What is Malware?

Malware defined and explained

Malware, or “malicious software,” is an umbrella term that describes any malicious program or code that is harmful to systems.

Hostile, intrusive, and intentionally nasty, malware seeks to invade, damage, or disable computers, computer systems, networks, tablets, and mobile devices, often by taking partial control over a device’s operations. Like the human flu, it interferes with normal functioning.

The motives behind malware vary. Malware can be about making money off you, sabotaging your ability to get work done, making a political statement, or just bragging rights. Although malware cannot damage the physical hardware of systems or network equipment, it can steal, encrypt, or delete your data, alter or hijack core computer functions, and spy on your computer activity without your knowledge or permission.




How can I tell if I have a malware infection?


Malware can reveal itself with many different aberrant behaviors. Here are a few telltale signs that you have malware on your system:
Your computer slows down. One of malware’s side effects is to reduce the speed of your operating system (OS), whether you’re navigating the Internet or just using your local applications, usage of your system’s resources appears abnormally high. You might even notice your computer’s fan whirring away at full speed—a good indicator that something is taking up system resources in the background. This tends to happen when your computer has been roped into a botnet; i.e. a network of enslaved computers used to perform DDoS attacks, blast out spam, or mine cryptocurrency.
Your screen is inundated with annoying ads. Unexpected pop-up ads are a typical sign of a malware infection. They’re especially associated with a form of malware known as adware. What’s more, pop-ups usually come packaged with other hidden malware threats. So if you see something akin to “CONGRATULATIONS, YOU’VE WON A FREE PSYCHIC READING!” in a pop-up, don’t click on it. Whatever free prize the ad promises, it will cost you plenty.
Your system crashes. This can come as a freeze or a BSOD (Blue Screen of Death), the latter occurs on Windows systems after encountering a fatal error.
You notice a mysterious loss of disk space. This could be due to a bloated malware squatter, hiding in your hard drive aka bundleware.
There’s a weird increase in your system’s Internet activity. Take Trojans for example. Once a Trojan lands on a target computer, the next thing it does is reach out to the attacker’s command and control server (C&C) to download a secondary infection, often ransomware. This could explain the spike in Internet activity. The same goes for botnets, spyware, and any other threat that requires back and forth communication with the C&C servers.
Your browser settings change. If you notice your homepage changed or you have new toolbars, extensions, or plugins installed, then you might have some sort of malware infection. Causes vary, but this usually means you clicked on that “congratulations” pop-up, which downloaded some unwanted software.
Your antivirus product stops working and you cannot turn it back on, leaving you unprotected against the sneaky malware that disabled it.
You lose access to your files or your entire computer. This is symptomatic of a ransomware infection. The hackers announce themselves by leaving a ransom note on your desktop or changing your desktop wallpaper itself in to a ransom note (see GandCrab). In the note, the perpetrators typically inform you that your data has been encrypted and demand a ransom payment in exchange for decrypting your files.
Even if everything seems to be working just fine on your system, don’t get complacent, because no news isn’t necessarily good news. Powerful malware can hide deep in your computer, evading detection, and going about its dirty business without raising any red flags. While we’ve provided a quick malware spotter’s guide, it really takes the unfaltering eye of a good cybersecurity program to detect malware on your system (more on that later).

How do I get malware?
The two most common ways that malware accesses your system are the Internet and email. So basically, anytime you’re connected online, you’re vulnerable.

Malware can penetrate your computer when (deep breath now) you surf through hacked websites, view a legitimate site serving malicious ads, download infected files, install programs or apps from unfamiliar provide, open a malicious email attachment (malspam), or pretty much everything else you download from the web on to a device that lacks a quality anti-malware security application.

Malicious apps can hide in seemingly legitimate applications, especially when they are downloaded from websites or direct links (in an email, text, or chat message) instead of an official app store. Here it’s important to look at the warning messages when installing applications, especially if they seek permission to access your email or other personal information.

“Malware attacks would not work without the most important ingredient: you.”

Bottom line, it’s best to stick to trusted sources for mobile apps, only installing reputable third-party apps, and always downloading those apps directly from the vendor—and never from any other site. All in all, there is a world of bad actors out there, throwing tainted bait at you with an offer for an Internet accelerator, new download manager, hard disk drive cleaner, or an alternative web search service.

Malware attacks would not work without the most important ingredient: you. That is, a gullible version of you, willing to open up an email attachment you don’t recognize, or to click and install something from an untrustworthy source. And don’t take this as “click-shaming,” because even very experienced people have been tricked into installing malware.

Even if you install something from a credible source, if you don’t pay attention to the permission request to install other bundled software at the same time, you could be installing software you don’t want. This extra software, also known as a potentially unwanted program (PUP), is often presented as a necessary component, but it often isn’t.

Another wrinkle is a bit of social engineering that a Malwarebytes expert observed in the UK. The scam hit mobile users by taking advantage of a common mobile direct-to-bill payment option. Users visited mobile sites, unwittingly tripping invisible buttons that charge them via their mobile numbers, directly billing the victims’ networks, which pass the cost onto their bill.

To be fair, we should also include a blameless malware infection scenario. Because it’s even possible that just visiting a malicious website and viewing an infected page and/or banner ad will result in a drive-by malware download. Malware distributed via bad ads on legitimate websites is known as malvertising.

On the other hand, if you’re not running an adequate security program, the malware infection and its aftermath are still on you.

What are the most common forms of malware?
Here are the most common offenders in the rogues’ gallery of malware:

Adware is unwanted software designed to throw advertisements up on your screen, most often within a web browser. Typically, it uses an underhanded method to either disguise itself as legitimate, or piggyback on another program to trick you into installing it on your PC, tablet, or mobile device.
Spyware is malware that secretly observes the computer user’s activities without permission and reports it to the software’s author.
A virus is malware that attaches to another program and, when executed—usually inadvertently by the user—replicates itself by modifying other computer programs and infecting them with its own bits of code.
Worms are a type of malware similar to viruses. Like viruses, worms are self-replicating. The big difference is that worms can spread across systems on their own, whereas viruses need some sort of action from a user in order to initiate the infection.
A Trojan, or Trojan horse, is one of the most dangerous malware types. It usually represents itself as something useful in order to trick you. Once it’s on your system, the attackers behind the Trojan gain unauthorized access to the affected computer. From there, Trojans can be used to steal financial information or install other forms of malware, often ransomware.
Ransomware is a form of malware that locks you out of your device and/or encrypts your files, then forces you to pay a ransom to regain access. Ransomware has been called the cybercriminal’s weapon of choice because it demands a quick, profitable payment in hard-to-trace cryptocurrency. The code behind ransomware is easy to obtain through online criminal marketplaces and defending against it is very difficult. While ransomware attacks on individual consumers are down at the moment, attacks on businesses are up 365 percent for 2019. As an example, the Ryuk ransomware specifically targets high-profile organizations that are more likely to pay out large ransoms. For more, check out the Malwarebytes Labs Ransomware Retrospective.
Rootkit is a form of malware that provides the attacker with administrator privileges on the infected system, also known as “root” access. Typically, it is also designed to stay hidden from the user, other software on the system, and the operating system itself.
A keylogger is malware that records all the user’s keystrokes on the keyboard, typically storing the gathered information and sending it to the attacker, who is seeking sensitive information like usernames, passwords, or credit card details.
Malicious cryptomining, also sometimes called drive-by mining or cryptojacking, is an increasingly prevalent malware usually installed by a Trojan. It allows someone else to use your computer to mine cryptocurrency like Bitcoin or Monero. So instead of letting you cash in on your own computer’s horsepower, the cryptominers send the collected coins into their own account and not yours. Essentially, a malicious cryptominer is stealing your resources to make money.
Exploits are a type of malware that takes advantage of bugs and vulnerabilities in a system in order to give the attacker access to your system. While there, the attacker might steal your data or drop some form of malware. A zero-day exploit refers to a software vulnerability for which there is currently no available defense or fix.