Can Someone Spy on Your Phone Without You Knowing?

Sophia Taylor

By Sophia Taylor


Our phones have become a huge part of our everyday lives, serving as the primary storage for our private and personal data.

So, protecting this data from those who want to spy on us is more important than ever.

If your phone gets hacked, you might imagine there would be many tell-tale signs to look out for, such as annoying pop-ups appearing on the screen, being redirected to dodgy websites, or even being bombarded with apps you didn’t ask for.

However, in reality, phone hacking can often leave little to no trace. In this article we’ll explore the ways that someone can spy on your phone without your knowledge.

6 Ways Someone Can Use Your Phone to Spy on You without Your Knowledge

1️⃣ Spyware

Disturbingly, spyware tools are readily available online for as little as $30. This price point makes it accessible to abusers and stalkers—not just skilled hackers.

This spyware is designed to evade detection on a mobile device and is available on both iOS and Android operating systems.

Here’s how these spyware apps can be installed on an Apple and Android device:

📱 iOS

Installing spy apps on an iPhone involves bypassing Apple’s security restrictions. Apple devices have strong security, but you can bypass this protection through a process called jailbreaking.

Jailbreaking often involves simple tools that are readily available online.

💡 What Is Jailbreaking?

Jailbreaking is the process of removing software restrictions imposed by Apple on devices running its iOS operating system (iPhones, iPads, etc.).

This allows users to install apps and software from sources other than the official App Store and customize their devices in ways Apple doesn't normally permit.

📱 Android

For Android devices, jailbreaking is usually unnecessary. A hacker simply needs to tweak a few settings to install spy apps.

For example, if they disabled Google Play Protect, they would be able to install the spyware hassle-free.

Can it spy without your knowledge?

Once spyware is installed, the hacker can easily hide the app icon. This allows the spyware to continue functioning in the background, and most people would never know that their phone was being spied on.

Here are some of the capabilities of mobile spyware:

Listening to phone calls: Accesses your contacts, call history and even secretly records your conversations in real-time.

Recording keystrokes: Captures everything you type, including passwords and sensitive information.

Tracking location: Uses GPS and network information to track your movements in real-time.

Accessing communications: Reads your text messages, emails, and chats in social media apps.

Capturing media: Uses your device’s camera and microphone to record images, video, and audio.

Monitoring Internet activity: Keeps tabs on your browsing history and downloads.

Signs you have spyware installed

If spyware has infected your phone, several signs can alert you to its presence:

⚠️ Unusual battery drain: Spyware runs in the background continuously, leading to faster battery depletion.

⚠️ Increased mobile data usage: Spyware often sends data from your phone to a remote server, resulting in higher data usage than normal.

⚠️ Strange phone behavior: Unexpected crashes, slow performance, or apps taking longer to open can indicate spyware activity.

⚠️ Unfamiliar apps or icons: The appearance of apps or icons you don’t recognize or didn’t install can be a direct sign of spyware.

⚠️ Odd text messages: Receiving strange text messages containing symbols, numbers, or characters that don’t make sense may indicate command messages sent to spyware.

⚠️ Background noises during calls: Unusual noises or echoes during phone calls can suggest your calls are being recorded.

⚠️ Unexplained activity: Posts, messages, or emails sent from your account that you didn’t create could be the work of spyware.

⚠️ Pop-ups or ads: Excessive pop-ups or ads, especially outside of a web browser, can indicate adware, a form of spyware.

⚠️ Increased phone temperature: Spyware can make your phone work harder, causing it to feel hot even when you’re not using it heavily.

⚠️ GPS icon activated: Seeing the GPS icon active without using any location-based services can suggest your location is being tracked.

🛡️ Run a spyware scan

While the above signs can be good indicators of spyware, the only way to be certain is to run a scan with a spyware detection tool.

Use one of Certo’s apps to run an in-depth scan for spyware and other cyber threats.

2️⃣ Family-tracking apps

Family tracking apps are designed for location sharing and safety purposes within a family or friend group. However, some apps’ extensive monitoring features can enable someone to misuse them for intrusive spying without the target’s full knowledge or consent.

Tracking apps don’t generally require any special technical knowledge to install, other than downloading the app as you would any other.

These apps can track your real-time location and keep a detailed history of where you have been in the last 30 days. Some apps even extend the tracking to messages, phone calls and browsing history.

This data can be used to intrusively monitor your activities, beyond the intended purpose of family tracking.

Can it spy without your knowledge?

Unfortunately, tracking apps can operate without your knowledge. While they can’t be completely hidden like traditional spyware, they can be disguised in several ways:

⚠️ Tucked away: The app could be moved to a rarely-used folder on your device, making it less likely to be found during casual browsing.

⚠️ Partial consent: The app might be installed under the guise of safety, but you may not be fully aware of the extent of its tracking features.

Unless you’re actively searching for a tracking app, it could take significant time to stumble upon it by accident. This means a hacker or someone misusing the app could track you for a long period before you realize it.

What to do If you suspect a malicious tracking app is installed on your phone

✅ In your device settings, go through your installed apps. Look for unknown apps or apps with names like “Family Tracker”, “Find Your Friends”, “GPS Location Tracker” etc.

✅ Check your battery settings for any app consuming excessive power. Continuous location tracking can be a culprit.

✅ Tracking apps transmit your information over the internet. Look out for any apps with unusually high data usage in your device settings.

✅ A constantly active GPS icon when you’re not using location-based apps could indicate background tracking.

✅ Check if any unfamiliar apps have enabled accessibility features, which can allow monitoring.

✅ Run a scan with reputable iPhone or Android security software. Some might flag overly intrusive tracking apps.

Fig 1. Finding a tracking app with Certo Mobile Security for Android.

3️⃣ Cloud-synced data

If a hacker knows the login details to your iCloud or Google account, they can download data you’ve synced between your phone and the cloud. They may even be able to create a full clone of your device.

While this won’t give them access to ‘live’ data, such as listening to phone calls or watching you through your camera, it will allow them to view and steal any data synced to the cloud.

This may include messages, photos, contacts, notes, and more.

Can it spy without your knowledge?

Yes, such hacking can occur discreetly without any noticeable changes on your device. Since the attack targets cloud accounts rather than installing malicious software on your phone, there might not be immediate, visible signs of compromise.

However, subtle indicators could suggest unauthorized access, such as:

  • Unexpected account activity
  • Disabled two-factor authentication (2FA)
  • New devices linked to your cloud services without your consent

How to detect a cloud data breach

To detect a breach, carefully monitor these areas within your cloud services:

➡️ Account activity: Regularly review login history and active sessions. Investigate any access from unfamiliar devices or locations.

➡️ Security notifications: Pay close attention to emails from your cloud provider about:

  • New logins
  • Password changes
  • Attempts to disable 2FA

➡️ App permissions: Regularly review the permissions of third-party apps and devices connected to your cloud account. Revoke access to any you don’t recognize or no longer use.

➡️ Unexpected 2FA behavior: Be alert for unexpected two-factor authentication prompts or notifications about 2FA being disabled.

➡️ Data changes: Keep an eye out for missing or altered files within your synced data.

➡️ Unknown devices: Check for and remove any unfamiliar devices appearing in your account settings.

What to do if you suspect a data breach

If you suspect a breach, change your cloud account password immediately.

✅ Enable 2FA, as this adds a powerful layer of security beyond your password.

✅ Within your cloud account settings, check for unauthorized devices and remove them.

✅ Scrutinize bank and credit card statements for unusual activity, as hackers might have stolen financial information from your synced data.

💡 Pro-tip: Be proactive in checking these areas regularly. The sooner you detect unusual activity, the faster you can secure your account(s).

4️⃣ Custom third-party keyboards

You can install third-party keyboards from the Google Play Store or Apple’s App Store. These apps are designed to replace your phone’s default keyboard.

Spyware apps could be disguised as a fun keyboard with new emojis, a language-translation keyboard, or something similar.

Malicious custom keyboards could even be installed by a hacker as part of a targeted cyber attack.

When installing a keyboard, it often requests extensive permissions. These permissions are vital for its functionality, but a malicious keyboard might request more than necessary, including:

  • Access to everything you type, including passwords, banking details, and sensitive messages.
  • Network access (to transmit your data to the hacker).

While you type, the malicious keyboard logs every keystroke. This information is either stored on your device to be retrieved later or continuously transmitted to the hacker’s remote server.

Can it spy without your knowledge?

A malicious keyboard can spy without your knowledge. You often download these keyboards from official app stores, which gives you a false sense of security.

Once installed, a malicious keyboard operates just like a regular one. It can be difficult to tell if anything harmful is happening in the background. They can also be made to look almost identical to the default iOS or Android keyboard meaning they could go unnoticed for a long period of time.

Default iOS keyboard (left) vs. custom keyboard with keylogging capability (right)

Fig 2. Default iOS keyboard (left) vs. custom keyboard with keylogging capability (right).

How to remove a third-party keyboard

To check for and delete unrecognized custom keyboards on Android and iOS phones, follow these steps:

➡️ iOS: Go to Settings > General > Keyboard > Keyboards. Look for anything you don’t recognize.

➡️ Android: The process varies on Android phones, but generally, you’ll find the keyboard settings within your main Settings app, often under ‘Languages and Input’ or a similar category. Look for unfamiliar keyboards.

Additional tips:

✅ Stick to reputable keyboards: Only install keyboards from well-known developers with good reviews on official app stores.

✅ Read reviews: Before installing, carefully check app reviews to see if anyone mentions suspicious behavior.

✅ Be wary of overreaching permissions: Carefully consider the permissions requested by a keyboard before installing. If they seem excessive, don’t install them.

ℹ️ For more information on protecting yourself against this type of hack, check out our guide on detecting a keylogger on an iPhone.

5️⃣ Zero Day Exploits

A zero-day exploit is a cyberattack that takes advantage of a software vulnerability that device manufacturers or app developers don’t know about yet.

It’s called “zero-day” because the developers have zero days to fix the flaw before hackers can exploit it.

A famous example of a spyware app that uses Zero Day Exploits is Pegasus by the NSO Group.

Targeting both iPhones and Android devices, Pegasus is highly sophisticated spyware that could infect a phone through a simple missed call, text message, or by tricking the user into clicking a malicious link.

Once installed, it gives the attacker remote access to the infected device, allowing them to:

  • Monitor messages, calls, and emails
  • Access photos and videos
  • View location tracking
  • Activate the microphone and camera

Pegasus has been used by governments and organizations to target journalists, activists, and political figures.

Can it spy without your knowledge?

Zero-day exploits are incredibly sneaky, making it almost impossible to know if someone is spying on your phone.

However, being aware of suspicious activity can still provide clues, similar to signs of commercially available spyware.

⬆️ Go to section 1 for a refresher on the signs that your phone might be compromised.

How to protect yourself from a Zero-Day Exploit

Detecting zero-day exploits is very difficult, which is what makes them so dangerous. Therefore, prevention is the best form of protection. Here’s how:

✅ Keep everything updated: Install any operating system and app updates as soon as they’re released. These patch known vulnerabilities, reducing your attack surface.

✅ Strong security software: Use a reputable antivirus/anti-malware suite with real-time monitoring. While it might not catch the latest zero-days, it protects against many other threats.

✅ Enable Lockdown Mode: If you have an iPhone, turn on Lockdown Mode. This mode is specifically designed to block some zero-day attacks like Pegasus by restricting certain device features.

✅ Be careful online: Exercise caution when clicking links, opening attachments, or downloading files from untrusted sources.

Do you suspect a Zero-Day attack? Here’s what to do:

Taking swift action is crucial if you suspect your phone has been compromised by a zero-day exploit. Here’s how to proceed:

  1. Isolate your device: Disconnect it from the internet immediately. Turn off Wi-Fi and mobile data.
  2. Don’t panic, but act quickly: Zero-day exploits are serious, but keeping calm will help you take the necessary steps. Avoid excessive phone use, as this might allow the attacker to gather further data.
  3. Seek professional help: Contact a reputable IT security expert or specialized mobile security company. They can perform a thorough analysis to determine if there’s a zero-day compromise and guide you on removing it.
  4. Change passwords: While your phone is isolated, use a different secure device to immediately change passwords for critical accounts (email, banking, social media, etc.).
  5. Consider a factory reset: If a security expert confirms a zero-day compromise, the safest option might be a factory reset. This will erase all data, including the exploit.
  6. Report the incident: Consider reporting the potential exploit to the phone manufacturer and relevant authorities.

6️⃣ SIM card hacking

Another approach hackers use when spying on your phone is SIM card hacking or cloning. There are two different ways someone can hack your SIM card. We’ll discuss them below:

SIM swapping

The hacker convinces your mobile carrier they are you, often through social engineering (using personal information obtained through phishing or data leaks).

They then request that your phone number be transferred to a SIM card in their possession.

Once they control your number, they’ll receive calls and texts, including two-factor authentication codes. This makes it easier for hackers to access your bank accounts, social media, and more.

SIM cloning

Using specialized hardware and software, hackers copy the unique identifier of your SIM card onto a blank one. This creates a duplicate SIM that can make and receive calls/texts as if it were your phone.

Can it spy without your knowledge?

The good news is that it’s very easy to tell if your SIM card has been hacked or cloned. Here are the signs to look out for.

⚠️ Sudden loss of service: If you suddenly stop receiving calls and texts, it’s a major red flag. Contact your carrier immediately.

⚠️ Unrecognized outgoing calls: Check your bill for calls you didn’t make. This could indicate that someone is using your SIM.

⚠️ Suspicious restart requests: Be wary of texts asking you to restart your phone. Hackers may be trying to intercept your SIM data.

⚠️ Wrong location on device trackers: If your device appears in unexpected locations, your SIM may be compromised.

⚠️ Locked out of accounts: If you can’t access accounts using two-factor authentication codes sent via text, a hacker might have control of your SIM.

What to do if you suspect your SIM may be hacked

✅ Immediately report any suspicious activity to your mobile carrier. They can block the cloned SIM and issue you a new one.

✅ Change passwords for critical accounts (email, banking, etc.), especially if you suspect 2FA codes were intercepted.

✅ Monitor your bank accounts and report any unusual transactions.

💡 Pro-tip: Minimize physical access to your phone as much as possible, as physical cloning does require brief possession of your SIM card.

Key Takeaways

Modern smartphones are repositories of our personal lives, containing everything from photos and messages to banking and location data.

This makes them incredibly attractive targets for spying. While the thought of someone secretly monitoring you can be unsettling, there are certain steps you can take to improve your defenses.

Understanding the various ways hackers can exploit your phone is the first step. Regularly checking for the signs of spyware, keeping your software updated, and being cautious online are all crucial habits.

Remember, even the most sophisticated attacks often leave subtle clues.

If you do suspect something is amiss, don’t ignore it. Staying vigilant and proactive about your digital security is the key to safeguarding your privacy in today’s connected world.

Worried about spyware? Take control and scan your phone today with Certo.