How you can avoid downloading malicious code
6 min read
Whether for work, school, or entertainment, we constantly transfer files and download them to our devices. Most of those files contain the information we need. Unfortunately, some files contain malicious code that can harm your device and put private data at risk. Understanding how malicious code can get on a device and how to remove it will help to stay safe from this cybersecurity risk.
Table of Contents
Table of Contents
What is malicious code?
Malicious code is computer code designed to harm your computer or exploit an existing vulnerability. Sometimes, malicious code has an immediately noticeable effect on your computer or device. However, other times, it can go undetected and silently capture information like passwords or bank account information. In the context of malware, malicious code is the core component that enables malware to perform its harmful functions.
Different types of malware and malicious code vary in how they infiltrate your system and the actions they take once downloaded.
- Ransomware: Ransomware is a growing cybersecurity threat that encrypts your device’s data. Hackers typically demand payment, often in cryptocurrency, to decrypt the data and unlock your device.
- Spyware: Spyware installs itself on your device and then silently collects your passwords or other sensitive information. The spyware then sends the information back to the cybercriminals, who use it to access your accounts.
- Adware: Adware is a type of malicious code that modifies your web browsing experience by displaying ads or pop-ups.
- Trojan: A trojan is a computer program that appears to be a useful software tool. However, downloading and installing it can harm your computer, make your data vulnerable to theft, or activate ransomware.
- Virus: The bits of malicious code of a virus replicate across your devices and onto other devices. Viruses can perform many functions, including stealing passwords or redirecting you to malicious websites.
How you can avoid downloading malicious code
Malicious code can be dangerous, but thankfully, you can avoid it by knowing what to look for and taking simple precautions like the ones below.
Use comprehensive cyber threat solutions
Products like Threat Protection Pro™ from NordVPN automatically block ads, trackers, and malicious URLs. This feature also scans the files you download for malware and removes it if detected. These protection measures can keep you safe even if you let your guard down while browsing the internet.
Install a reputable antivirus solution
A dedicated antivirus solution is needed to deal with the constantly evolving threats from hackers. An antivirus solution will update itself automatically to detect the latest viruses. Antivirus software may also include a malware blocker. Furthermore, it can help you block pop-up ads that can be a source of malware or phishing links. While other cybersecurity solutions scan only new downloads, an antivirus can scan your device and detect malware that has already infected your device.
Keep your software up to date
Outdated software makes it much easier for malicious code to install itself on your computer. Make sure to turn on automatic updates for your operating system. If your software is no longer supported or getting updates, you should consider upgrading. If you use software that doesn’t allow you to enable automatic updates, check the vendor’s website to see if any upgrades or patches are available.
Don’t click on suspicious email links
A technique known as phishing is a common tactic for hackers to install malicious code on your system. They’ll send you an email that may look like it’s from someone you know and encourage you to click the included link. However, visiting such a link can initiate a download of malicious code on your device. To protect yourself from phishing emails and malicious links, you can use NordVPN’s free link checker. Simply copy and paste the link from the email into the link checker, and it will notify you if there’s any risk of malicious code.
For businesses, a phishing attack on one computer can quickly escalate into a wider cyberattack or data breach, compromising sensitive data, disrupting operations, and potentially causing financial and reputational damage to the entire organization. Recognizing phishing attempts — whether they contain harmful links or rely on social engineering tactics to extract information — is crucial for maintaining cybersecurity.
Use DNS filtering
DNS security techniques like filtering block access to sites that are not secure or are known to host malicious code. It can also mitigate the effects of DNS hijacking, which occurs when hackers redirect traffic from one site to a malicious site they control.
Be careful with free software
Some legitimate software companies offer free trials of their software. However, free versions of paid software offered on some websites or through advertisements are usually malware. This is especially true for cracked or pirated software. These programs will almost always contain some kind of malicious code. If you are using free software, make sure you are downloading it from the official vendor’s website.
Use a firewall
A firewall acts as a barrier to block unauthorized access to your computer. Most computers have a free firewall as part of the operating system, but don’t forget to check if your firewall is active.
On Windows:
- Select the “Start menu.”
- Click on “Settings.”
- Click “Privacy and security.”
- Click “Windows security.”
- Click “Firewall and network protection.” If it isn’t already on, select the option to turn it on.
On Mac:
- Choose the “Apple menu.”
- Click “System settings.”
- Click “Network” and select “Firewall.”
Don’t visit unsecured websites
An unsecured website doesn’t use encryption to hide data as it moves between you and the website. You can check if the website is secure by looking at the URL in your browser. It should start with “https://.” If it’s missing the “s,” it is not secure and is a risk. Legitimate websites will almost always display the “s,” so if that’s missing, be wary of using that website.
Create unique passwords
Make sure you create strong passwords that are unique for each service you access. A password can’t prevent malicious code, but it can limit the attacker from compromising your other accounts if they all share the same weak password.
How can malicious code cause damage?
Malicious code can damage your devices and finances in several ways. With ransomware, the malicious code completely locks you out of your device.
With other types of malicious code, your personal passwords or banking information can be stolen. Thieves can drain your bank accounts, leaving you in financial distress as you try to restore your lost funds with your bank or credit card company.
How can you tell if your system is infected with malicious code?
Sometimes, the symptoms of an infected device are obvious, such as with a ransomware attack, while at other times, they are subtle. Below are some signs you may have malicious code on your device.
- You notice a sudden decrease in performance or spikes in CPU or memory use.
- You see unusual pop-up windows when browsing the internet or just using your device.
- Your bookmarks and homepage have changed.
- Pop-ups are telling you your system is infected or displaying advertisements.
- New programs or icons were added to your desktop that you did not install.
- You’re unable to access certain settings on your system.
How to remove malicious code from the system
If you notice any strange behavior with your system, it’s important to run a full antivirus or anti-malware scan. Most antivirus programs offer both quick and full scan options, but a full scan is more thorough and can sometimes detect malicious code that quick scans might miss.
Make sure you have antivirus software installed. If not, you can choose and install one to run the necessary scan. During the process, if the software detects any threats, it will prompt you with options to remove them. Simply follow the on-screen instructions to eliminate the malicious code.
Use safe mode
On Windows computers, malicious code may prevent you from starting or using your computer normally. Starting in safe mode may allow you to access the system and run an antivirus scan.
Check your system’s documentation for instructions on how to boot into safe mode, as this can differ by manufacturer. You can usually find this information on the manufacturer’s website or through online support resources. On most computers, you can try holding down the F4, F8, or F11 keys while turning on the computer to start in safe mode. Once in safe mode, you can install a new antivirus program or run your existing antivirus software to scan for threats.
Perform a system backup
Windows computers have restore points, which are a type of system backup. To access them, go to the Control Panel, search for “System Restore,” and follow the prompts to choose a restore point from before the malicious code was introduced. On Macs, you can use the Time Machine app to create and restore backups. Simply open Time Machine, select a backup from before the infection occurred, and restore your system to that state.
Reinstall your operating system
Sometimes, you may need to perform a clean reinstallation of the operating system, which will restore your system to factory settings and should remove any malicious code. However, it’s important to try other recovery methods first, as a clean reinstall can result in the loss of any unsaved data. For instructions on how to do this, you can refer to the official support website for your operating system—such as Microsoft’s support page for Windows or Apple’s support page for macOS—or consult user manuals and online tutorials.
Be aware of how malicious code can infect your system
The best defense against malicious code is knowing how it can be downloaded onto your computer. Whenever you’re checking an email, visiting a new website, or downloading a software program, take a moment to pause. Ask yourself if anything about the links or website seems suspicious or matches the signs outlined in this guide.
If you have any suspicions, it’s best not to click the link or download the file until you can confirm it’s safe. Use a link checker or confirm the website is legitimate before continuing. Taking a few seconds to check can save you hours or even days of headaches from accidentally downloading malicious code.