Malware

Malware is a serious cyber threat all Victorians need to know about.

Malware is a type of software that cybercriminals use to damage your computer systems and steal information and money from you.

To stay safe from malware infections, the best strategy is to learn what they are, the warning signs and how to prevent them.

Keep reading to learn more.

What is malware?

Malware describes any type of software designed by cybercriminals to steal your information, your computer’s resources or your money.

The term is short for malicious software.

Common types of malware include ransomware, trojans, keyloggers, viruses, worms and adware.

Cybercriminals use malware to:

steal your information and account details
encrypt your data to get you to pay a ransom
install other software without your knowledge.

How does it work?

Your computer system or device can become infected with malware via:

spam email or messages (when you open a link or an attachment)
malicious websites you visit that try to install malware
weaknesses in your devices’ software
applications you downloaded and installed that you thought were trustworthy.

Once it infects your computer system or device, malware can spread to your programs and files and ‘corrupt’ them. This can cause:

your computer, programs and files to become very slow
access issues, because malware usually blocks your access to anything it has infected
your computer’s defences to weaken, making it easier for other harmful programs (like ransomware) to attack it.

How do I prevent malware?

Getting rid of malware can be a complicated process.

That’s why it’s best to focus on preventing it in the first place.

Below are some simple steps you can take to reduce the chances of a malware infection on your device:

Installing antivirus software is one of the best ways to protect yourself against malware. Antivirus software is a program designed to prevent, detect and remove viruses and other kinds of malware.
It’s important to keep the software up to date and use it to scan for viruses regularly.
If any viruses are detected, clean them up straight away.
If your antivirus software includes ransomware protection, make sure to enable it.
Top tip
Most operating systems already have antivirus software installed.
If you need to use a third party provider to purchase antivirus software, be careful as many are fake. For guidance on choosing and using antivirus software, refer to the Australian Cyber Security Centre’s website.
A 'macro' is a series of commands that automate a regular or repeated task in software, such as the Microsoft Office software suite. Macros are commonly used in MS Word and MS Excel.
Unless you need them, it’s safest to disable macros.
Malicious macros could allow malware, like ransomware, to access your computer. 
For example, when you open a document and it asks you if you want to enable editing, don't automatically say yes. If you’re not editing it, keep it in read-only view. If you need to edit it, make sure you trust where you got the document from before you enable any macros.
Visit Microsoft’s website to learn more about disabling macros.
Infected portable devices (like USBs) and malicious links can download malware onto your device.
Stay safe by following these tips:
- Don’t click on any web links or email attachments sent by anyone you don’t know.
- Don’t automatically click on links or attachments you receive, even if they’re from someone you know. If the sender is behaving in an odd way, they could be a cybercriminal pretending to be them. This is called phishing.
- Don’t allow images to download if you receive an email from an untrusted sender.
- Don’t download applications from third party sites.
- Don’t click on pop-up advertisements.
- Don’t open a file you’ve downloaded if it has a different file extension than what you were expecting. For example, if you were expecting a MS Word document or PDF, don’t click on a file that ends in .exe or .msi.
- Don’t pirate software, as it might not receive security updates or it could be malicious.
- Don’t use peer-to-peer file sharing, usually know as torrenting. Torrenting is used for downloading and sharing movies or games. Torrenting sites have been shown to host ransomware, so you could unintentionally download and/or share malicious files.
- Don't use any software that asks for excessive or suspicious permissions.
It’s also important to:
- contact a person directly if something doesn’t feel right. That way, you can confirm it’s really them you’re speaking to, and not someone pretending to be them
- use caution when using portable devices from others
- check that software is made by a reputable company before downloading and installing on your device
- always download software from the company’s official website or an official app store.

Top tip

If your system gets infected with malware, you’ll likely lose access to your files. By backing up your files regularly, you’ll be able to access a copy of your files even after a malware infection. Read our guide to backups to learn more.

Warning signs of malware

Below are the key warning signs your device may have a malware infection:

Malware warning sign	Examples
Unusual changes to your device	Your device has slowed down. Your device overheats. Your device's battery drains quickly. Your device runs its cooling fan faster than usual. All of these are warning signs that your processor has reached its limit (possibly because it’s running a malware program).
Unexpected files and programs on your device	You notice new programs, toolbars and icons have been installed.
You can't access your files	You try to open a file you opened the other day that now says it’s corrupted.
You receive ransom demands for the release of your files	You're contacted by a cybercriminal who demands you pay a ransom to get your files back.
Error messages	You keep seeing error messages on your device that you never used to see.
Unusual browser activity	Your web browser automatically takes you to a web page you didn’t mean to open.
Suspicious pop-up ads	You get pop-up ads about updating or downloading a program. You see ads claiming your computer has viruses or other technical problems.
Unusual account activity	Your account has been logged in from an odd location or at an odd time.
Your passwords have been changed	Your passwords have been changed even though you didn’t update them. You have trouble accessing your accounts.
Suspicious interactions	You're contacted by someone who says they know something about you that they could only have found out by accessing your device.

Top tip:

The Australian Cyber Security Centre’s resource, Have you been hacked?, provides additional guidance if you suspect your device has been compromised.

How do I get rid of malware?

Follow ACSC advice

How you get rid of malware will depend on which of your devices is infected. The Australian Cyber Security Centre’s malware guide provides helpful advice to detect and remove malware.

Seek professional help

If you’re having trouble getting rid of malware or you’re not very tech-savvy, get help from your IT support person or a local computer services company.

Make sure to do your research and contact a reputable company. Cybercriminals may pretend to be IT support and gain remote access to your computer. This would cause even more damage to your device and files.

Tips to protect your accounts

Malware can result in your personal and sensitive information being compromised. For example, if a keylogger records your keystrokes and steals your usernames and passwords as you type them in. Remember these tips for protecting your accounts:

use a different (non-infected) device to change passwords for your most important accounts
turn on multi-factor authentication (MFA)
be alert to potential scams
if you suspect the malware infection has compromised your identity documents or financial information, learn what to do after an information leak.

How do I report malware?

You can securely report malware (as well as other cybercrimes) to ReportCyber.

Your report will be referred directly to the relevant law enforcement agency.

By making a report, you will provide vital information to help target cybercriminals. You will also help to make going online more secure for all Australians.

Safety & emergencies

Updated 3 July 2024