12.2.1 Physical Threats

Mobile devices have become common for computing and communication requirements among people because of their portable dimensions and high computing potentials. Due to these features, these gadgets are valuable and demand precautions for their physical security. In addition to the costly hardware that can be resold on the black market of gadgets, the information relevant to a user or organization can also be highly sensitive and worth far more. Due to these factors, stolen and lost mobile devices are one of those most frightening security threats. In terms of threats to physical security, mobile devices such as smartphones, tablets, PDAs, etc., without authentication check mechanisms like passwords, screen locks or fingerprint scans are at high risk [1, 2]. Such undefended devices always remain vulnerable to loss and compromise the stored sensitive information. In the worst case of loss or theft, the hackers or cyber criminals find one mechanism or another to bypass any form of authentication check and gain access to user sensitive information stored on the device.

12.2.2 Web-Based Threats

Modern mobile devices are designed to be persistently connected to WiFi networks or packet data internet to access web services. A major threat to the security of mobile devices arises through these networks. To execute web-based threats on a mobile device, its user must be prompted to visit an unsafe site and naively trigger a malicious process. Web-based threats can be classified into the following classes.

Applications such as email, messaging, Facebook, WhatsApp and Twitter are commonly used to spread links of malicious websites designed to scam the receiving users. Such scams are known as phishing scams [2]. Upon accessing such websites, the user is tricked into feeding his sensitive information like passwords or account numbers, which is captured by criminals for later exploit. The next level of possible threat connected to malicious links is drive-by downloads which automatically download a malicious application on user’s mobile device as they access such links. Some of such malicious apps prompt the user to click on or open the download for execution, while other apps can even start automatic execution. Another class of threats is known as browser exploit that utilizes the vulnerabilities present in the web browser installed on the mobile device or applications connected to it such as PDF file reader, flash player, shockwave file player or even image viewer, to damage the normal functionality of the device.

12.2.3 Application-Based Threats

Malicious mobile applications are often connected to websites with acceptable looks and behavior. As discussed in web-based threats, such malicious applications present a wide range of security threats to a mobile device. In continuation to this sequence, even legitimate software applications can also be exploited for deceitful purposes.

Application-based threats fit into one or more of the following classes. The first class of application-based threats is malware. Malware is an intentionally written piece of code to perform malicious actions on a target device [3]. Modern malware applications are capable of adding charges to a user’s phone bill, sending unwanted messages to contacts, accessing user’s private data or even hand over the control of the mobile device to a remote hacker without the knowledge of the user.

The next class of threatening applications for a mobile device is spyware. Spyware is a malicious application similar to malware, only it does not cause any visible harm to the normal functioning of the mobile device. Instead, a spyware silently collects user’s private data without their knowledge or consent. Text messages, phone call history logs, geographical location, browser history, contact list, private photos, contact lists and emails are some of the user data, which are generally targeted by spyware applications. Such data collected by spyware is exploited for financial fraud, blackmailing and even espionage cause a deep risk of privacy threats to the mobile device user. Another type of application-based threat is caused by vulnerable applications that contain faults exploitable for malicious intentions [28]. Such applications are generally legitimate ones with weaknesses due to improper designs or insufficient testing. Vulnerable applications allow access to sensitive user data for a criminal intent, execute fraudulent activities, disrupt the normal functioning of a service or even allow downloads of other similar malicious applications on the user’s device.

12.2.4 Network-Based Threats

Modern mobile devices are designed to ensure connectivity to local wireless networks (WiFi, Bluetooth) as well as cellular packet data networks to access web-based services. Threats from such networks are classified under network-based threats. Network exploits utilize flaws present in mobile operating systems or even the platform software on which the wireless or cellular networks function. On connecting to the user’s mobile device, these threats can provide the channel to an application or web-based threats [4].

WiFi sniffing is a common class of network threat that captures user data traveling through the network between the device and the network access points. Sending unencrypted data such as usernames, passwords or financial details via websites or applications lacking any security measures puts to privacy and security of user data at potential risk.

The next form of network threat to mobile devices is known as WiFI spoofing, which is executed by hackers by creating bogus WiFi access points for web access generally by using malicious WiFi routers. These WiFi points appear to be freely available public WiFi networks at public places, such as hotels, libraries, airports, railway stations or even coffee shops or hotels, with sufficiently familiar names like “Coffehouse Freenet” or “Airport Free WiFi” to attract users to connect to them. In worst cases, such malicious services prompt the user to create a user account with a username and password to access the free services. A large number of naive or ignorant users create accounts on such access points by using the same combination of email or username and password, that they use for many other services. This allows hackers to capture the victim’s sensitive user information and exploit it for malicious intent. Hence, extreme precaution must be taken while connecting to any new WiFi access point at any public place. In addition to this, users must never use personal details and regular account details to create accounts on such services. Instead, they should always use a unique combination of username and password to create a login on any new service. Compared to random or anonymous WiFi access spots with minimum or no security features, the paid wireless networks controlled by business groups with much more protected and controlled access should be preferred. Analysis of network traffic between router and mobile device of a victim user is known as session hijacking in cybersecurity terms.

In the case of mobile devices, a network attack known as sidejacking is employed to capture data from vulnerable data traffic. For this purpose, hackers use various tools to automate session hijacking via sidejacking attack [24]. A similar tool of this class has been developed by Mozilla as a plugin for Firefox web browser known as “Firesheep.” Firesheep [31] automates sidejacking between vulnerable WiFi networks and victim mobile devices to capture and exploit data traffic using a packet sniffer. Risk of compromise of wireless networks and mobile hotspots can be minimized by disabling automated search and by using secure wireless networks.

12.2.5 Data Transfer-Based Threats

Use of weak encryption algorithms or improper implementation of strong encryption techniques by the application developers can lead to cracked encryption threats. In the first case, many times developers use fragile encryption algorithms with well-known vulnerabilities only to speed up the development process [3, 5]. Such fragility attracts attackers to crack the applications and capture sensitive user data. In the later case, back doors or deficiencies are left open by developers while working with strong encryption techniques, which can also lead to the same impact on the privacy or security of user data. For example, multiple messaging applications provide encryption of user data only at sender and receiver ends. This leaves sufficient space for attackers in intermediate networks to capture the data and exploit it for malicious intent without any requirement of user details and passwords. Satisfactory enforcement of encryption practices through the network only practices encountering data transfer-based threats.

12.2.6 Improper Session Management-Based Threats

Many applications make use of runtime-generated access tokens to enable network access to connected devices. These access tokens also facilitate connectivity between the network and devices without repeated re-authentication for a predefined time limit. Applications with sufficient security features, generate new and confidential access tokens to enable network access for every session. Improper handling of session variables like access tokens, by the application, can naively leak them to malicious actors, risking the entire communication to illegitimate exploits.

12.2.7 Bluetooth-Based Threats

Bluetooth technology allows mobile devices to wirelessly exchange data among devices as well as connect peripherals like mouse and keyboards. But mobile devices with Bluetooth in the activated mode, set to be discoverable for other devices, are exposed to attacks such as blue snarfing, blue jacking and blue jugging discussed below [5]. Theft of private and sensitive user data, such as phone call logs, browsing history, GPS details, contacts, email communications and text messages, can be executed by using malicious software applications via Bluetooth. This theft of user data via Bluetooth is referred to as a Bluesnarfing attack. Hackers execute Bluesnarfing attacks by scanning for nearby devices with enabled Bluetooth via their smartphone or laptop. Applications used for bluesnarfing can steal data from victim’s mobile device in silent and undetectable mode. The worst aspect of bluesnarfing attack is that turning off Bluetooth on the device cannot guarantee security. This is because a mobile device with enabled but hidden Bluetooth can also be discovered and exploited by making a guess of its MAC address through brute force attack [25].

A Bluesnarfing attack causes theft of user data from the device, while a Bluebugging attack leads to the silent broadcast of anonymous and unwanted messages to other Bluetoothenabled devices without the victim’s consent and knowledge. A Bluejacking attack is executed by backdoor bypassing of victim’s mobile device access leading to silent compromise of control of their device. A bluejacking attack is capable of creating new entries in the address book, typing and transmitting new text messages and even transferring files via Bluetooth.

12.2.8 Application Platform-Based Threats

Despite thorough scanning, every mobile application submitted even to trusted online download platforms like Apple’s iTunes and Android Play Store cannot be guaranteed to be genuine and safe in all terms. Some suspicious applications may lead to unauthorized access to user credentials, siphoning of internet data or even make silent unapproved purchases from the user’s account. In the year 2010, a Vietnamese app developer was blacklisted from iTunes store by Apple Inc. The reason for this penalty was that he apparently charged users for books which they never purchased via his app. The developer committed this fraud only to boost his rating in the iTunes store and improve his ratings. To prevent such exploits, the users should try to install and use mobile apps of only trusted vendors and developers [26]. In a case where it is required to install an app from a new developer, a thorough study of app details like developer name, affiliations, user ratings and permissions required by an app, must be done.

A major category of such suspicious apps is free mobile apps available on these platforms. Such suspicious free mobile apps, like games or utility apps, are more likely to exploit device features and compromise user data. They are usually capable of accessing the internet, tracking user location and even accessing sensitive data. For example, 94% of gambling mobile games provided as free apps demand a user’s permission to send text messages, use the phone camera and even to make outgoing phone calls [26]. The users must be alert and substantiate the intent of such a free gaming app asking for access to these features.

But parallel to genuine application platforms mentioned above, there are also third-party application stores that provide alternative apps for users. Downloading and installing apps from these unauthorized platforms on a device can be very hazardous for the end user. Such application stores always remain at high risk of being run by cyber criminals by hosting fake copies of legitimate applications altered to execute fraudulent activities.

12.6.1 Mobile Identity Theft

One of the fastest growing types of threats to the security of the common masses is mobile identity theft. A major cause of this is the dominance of mobile devices such as smartphones and tablets in every sphere of modern society [10, 16]. The possible implications of mobile identity theft are discussed in this section.

1. Gather User Information: A mobile number is a unique communication entity reserved for an individual user or single group. Due to this uniqueness, many social media platforms, mobile apps and financial applications demand mobile numbers of their users as social identifiers. This fact leads to the possibility of a criminal or hacker to search for a smartphone number in a search engine or a website and collect information about a target user sufficient to exploit it for malicious intent. Such malicious intent may include social engineering scams or even financial damage simply by figuring out the true online identity of the victim. For example, if a user’s cell phone number is connected to his Facebook account, someone could use it to try and obtain his name either through the site’s general search by using the forgot password feature at login and entering the number instead of a name or email address [15].
2. Launch SMiShing Attacks and Phone Scams: If a user’s smartphone number gets into the hands of a criminal, they can use it to their advantage and try to scam the user via text messages which may be sufficiently convincing, especially if the scammer has done their homework on the user prior to their attempt.
3. Take over User’s Mobile Account: People search or reverse-lookup websites allow anyone to find out information about a cell phone number, including the carrier network provider, name and city/state associated with the number. Using information collected about the user, they will impersonate the user either in-person or over the phone to gain access to their mobile account. This enables them to upgrade for new phones for free (which they can sell for a profit), add additional lines or take over their number entirely (known as a SIM swap) [17]. They might also try to open up a mobile account at a different carrier using that information.
4. Gain Access to Financial Accounts: Beyond wreaking havoc on a mobile account, access to a mobile phone number enables cyber criminals to exploit the connected accounts by using SMS text message-based two-factor authentication. If the criminals own the control of the phone number linked to these accounts, the text message, email communication or even a phone call sent to verify a victim user’s identity will be sent to them instead of the real owner. This could enable them to change the passwords and get access to victim’s accounts, possibly leading to unauthorized charges on credit cards or a siphoning of bank accounts.
5. Terrorist Uses of Smartphone: Similar to criminals, terrorists have also worked up elaborate mechanisms to fraudulently acquire random cell phone numbers and devices under unsuspecting victims’ names. For extremely low prices, numbers and devices are accessible to terrorists for exploitation in their malicious objectives. Some such issues are presented below.
6. Burner Phones: A burner phone is an inexpensive and mostly refurbished mobile phone [18] designed for temporary use, after which it may be discarded. Burner phones are mostly purchased with prepaid minutes and without a contract. Using phones and increasing balances purchased with cash rather than a credit card and having no contract with a service provider clearly imply that no record of the user connected to the phone number can’t be traced. If the user suspects that the number has been traced or compromised, they can just dump the phone and purchase a new one, which would have a totally new number. Today, a large civil population uses smartphones, and smartphone numbers are increasingly being used as unique profile identifiers that connect user data across multiple databases. Moreover, phone numbers aren’t subject to privacy requirements like credit card details and social security numbers and thus are shared frequently. As a result, mobile number privacy is a growing security issue. An easy method of increasing mobile security is the use of burner phone mobile apps or services rather than using an actual device, which provides a temporary phone number that can be provided instead of the user’s actual cell number. One such application is the Burner mobile app [19] service, that has numbers that usually expire after a certain time period. These numbers can be used by paying for them with in-app purchases. If they lapse, they’re burned. The premium subscription gives the user a permanent second number. When a user calls via Burner, it actually calls Burner, which in turn replaces a relay call to the number you want to reach. Details of the Paris terror attacks [20] reveal that instead of encryption, consistent use of prepaid burner phones helped the terrorists to remain off the radar of the intelligence services. The three terrorist teams in Paris used only new phones, activated minutes before the attacks and discarded after use. Later, the investigators found a Samsung phone in a dustbin near a theater. The phone had a Belgian SIM card used only since the day before the attack. The phone was used to call just one other unidentified number in Belgium. As police pieced together the movements of the attackers, they found yet more burner phones.
7. Smartphone Bomb: Generally, two smartphones are used in the bomb-making process; one to call the other, which then transmits a signal to a circuit board and triggers the explosion [21]. Smartphones are basically small and sophisticated radio devices that translate a radio signal into an equivalent electrical pulse and convert that current into sound. If a smartphone is integrated with a bomb as a triggering device, the electrical impulse generated by the smartphone is adequate to create a detonation charge to trigger the main explosive compound of the bomb. Crafting a mobile phone into a remotely detonable bomb trigger is very easy and cheap due to the availability of online information and spare parts. Exploding such bombs also simply requires dialing the mobile number of the SIM in the phone connected to the detonator. The 28-year-old terrorist, Ahmad Khan Rahami, the suspect in twin bombings at locations in New Jersey and New York, admitted the use of smartphones [22] to detonate his homemade bombing devices. The Nokia 105 smartphone is a favorite device among ISIS fighters [23]. The cheap, durable and long battery life Nokia 105 phone is the most popular remote bomb-triggering device among ISIS organizations for detonating bombs. ISIS has assembled and deployed improvised explosive devices across the battlefield on a large scale, causing a large number of civilian and military casualties.”

12.6.2 Data Theft by Applications

Parallel to malicious mobile applications, in recent times some genuine applications have also been found to be continuously stealing data related to user communications and preferences. Such information is collected from data audio codecs of the call, duration of user calls, timestamps of user activities, frequently accessed contacts and far more. A similar case of data theft by a genuine chat application called “WhatsApp” was brought to light by researchers at the University of New Haven [27, 30].

The information stolen in real time was noted to be transferred to the official servers of WhatsApp¹. The researchers created some experimental participant users to conduct the experiment and tested the hypothesis of data theft by the app. After that, the users were authenticated by making calls on WhatsApp via a communication channel created by Opus codec at 8 and 16 KHz frequencies. Later, upon analyzing the destination IP addresses and relay servers for the calls, the experiment revealed that the application was stealing sensitive user data like call’s audio codec, phone numbers and timestamps of calls. The analysis of message exchange mechanism between the relay servers of the app and an Android version of the app also exposed the collection of data accumulation pattern of WhatsApp via FunXMPP² internet protocol. After this experimental case study of WhatsApp, it can be concluded that leakage, theft or silent monitoring of user information is also possible via even the most trusted and safe-looking mobile applications.

12.6.3 SIM Card Fraud

One of the most sophisticated and unusual techniques of mobile fraud that leads the criminals to access victim’s financial details is SIM card fraud. A combination of social engineering and exhaustive surveys paves the way for attackers to smoothly conduct this attack.

To start with, loosely handled, stolen or misplaced bank account statements of a potential target provide the access to bank details to attackers. After locating a potential target, the attackers conduct exhaustive social engineering and survey to collect and assemble sufficient personal information about the target from their social media account profiles including the details of their contact number and service provider. This survey enables the attackers to answer basic security questions to be asked by the mobile service provider of the target user.

Now the attackers call the target, convincing them to shut down their phone temporarily, either by repeatedly making blank calls or posing as a call for an upgrade from the mobile service provider. During the period when the phone of the target user is shut down, the attackers call the service provider of the target, pretending to be the target user and claim that their phone is damaged or lost. In such situations, the service provider company asks basic security questions which are successfully answered by the attacker, confirming the identity of the target. This leads the service provider to cancel the existing SIM and activating a new SIM possessed by the attacker.

Now, the attacker contacts the bank of the target user with their new SIM card and claims to have forgotten their access password. After asking basic security questions similar to the mobile service provider, the bank also sends a one-time access code or one-time password (OTP) to the phone number of the target user, which is actually received by the attacker.

Now the attacker opens a fake parallel account in the bank of the targeted user in his name and ultimately drains the user’s money into this new fake account without the user’s consent and knowledge. The worst part of this fraud is that the mobile user victim is totally unaware of this attack until their mobile seizes to operate or they are unable to access financial details of their bank accounts. By then, the attackers drain all the money from the victim’s fake account to finalize this attack.

12.7.1 Against Physical Loss and Theft of the Mobile Device

Physical loss of device due to theft or misplacement is a severe security threat because in addition to the financial damage of the device’s cost, the user also loses total physical control over their data. Concerning human nature and accidental possibilities, such physical losses cannot be guaranteed to stop, but their impacts can be sufficiently reduced if the users adopt the following measures:

1. Check security features provided by the mobile service provider: Generally, all mobile service vendors provide sufficiently strict security policies to help the users in protecting their data. Provision of secret security questions and PIN numbers are examples of these securities. Unique password combinations and random security questions, having no connection to the user’s social media profile are preferable for best use of these security features. It is also preferable for users to go through the security policy statements of service providers before signing up for any contract with them.
2. Don’t store critical information on the mobile device: Sensitive information details, such as account passwords, PIN numbers, financial details, etc., are at high risk for loss or theft if stored in texts or emails. Theft or loss of mobile devices must be immediately shared with the service providers to help them remotely deactivate the device as soon as possible. After this, the user must change passwords of all connected online accounts accessible through their stolen device.
3. Setting up sufficiently strong access passcodes: In case of theft or loss, a strong passcode safeguards user’s data to a satisfactory level. Lack of any passcode or knowledge of this passcode by many people risks the security of the data present on the device to a great extent.
4. Regular and cloud-based backup: Mobile users must regularly back up their data stored on their devices on secondary storage devices such as external backup drives or memory cards. To improve the security level and accessibility, same data can also be saved to cloud-based backup services. This will allow the user to remotely access, update and restore their data from any location in case their device is lost, stolen or is even accidentally erased.
5. Proper erasing of data before switching to a new device: Before recycling, donating or even reselling the mobile device, erasing the data efficiently from the old device helps to protect its privacy and security. For this purpose, certain devices, as well as software applications, are available that ensure satisfactory deletion of old data.
6. Installing tracking apps on the device: Modern mobile devices are equipped with remote tracking, locking and even data wiping features. Multiple unsuccessful login attempts can lead to self-destruction of stored data on the device. Several applications are now also available to provide these features.

12.7.2 Against SMiShing Attacks

As discussed earlier, SMiShing attacks act as bait for mobile users who are potential targets for exploitation by cyber criminals. Generally, SMiShing attempts are social engineering attacks embedded in text or phone call formats to prompt the victim to naively attempt the security violation of their device. But following precautions can save the mobile users from SMiShing attacks to a great extent.

1. Never click on a suspicious link or number: On receiving a text message or phone call with a suspicious content or from an unknown source prompting to perform a specific action by clicking on a link or dialing a given number, the user must never perform the suggested action. This inactivity will automatically disarm the thrown bait of the remote fraudster or cyber criminal.
   Even if such a message prompts in a prohibitive way like to stop receiving such messages in the future, click the NO button at the bottom or if you do not wish to receive such messages in the future, simply respond by texting “NO”; the user must avoid performing the suggested negative action, as it might lead to the same consequential exploits mentioned above.
2. Confirm the validity of the source: On receiving such doubtful communication, the target user should always try to ensure its originating source or sender. This search for its source can be done on search engines or address directories over the web.
3. In case of imposters, confirm from the original authorities: If a doubtful message or call pretending to be from one of the known sources, prompts the user for certain action, it is better to contact the original authority to confirm the message. For example, if a user receives a message from his bank such as “Your policy reward points are about to lapse in 2 days, click on the link to claim your points.” Here, instead of clicking on the link, and possibly surrendering their financial information, the user should contact their bank directly to confirm the validity of the message.
4. Never provide any personal or sensitive information: The scope of personal or sensitive information ranges from financial details, one time passwords (OTP), user account details to even name and address of the target user. SMiShing links commonly threaten the target mobile users with blocking or disruption of a specific service such as blocking of account or credit card penalties. Surrendering any such information may lead to serious consequences against the security of linked data. Instead, the users must remember that any authorities of any legitimate service will never ask them about their sensitive information. In case of persisting doubt, the users must themselves contact the authorized personnel of the service.

12.7.3 Against App-Based Attacks

1. Download from trusted application platforms only: Try to always download a mobile application from trusted mobile app download platforms like “Google Play Store”³ for Android device and “iTunes”⁴ for Apple devices. Applications loaded on these platforms are thoroughly tested and confirmed for their behavior and security by the authorities to maintain the trust and repute of the hosting companies. Apps downloaded from unknown or untrusted platforms may carry malware or spyware that can risk the security of the user data and device [29].
2. Exhaustively examine the details of the app before downloading: Ratings provided by users, history and reviews about the authors and update history of the app must be carefully examined before installation of any app even from the most trusted sources mentioned above. This check can save the user from any unexpected loss or damage due to the app, previously experienced by other users.
3. Check the app permissions before installation: The user must cautiously read and then grant permissions to the new app for accessing the device data and services. This scrutiny is extremely important for any app to know its intended future behavior after installation on the device. Any unexpected demand for access permission like access to the camera for a gaming app must be reported accordingly.
4. Checking phone bill: In cases of abnormal data exchange, sudden deprecated battery life or heating of the device, do check the bill incurred due to the device. The bill may project unexpected rises due to suspicious calling charges or unexpected text message exchanges.
5. Install security app: The users must install a security application that scans the behavior of every app installed on the device. In case of any spyware or malware, the security app will alarm the user of the abnormal behavior of the app.

12.7.4 Against Identity Theft and SIM Card Fraud

To protect cell phone number, there are certainly some actions that the users can take to protect themselves from falling victim to cell phone number identity theft.

1. Staying vigilant: The users must get in the habit of checking their bank and phone accounts frequently to make sure there’s no suspicious activity. Staying up-to-date with any attacks that have hit companies they shop with will make sure that they aren’t among the victims.
2. Utilizing the safeguards provided by companies: The email based or one-time password (OTP)-based authentications can certainly be exploited by criminals. But their utter absence can expose the user against higher proximity of attacks.
3. Creating a PIN number for mobile phone accounts: Creation of PIN for mobile services is an optional security process provided by the services providers. But a PIN-based access creates an extra layer of security for the user’s account by enforcing a 4 or 6 digit access restriction prior to performing any crucial account changes.
4. Use of unique and strong security access combinations: Strong passwords consist of a unique combination of alphabets, special characters and numbers with a sufficient length. Similarly, selection of security questions and their answers must be unrelated to any social media profile of the user.
5. Do not make personal information public: Too much exposure of personal information on social media can help criminals to answer security questions to access the details of the target user. If information about common facts like hometown, spouse name, details of family members, own and their birthday, mother’s maiden name, the name of the first pet, is available on users’ social media profiles, it may risk the security of user data to a great extent. In addition, the users must keep checking their social network privacy settings to ensure that their information isn’t easily harvestable.
6. Use a virtual number for noncritical use: One of the best ways to limit the amount of personally identifying data tied to a main contact number is to avoid sharing it with anyone except the closest trusted individuals. Use of virtual numbers for nonpersonal matters can help to sustain privacy in such cases. Virtual numbers can accept text messages and phone calls and can be set to forward to the actual contact number to avoid missing any genuine and important communications.
7. Establish a PIN or password with the mobile carrier: All mobile service providers allow their users to set up an additional password or SIM-based PIN code that can be required to make any changes to the mobile account. This safeguard mechanism can critically help in case of SIM card-based fraud. Here, even if the criminal acquires a new SIM with user’s number, he won’t be able to access it without the SIM-based PIN code.
8. Report suspicious activity immediately: If the phone suddenly becomes disconnected and restarting it doesn’t make any changes to the signal, or the phone bill has sudden unknown hikes, or the phone is receiving multiple repeated nuisance calls, the user must contact their mobile carrier immediately.

The sooner such abnormalities as observed and acted upon, the lesser is the extent of damage caused. Users must be also on alert for suspicious phone calls or messages pretending to be from their mobile carrier.