Your smartphone holds intimate details about your life. Banking passwords, private messages, location data, photos you've never shared, emails from your doctor or lawyer. If someone gains unauthorised access to your phone, they can potentially steal your identity, monitor your movements, or drain your bank account. Yet many people wouldn't recognise the warning signs of compromise until serious damage has already occurred.
The reality is that phone hacking is no longer a threat confined to high-profile figures or large organisations. A 2025 cybersecurity report from mobile security provider Zimperium found that 18.1% of all devices had malware installed. For Australian smartphone users, understanding the visible signs of compromise is now an essential part of digital hygiene.
Battery Life and Device Performance
According to cybersecurity expert Akash Mahajan, one of the biggest warning signs your gadgets could be compromised is sudden and unexplained battery drain. This happens because malicious software running quietly in the background can cause a rapidly draining battery. If your phone's battery life has shortened noticeably without any change in how you use it, that's worth investigating.
Similarly, if your phone has suddenly become sluggish, freezing, or crashing frequently, it may be due to malicious software running in the background, as hackers often install spyware or malware that consumes your phone's processing power, leading to noticeable slowdowns. Performance degradation isn't always a sign of hacking, but when it coincides with other unusual behaviour, it warrants caution.
Unwanted Apps and Pop-ups
Finding apps you never installed is one of the clearest signs of compromise; hackers often install additional tools remotely to strengthen control over the device. These apps may disguise themselves as system services or utilities to avoid suspicion. Take time regularly to review what's installed on your phone and remove anything unfamiliar.
Pop-up advertisements represent another visual clue. Random pop-ups, especially ones urging you to click suspicious links or download apps, are a major red flag, as these could be signs of adware, a type of malware designed to bombard you with intrusive advertisements and collect your data.
Unusual Activity and Data Usage
If friends or contacts report receiving strange messages, links, or OTP requests from your number, your device may be compromised. Hackers often use malware to send phishing messages or spam from your device without your knowledge. Similarly, a hacked Android phone frequently sends collected data to external servers, leading to abnormal mobile data consumption even when you're not streaming or browsing.
Using Dial Codes for Detection
Several special dial codes can reveal whether your phone is being tampered with. Dial *#21#: This code shows you the status of call forwarding; if calls, messages, or other data are being diverted without your knowledge, this is one of the key signs your phone is hacked. The results should all say "Not Forwarded." Dial *#62# to find out where calls are being forwarded when your phone is unreachable (e.g., turned off or out of service area); it should typically go to your carrier's voicemail number, so check if the number shown is unfamiliar. Dial ##002#, a universal code that disables all call forwarding; if you suspect your calls are being diverted, dialing this code will reset it. However, these codes show if your calls and messages are being forwarded, which can be a sign of a hack, but they don't detect other types of malware or spyware.
What to Do If You Suspect Compromise
If multiple warning signs appear, act quickly. The first thing to do is disconnect your phone from the internet, turning on airplane mode and disabling Wi-Fi and Bluetooth to stop hackers from continuing to communicate with the device. Next, run a security scan using a trusted mobile security app from the official app store; these tools can detect suspicious software and help remove potential threats.
It's also a good idea to change important passwords such as email, banking, and social media accounts, ideally from a different device you know is secure; enabling multi-factor authentication can add another layer of protection. Avoid changing passwords from the potentially compromised device itself, as a keylogger could capture your new credentials.
In most cases, a factory reset erases all data and apps on your device, including most forms of malware and spyware, returning it to its original state. This is a last resort that will erase everything, so back up important files first.
Prevention Over Cure
The most effective defence remains prevention. Most Android phones are compromised through human error rather than system flaws; installing apps from unknown sources, clicking phishing links, connecting to unsafe public Wi-Fi, or ignoring security updates are the most common entry points. Keep your operating system and apps updated, download only from official app stores, and be sceptical of unexpected links in messages or emails.
Phone security isn't about paranoia; it's about recognising that your device contains the keys to your financial, professional, and personal life. Knowing these warning signs and responding promptly can prevent the kind of damage that leaves victims spending months restoring their digital lives.