers leverage the connection to send unsolicited, deceptive, or malicious Short Message Service (SMS) messages to the victim's device. These messages often serve as vehicles for phishing attempts or the delivery of harmful payloads, with the aim of tricking or coercing the user into taking detrimental actions. * Sending fake reject messages, emergency warnings, etc. : Malicious operators can utilize the fraudulent base station to transmit fabricated network messages, such as fake reject messages or counterfeit emergency alerts. This manipulation can lead to service disruptions or, in the case of false emergency warnings, cause panic and confusion among the affected users. In summary, this orchestration of a fake base station, strategic placement, and ensuing attacks represents a malevolent intrusion in telecom, posing significant security and privacy risks to mobile network users. Advanced fake base stations are also capable of performing denial of service (DoS) and man in the middle (MitM) attacks.