What is Zero-Click Malware? How It Works & How to Avoid It

When it comes to malware, people tend to think of the most commonly known threats, like worms, trojans and ransomware. 

What some internet users may not know, however, is that there’s been a surge in zero-click cyber attacks, a lesser known variety which requires no user interaction to install itself.

But what exactly is zero-day malware? Let’s explore the most common types, how they operate, and most importantly, how you can protect yourself against them.

What is Zero-Click Malware?

Zero-click malware takes advantage of vulnerabilities in software, and arguably poses a greater threat as it can independently install itself on a system without user interaction.

This unique characteristic separates it from traditional forms of malware which usually rely on some form of social engineering that leads to the user unknowingly clicking malicious links and installing harmful files.

And so, the term ‘zero-click’ really couldn’t be more fitting for this type of malware as it can independently ready itself to compromise a targeted computer, smartphone or tablet (for the purpose of stealing critical data, for instance).

Also referred to as ‘zero-click attacks’ and ‘zero-click exploits’, zero click malware often employs sophisticated tactics, and is renowned for being startlingly proficient in remaining undetected, operating quietly in the background.

Since zero-click attacks target unpatched software flaws and leave very little trace of malicious activity, they can be incredibly difficult for everyday users – and even cyber security experts – to detect, identify and remove.

How Does Zero-Click Malware Work?

Since zero-click attacks don’t rely on phishing tactics to provide hackers with an entry point, they must make use of data verification loopholes in order to infect systems.

In other words, they are purposed to exploit flaws in a device’s software and can achieve malicious code execution independently, which then allows for malware to be installed.

Despite most software using data verification processes to defend against cyber breaches, there are always zero-day vulnerabilities yet to be patched. Once identified, hackers can exploit these flaws to execute user-interaction-free attacks.

Common Types of Zero-Click Exploits

The majority of zero-click attacks are developed to target vulnerabilities in applications that provide a messaging or voice calling service, the reason being that these apps can accept and process data from untrusted sources.

SMS/messaging platforms, along with email and other smartphone apps, receive data from untrusted sources and interpret it before displaying it to the device user. 

By using specially formed data, such as carefully crafted messages or image files, hackers can take advantage of unpatched data processing code vulnerabilities by injecting malicious code capable of compromising a device. 

The reason this form of cyber attack is coveted so highly by hackers is obvious: the receiving of data like SMS and email does not require user interaction, and smartphone users receive notifications of their contents before opening them.

Sophisticated hackers can send maliciously-crafted messages capable of not simply installing malware, but also disabling notifications, meaning the user could be totally unaware that a zero-click attack has compromised their device.

Attackers may seek to exploit vulnerabilities (in the code of an app tasked with processing incoming data) by using harmful content including text messages, MMS, voicemail, phone calls, WhatsApp, Telegram and Skype messages, network packets and authentication requests.

The consequences of a successful zero-click attack against a mail or messaging vulnerability could include hackers remotely reading and stealing personal information within messages, and also editing and deleting messages.

Who Does Zero-Click Malware Target?

Zero-click attacks can strike and compromise any internet-connected device, including desktops, tablets and smartphones, and are much-feared due to their alarming ability to execute illicit tasks while remaining largely undetectable.

In reality, just about anyone could become the target of zero-click attacks, which are commonly deployed by cyber criminals to gather personal, financial, and even highly sensitive national security-related data, using covertly installed spyware. 

So anyone, from personal users, to business tycoons and politicians, could be targeted, especially since smartphone apps that provide message/voice calling services accept and process data from untrusted sources (see above).

How to Protect Your Devices from Zero-Click Malware

Zero-click attacks pose a uniquely serious threat to computers and smart devices as they require no user action, target zero-day exploits, and can be incredibly difficult to detect. 

But that doesn’t mean a strong cyber security plan can’t be implemented to help protect your personal data. Here are several preventative steps everyone can take to maximize their chances of evading a zero-click attack:

• Update Software: Since zero-click exploits seek out unpatched software vulnerabilities, it’s crucial that you don’t neglect or delay installing the latest updates for your devices’ operating systems and apps
• Use AntiVirus Protection: Nowadays, having AntiVirus is absolutely essential; the Award-Winning TotalAV checks files, installs and executables at point of download and access, and not only uses a database to instantly identify known threats, but also advanced cloud scanning technology (by analyzing system and file behaviours) to block and remove unknown zero-day infections
• Block Pop-Ups: As cyber criminals commonly use pop-ups to spread malware, it’s also recommended that you take advantage of a pop-up blocker, such as Total AdBlock, to clean up your browser and increase privacy
• Avoid Unsafe App Stores: Apps from third-party stores and websites (particularly those distributing pirated/free versions of software, games and add-ons, etc) can contain malicious code, so always stick to trusted platforms like the official Android, Apple or Microsoft app stores; read reviews, listen to your gut, and beware of any suspicious activity or unusual permission requests
• Avoid Jailbroken Devices: The term ‘jailbroken’ refers to devices (usually smartphones) that have had their critical software protections removed; while this can allow for free/pirate apps to be installed, these devices are inherently more susceptible to malware
• Bruk sterke passord: Always use strong, unique passwords to protect your devices, online accounts and networks, and take advantage of MFA (Multi-Factor Authentication) where possible to add an extra layer of security; tools like Totalt passord can optimize the login process by securely creating and storing strong passwords (inside an encrypted vault) for you
• Uninstall Old Apps: Every app on your device technically makes it more susceptible to attack, so be sure to delete any superfluous apps collecting digital dust
• Backup Regularly: Make it a top priority to create a regular backup schedule; this way, you’ll be able to more quickly recover from, for instance, a zero-click attack which has covertly installed system-locking ransomware