How to Know if Your Phone Is Hacked – 10 Signs

How to know if your phone is hacked starts with understanding what has changed.

A compromised phone does not always make itself obvious. The first signs are often subtle: unusual battery drain, unfamiliar apps, strange pop-ups, or account activity that does not look right.

In this guide, we explain the warning signs to look for, what they may mean, and what to do if you think your phone has been hacked. 

Can Your Phone Get Hacked?

Yes. A phone can be hacked just like any other internet-connected device.

In many ways, smartphones are especially attractive targets. They often hold access to email, banking apps, social media, saved passwords, photos, and other sensitive data. For an attacker, that makes a phone highly valuable.

Understanding the warning signs is the first step in protecting your data and regaining control.

How to Tell if Your Phone Is Hacked: 10 Signs to Look Out For

A hacked phone is not always easy to spot. In many cases, the warning signs start small: unusual slowdowns, unfamiliar apps, or activity that does not look like your own.

Here are 10 common indicators that your phone may have been hacked:

1. You notice apps you did not install

If you see unfamiliar apps on your phone that you do not remember downloading, that can be a warning sign. Attackers sometimes install malicious apps to monitor activity, steal data, or create ongoing access to the device.

With that said, not every unknown app is malicious. Some phones come with pre-installed software or carrier apps. The question is whether the app looks unexpected and appeared without a clear reason.

2. Your battery drains unusually fast

A sudden drop in battery life can point to malicious processes running in the background. Spyware, tracking tools, or other unauthorized apps may stay active even when you are not using your phone.

Battery issues can also have normal causes, but if the drain feels new, persistent, and out of proportion to your usage, it is worth investigating.

3. Your phone feels much slower than usual

If your phone becomes sluggish without explanation, malware could be consuming processing power in the background. You may notice apps taking longer to open, delayed responses, or a general drop in performance.

In some cases, this may also come with freezing, crashing, or random restarts.

4. You see strange activity in your online accounts

If accounts linked to your phone show unusual behavior, that can be a serious red flag. This may include login alerts, password reset emails you did not request, changed settings, or messages sent from your account without your knowledge.

A hacked phone can give an attacker access to saved credentials, authentication codes, or account sessions.

5. Your call logs or text messages look unfamiliar

Unrecognized calls, strange outgoing messages, or texts you did not send can suggest unauthorized activity. In some cases, attackers use compromised devices to send spam messages, interact with premium-rate services, or test whether they still have control of the phone.

Review your call history and messages carefully if something feels off.

6. You get persistent pop-ups or suspicious ads

Frequent pop-ups, especially outside your browser or normal apps, may point to adware or other unwanted software. These pop-ups often try to push fake warnings, unsafe downloads, or misleading prompts.

A clean phone should not constantly interrupt you with aggressive or random ads.

7. Your mobile data usage suddenly increases

If your data usage spikes without any change in your behavior, background malware may be using your connection. Some malicious apps quietly send information to external servers, load hidden ads, or maintain contact with an attacker.

Unexpected data use is one of the more overlooked signs of compromise.

8. Websites or browser behavior look unusual

If websites suddenly appear distorted, redirect you unexpectedly, or load versions that look different from normal, your browser or phone may have been tampered with.

This can happen through malicious browser settings, unsafe extensions, or malware that redirects traffic to harmful pages.

9. You notice unexpected charges on your bill

Unfamiliar fees on your phone bill can sometimes be linked to malicious apps or unauthorized subscriptions. Some forms of mobile malware trigger premium SMS messages, hidden purchases, or recurring charges without making it obvious to the user.

If your bill changes and you do not know why, do not ignore it.

10. Your phone overheats even when you are not using it

A phone that becomes unusually hot while idle may be running hidden processes in the background. Malware, spyware, or unauthorized mining activity can increase device load and generate heat even when the screen is off or the phone appears inactive.

Occasional warmth is normal. Constant overheating without a clear cause is not.

Expert tip from Serus

One sign alone does not always mean your phone is hacked. What matters is the pattern.

If several warning signs appear at once, or your phone suddenly behaves differently without a clear reason, it may point to a real compromise. The earlier you spot that pattern, the easier it is to act.

Common Ways a Phone Can Be Hacked

Phones can be compromised in several ways. Some attacks rely on malicious software. Others depend on deception, weak connections, or flaws in the device itself.

Here are some of the most common ways cybercriminals hack phones:

Malware

Malware is one of the most common ways a phone is compromised. Once installed, it can steal data, monitor activity, damage files, or give an attacker access to the device.

Common examples include:

• Keyloggers

These record what you type, including passwords, payment details, and other sensitive information.

• Trojans

These disguise themselves as legitimate apps or files but contain malicious code that can open access to your device.

Phishing

Phishing attacks use fake emails, text messages, or websites to trick you into clicking a link, downloading a file, or sharing personal information.

In many cases, the message looks legitimate. That is what makes it effective.

Malicious messages and software exploits

Some attacks use specially crafted messages or commands to exploit weaknesses in a phone’s software. If the device is vulnerable, the attacker may be able to run malicious code or gain deeper access.

This is also why jailbreaking or removing built-in security restrictions increases risk. It can expose the operating system to threats it was designed to block.

SIM swapping

A SIM swap attack happens when a criminal convinces a mobile carrier to transfer your phone number to a SIM card they control.

Once that happens, they may be able to intercept calls, text messages, and authentication codes tied to your accounts.

Unsafe Wi-Fi, Bluetooth, and NFC

Unsecured wireless connections can create openings for attackers.

This includes:

• public Wi-Fi networks

• exposed Bluetooth connections

• NFC-based interactions such as contactless payments

If these channels are not properly secured, attackers may intercept data or manipulate communications.

Malicious cables and charging stations

Although less common, malicious USB cables or compromised public charging stations can be used to deliver harmful code or access device data.

Connecting a phone to an untrusted cable or charging point always creates some level of risk.

Cryptojacking

Cryptojacking happens when mining software is secretly installed on a phone and uses the device’s processing power to generate cryptocurrency.

This often causes:

• overheating

• poor performance

• fast battery drain

It may also create broader security exposure by giving attackers a foothold on the device.

Fake cell towers

Fake cell towers, sometimes called IMSI catchers or Stingrays, imitate legitimate mobile towers and trick nearby phones into connecting to them.

Once connected, attackers may be able to monitor calls, intercept text messages, or track location data.

Spyware

Spyware is designed to monitor a user without their knowledge. Depending on the level of access, it may collect messages, browsing history, login details, location data, or even microphone and camera activity.

Some spyware is relatively simple. Other tools are highly advanced and designed for targeted surveillance.

What to Do If Your Phone Is Hacked

If you think your phone has been hacked, act quickly. The goal is to remove access, reduce exposure, and regain control before more damage is done.

Remove suspicious apps

Review your installed apps carefully and delete anything unfamiliar, unnecessary, or suspicious. Malicious software is not always obvious and may appear as a harmless app or background tool.

Run a trusted security scan

Use a reliable mobile security or anti-malware tool to scan your phone for malicious software. This can help identify threats that are not visible at the surface level.

Turn off unnecessary connections

Disable Bluetooth, personal hotspot, and other wireless connections when you are not using them. If an attacker is nearby or a connection has been exposed, reducing open channels can help limit further access.

Change your passwords

Update the passwords for your most important accounts as soon as possible, especially email, banking, cloud storage, and social media. If possible, do this from a different trusted device.

Warn your contacts

If your phone has been used to send suspicious messages, let your contacts know. This helps prevent phishing, fraud, or malware from spreading further through your accounts.

Reset the device if needed

If the issue continues or the compromise appears serious, a factory reset may be necessary. This should be treated as a last step, since it removes the data stored on the device. Back up important files first, then follow the official reset instructions for your phone.

How to Protect Your Phone From Being Hacked

Protecting your phone does not require extreme measures. In most cases, it comes down to reducing unnecessary exposure and building better habits around access, apps, and connections.

Keep your phone physically secure

Physical access still matters. Do not leave your phone unattended, and make sure it is protected with a strong passcode, not a simple or predictable one.

Use strong, unique passwords

Weak or reused passwords make it easier for attackers to access your accounts. Use a different password for each account, especially for email, banking, and cloud services.

Use a password manager

A password manager helps you create and store strong, unique passwords securely. It also reduces the temptation to reuse the same password across services.

Turn on two-factor authentication

Two-factor authentication adds another layer of protection beyond your password. If an account supports it, enable it. App-based authentication is usually stronger than SMS.

Be cautious with messages and links

Phishing remains one of the most common ways attackers compromise phones. Avoid clicking unexpected links, opening suspicious attachments, or responding to messages that create urgency without clear reason.

Avoid unsafe apps

Only download apps from trusted sources, and take a moment to review permissions, ratings, and developer details before installing. If something feels off, do not install it.

Keep your phone and apps updated

Software updates often include important security fixes. Keeping your operating system and apps current helps close known vulnerabilities before they can be exploited.

Avoid public Wi-Fi without protection

Unsecured public Wi-Fi can expose your traffic to attackers. If you need to use it, a trusted VPN adds an extra layer of protection.

Turn off Bluetooth and hotspot when not in use

Open wireless connections create unnecessary exposure. If you are not actively using Bluetooth or hotspot, switch them off.

Do not jailbreak or root your phone

Jailbreaking or rooting removes built-in security protections and makes the device easier to compromise. The extra flexibility is rarely worth the increased risk.

Use mobile security software

Reliable anti-malware or mobile security tools can help detect suspicious apps, scan for threats, and provide extra visibility into device behavior.

Lock your SIM card

Adding a PIN to your SIM card can help protect against unauthorized use and make SIM-related attacks harder to carry out.

Serus helps you monitor what is visible online, reduce your exposure, and stay in control of your personal data.

FAQ

Can you tell if your phone has been hacked?

Sometimes, but not with certainty from one sign alone. A hacked phone usually reveals itself through a pattern, such as unusual battery drain, slower performance, unfamiliar apps, suspicious account activity, or unexpected pop-ups. If several of these signs appear together, the risk is more credible.

Can I run a test to see if my phone is hacked?

There is no single test that can confirm whether your phone has been hacked. The safest approach is to check for warning signs, review installed apps and account activity, and run a trusted mobile security scan if needed.

Does *#21# tell you if your phone has been hacked?

No. *#21# does not tell you whether your phone has been hacked. It is a code used to check call forwarding status, not a hacking test.

Can you tell if someone is accessing your phone?

Not always directly, but there can be warning signs. Unfamiliar apps, account changes you did not make, strange texts or calls, unusual data usage, or a phone that suddenly runs hot or slow can all suggest unauthorized access.