Ray Walsh, a digital privacy expert at ProPrivacy, points out that in addition to quicker battery drain, a phone feeling warm even when not in use could indicate unusually rapid consumption of internet data. “If users find themselves consistently exceeding their data limits,” he adds, “it’s possible someone is ‘piggybacking’ on their sessions.”

If your phone suddenly exhibits slower page loading or frequent crashes, security expert Robert Siciliano, CEO of Safr.Me, suggests starting by shutting it down and observing its behavior afterward. “Hacked phones often exhibit difficulty shutting down properly or may refuse to shut down despite your commands,” he notes. It’s worth noting that your phone isn’t the sole device vulnerable to such risks. Additionally, be attentive to any timing discrepancies in other functions on your iPhone or Android. “Delays in sending and receiving texts, making phone calls, or checking voicemails are abnormal and may indicate a phone hack,” advises Alexis Moore, author of Surviving a Cyberstalker. “While these signs are subtle, they’re crucial to notice in today’s cyber age where everyone is constantly multitasking and may overlook such details.”

Utilize an app like Data Usage, which is accessible for both Android and iOS platforms, to track the amount of data being transmitted from your device. “Keep an eye out for any irregularities or unusually prolonged periods of uploading,” advises Allan N. Buxton, lead forensic examiner at Secure Forensics. “Typically, users exhibit consistent monthly activities. Therefore, a significant spike or continual increase in uploaded data without a plausible real-world explanation may suggest the presence of monitoring software.”

Rob Webber, CEO and founder of MoneySavingPro.com, adds, “Keep an eye out for calls and texts sent to numbers not in your contacts list. It’s crucial to monitor this closely, as some of these may be premium-rate numbers that malware is compelling your phone to contact, with the profits going directly to the individual who compromised your device.” Additionally, remain vigilant for iPhone calendar spam.

“Another red flag indicating a compromised smartphone is the presence of spammy pop-ups or unusual screensavers,” adds Webber. “Although not every pop-up signifies a breach, a surge in their frequency could suggest your phone has been infected with adware. This type of malware coerces devices into visiting certain sites to generate revenue through clicks.” It’s advisable to understand how to clear cookies on your phone to safeguard your private information and prevent hackers from manipulating the pop-ups you encounter.

“Be cautious of new apps that unexpectedly appear on your screen or within your iPhone’s settings,” advises Walsh. “Regularly inspect the list of running apps, and if anything appears suspicious, investigate whether an app draining your battery is associated with malware or other malicious activities.” Furthermore, if such apps are present on your phone, it’s possible that someone may be spying on you.

Matthew Woodley of Woodley Digital Marketing warns that unusual activity on your Gmail or iCloud accounts is a common indicator of a malicious hack and poses a significant threat to your data. “Both of these services store extensive information about you, including passwords, photos, location data, messages, and calls,” he explains. Cybercriminals have been known to hold your photos for ransom, and your email address likely serves as the backup for all your online accounts. “With enough information from your email, identity theft becomes easy,” Woodley adds.

So, what constitutes unusual behavior? “Be vigilant for emails regarding password resets that you didn’t initiate, security alerts informing you of access to your email or social media accounts from a new device, or verification emails indicating sign-ups for unfamiliar accounts,” advises Webber. These are all indications that your iPhone or Android device may have been compromised.

Kayne McGladrey, Director of Security and Information Technology at Pensar Development, describes a concerning scenario known as a number porting attack, which is effective against both Androids and iPhones across all mobile carriers. “If you suspect you’re a victim of a number porting attack,” he advises, “immediately contact the authorities to report identity theft and inform them that your mobile number has been ported out. It’s crucial to notify your mobile provider as well, and you may need to provide a police report to substantiate your claim as a victim of identity theft.”

Noticeable signs that your camera or microphone is active without your initiation could mean someone is spying on you.

Phishing is a deceptive scheme where a user is tricked into divulging sensitive information. According to cyber expert Emmanuel Eze from TechCopp.com, it often involves receiving a text, supposedly from someone familiar like a friend or family member, urging the recipient to open a file, such as a PDF or photo. However, once opened, a Trojan horse program embedded within the file can either corrupt the entire system or grant unauthorized access to steal files.

Waller adds that a common consequence of such hacks may involve receiving a message from an unknown sender demanding money, threatening to release stolen pictures and messages from the victim’s phone. To safeguard against such attacks, it’s essential to refrain from clicking on suspicious links or attachments unless their legitimacy can be verified from a trusted source. When in doubt, the safest course of action is to delete the suspicious content.

When away from home, it’s advisable to avoid using public USB ports and instead rely on AC charging ports to charge your phone. Emmanuel Eze from TechCopp.com warns that hackers have been known to conceal mini-computers and malware within public chargers and USB cables. “Malicious charging stations exploit the dual functionality of USB for both file transfer and charging,” he explains. “Some hackers can even monitor your keystrokes while your phone is plugged in, tricking you into thinking you’re merely charging your device while you’re actually being hacked. Therefore, it’s important not to rush into plugging your phone into any outlet you come across.” Be cautious and avoid charging your phone in certain places to mitigate the risk of falling victim to such attacks.

Alex Hamerstone, GRC practice lead at TrustedSec, highlights the growing concern among consumers regarding the concealment of mobile malware or malicious functionalities within seemingly legitimate apps. “Criminals are increasingly embedding such capabilities into apps that may appear genuine or even offer legitimate services, such as mobile games,” he explains. Hamerstone points out that Google Play is more susceptible to hosting infected apps compared to Apple’s App Store, primarily due to Google’s less stringent vetting process for these apps.

Gary Davis, Chief Consumer Security Evangelist at McAfee, emphasizes the importance of safeguarding your device in public settings. “While online threats are prevalent, it’s crucial to remain vigilant against real-world dangers, such as opportunistic theft,” he cautions. Davis advises keeping your smartphone either on your person or within sight while in public. Additionally, he recommends disabling the ‘phone visibility’ option, which allows nearby devices to detect and exchange data with your phone. Furthermore, Davis stresses the importance of refraining from saving passwords or login information for sensitive accounts on your device, as this could potentially allow hackers to gain automatic access in case of a breach.

In a related context, when disposing of an old phone, it’s essential to follow cell phone recycling tips to prevent your private information from falling into the wrong hands.

Thomas Reed, Director of Mac and Mobile at Malwarebytes, underscores the significant risks associated with poor password management practices. “If someone’s iCloud account is compromised,” he explains, “the hacker could potentially access the location of all their devices, view their iCloud-stored data, and even activate anti-theft features to lock their devices.” Reed highlights that such breaches often occur when individuals reuse passwords across multiple sites, and one of those sites becomes compromised.

To mitigate these risks, Reed recommends employing unique passwords for each site, stored securely in a password manager. Additionally, enabling two-factor authentication on all possible accounts adds an extra layer of security. These measures are essential for safeguarding against common password mistakes that hackers exploit.

Woodley highlights the risks associated with using free and unsecured WiFi networks, such as those found at local coffee shops. “Unfortunately, these networks make it easy for hackers to spy on your online activities,” he warns. To protect yourself while using unsecured WiFi, Woodley recommends utilizing a VPN (virtual private network) service to encrypt your connection and keep it secure. While VPN services are inexpensive, they provide a crucial layer of protection.

If opting not to use a VPN, Woodley advises against accessing sensitive information such as banking websites or email accounts while connected to unsecured WiFi. However, if necessary, he recommends scrutinizing the address bar for indicators of a secure connection. Look for the prefix “https://” instead of “http://” and ensure there’s a green lock symbol next to the URL. If these indicators are absent, refrain from entering any login information to avoid potential security risks.

Unusual charges or a significant increase in your phone bill can indicate that your phone is making unauthorized calls or sending messages to premium numbers controlled by hackers.

If your phone restarts for no apparent reason, it could be under the control of an unauthorized user or software.

Malware can prevent your phone from shutting down properly or cause it to restart immediately after you attempt to turn it off.

Eavesdropping software might cause strange noises or echoes during phone calls, indicating that your conversations are being monitored.

Malware can block access to security apps or settings, preventing you from detecting or removing it.

Keep an eye on your bank and credit card statements for unauthorized transactions, as compromised phones can be used to steal financial information.

Unauthorized changes to your settings, such as security features being disabled, can indicate that someone else has access to your device.

Receiving nonsensical messages containing symbols, numbers, or random characters can be a sign of command and control messages from hackers.

If posts, messages, or friend requests are being sent from your social media accounts without your knowledge, your device may be compromised.

Malware can cause your phone to automatically connect to unknown Bluetooth devices, potentially allowing hackers access to your data.

If websites start to look strange or display differently, it could be a sign of malware intercepting and altering your web traffic.

Finding sites in your browser history that you did not visit can indicate that malware is using your device to click on websites in the background.

If your antivirus or other security software is disabled without your action, it’s a strong indication of malicious tampering.