Types Of Malware In Computer


What is Malware?

As software designed to interfere with a computer’s normal functioning, malware is a blanket term for viruses, trojans, and other destructive computer programs threat actors use to infect systems and networks in order to gain access to sensitive information.

Malware (short for “malicious software”) is a file or code, typically delivered over a network, that infects, explores, steals or conducts virtually any behavior an attacker wants. And because malware comes in so many variants, there are numerous methods to infect computer systems. Though varied in type and capabilities, malware usually has one of the following objectives:

  • Provide remote control for an attacker to use an infected machine.
  • Send spam from the infected machine to unsuspecting targets.
  • Investigate the infected user’s local network.
  • Steal sensitive data.

Malware is intrusive software that is designed to damage and destroy computers and computer systems. Malware is a contraction for “malicious software.” Examples of common malware includes viruses, worms, Trojan viruses, spyware, adware, and ransomware.

Malware, short for “malicious software,” refers to any intrusive software developed by cybercriminals (often called “hackers”) to steal data and damage or destroy computers and computer systems. Examples of common malware include viruses, worms, Trojan viruses, spyware, adware, and ransomware. Recent malware attacks have exfiltrated data in mass amounts.


Ransomware – Is a criminal business model that uses malicious software to hold valuable files, data or information for ransom. Victims of a ransomware attack may have their operations severely degraded or shut down entirely.

Remote Administration Tools (RATs) – Software that allows a remote operator to control a system. These tools were originally built for legitimate use, but are now used by threat actors. RATs enable administrative control, allowing an attacker to do almost anything on an infected computer. They are difficult to detect, as they don’t typically show up in lists of running programs or tasks, and their actions are often mistaken for the actions of legitimate programs.

Rootkits – Programs that provide privileged (root-level) access to a computer. Rootkits vary and hide themselves in the operating system.

Spyware – Malware that collects information about the usage of the infected computer and communicates it back to the attacker. The term includes botnets, adware, backdoor behavior, keyloggers, data theft and net-worms.

Trojans Malware – Malware disguised in what appears to be legitimate software. Once activated, malware Trojans will conduct whatever action they have been programmed to carry out. Unlike viruses and worms, Trojans do not replicate or reproduce through infection. “Trojan” alludes to the mythological story of Greek soldiers hidden inside a wooden horse that was given to the enemy city of Troy.

Virus Malware – Programs that copy themselves throughout a computer or network. Malware viruses piggyback on existing programs and can only be activated when a user opens the program. At their worst, viruses can corrupt or delete data, use the user’s email to spread, or erase everything on a hard disk.

Worm Malware – Self-replicating viruses that exploit security vulnerabilities to automatically spread themselves across computers and networks. Unlike many viruses, malware worms do not attach to existing programs or alter files. They typically go unnoticed until replication reaches a scale that consumes significant system resources or network bandwidth.

Botnet– Short for “robot network,” these are networks of infected computers under the control of single attacking parties using command-and-control servers. Botnets are highly versatile and adaptable, able to maintain resilience through redundant servers and by using infected computers to relay traffic. Botnets are often the armies behind today’s distributed denial of service attacks.

Cryptojacking – is malicious cryptomining (the process of using computing power to verify transactions on a blockchain network and earning cryptocurrency for providing that service) that happens when cybercriminals hack into both business and personal computers, laptops, and mobile devices to install software.

Malvertising – Malvertising is a portmanteau of “malware + advertising” describing the practice of online advertising to spread malware. It typically involves injecting malicious code or malware-laden advertisements into legitimate online advertising networks and webpages.

Polymorphic malware – Any of the above types of malware with the capacity to “morph” regularly, altering the appearance of the code while retaining the algorithm within. The alteration of the surface appearance of the software subverts detection via traditional virus signatures.

Viruses are a subgroup of malware. A virus is malicious software attached to a document or file that supports macros to execute its code and spread from host to host. Once downloaded, the virus will lay dormant until the file is opened and in use. Viruses are designed to disrupt a system’s ability to operate. As a result, viruses can cause significant operational issues and data loss.


Worms are a malicious software that rapidly replicates and spreads to any device within the network. Unlike viruses, worms do not need host programs to disseminate. A worm infects a device via a downloaded file or a network connection before it multiplies and disperses at an exponential rate. Like viruses, worms can severely disrupt the operations of a device and cause data loss.

Trojan virus

Trojan viruses are disguised as helpful software programs. But once the user downloads it, the Trojan virus can gain access to sensitive data and then modify, block, or delete the data. This can be extremely harmful to the performance of the device. Unlike normal viruses and worms, Trojan viruses are not designed to self-replicate.


Spyware is malicious software that runs secretly on a computer and reports back to a remote user. Rather than simply disrupting a device’s operations, spyware targets sensitive information and can grant remote access to predators. Spyware is often used to steal financial or personal information. A specific type of spyware is a keylogger, which records your keystrokes to reveal passwords and personal information.


Adware is malicious software used to collect data on your computer usage and provide appropriate advertisements to you. While adware is not always dangerous, in some cases adware can cause issues for your system. Adware can redirect your browser to unsafe sites, and it can even contain Trojan horses and spyware. Additionally, significant levels of adware can slow down your system noticeably. Because not all adware is malicious, it is important to have protection that constantly and intelligently scans these programs.

Fileless malware

Fileless malware is a type of memory-resident malware. As the term suggests, it is malware that operates from a victim’s computer’s memory, not from files on the hard drive. Because there are no files to scan, it is harder to detect than traditional malware. It also makes forensics more difficult because the malware disappears when the victim computer is rebooted. In late 2017, the Cisco Talos threat intelligence team posted an example of fileless malware that they called DNSMessenger.

Types of Malware Attacks

Malware also uses a variety of methods to spread itself to other computer systems beyond an initial attack vector. Malware attack definitions can include:

  • Email attachments containing malicious code can be opened, and therefore executed by unsuspecting users. If those emails are forwarded, the malware can spread even deeper into an organization, further compromising a network.
  • File servers, such as those based on common Internet file system (SMB/CIFS) and network file system (NFS), can enable malware to spread quickly as users access and download infected files.
  • File-sharing software can allow malware to replicate itself onto removable media and then on to computer systems and networks.
  • Peer to peer (P2P) file sharing can introduce malware by sharing files as seemingly harmless as music or pictures.
  • Remotely exploitable vulnerabilities can enable a hacker to access systems regardless of geographic location with little or no need for involvement by a computer user.

Malware Detection:

Advanced malware analysis and detection tools exist such as firewalls, Intrusion Prevention Systems (IPS), and sandboxing solutions. Some malware types are easier to detect, such as ransomware, which makes itself known immediately upon encrypting your files. Other malware like spyware, may remain on a target system silently to allow an adversary to maintain access to the system. Regardless of the malware type or malware meaning, its detectability or the person deploying it, the intent of malware use is always malicious.

When you enable behavioral threat protection in your endpoint security policy, the Cortex XDR agent can also continuously monitor endpoint activity for malicious event chains identified by Palo Alto Networks.

Malware Removal:

Antivirus software can remove most standard infection types and many options exist for off-the-shelf solutions. Cortex XDR enables remediation on the endpoint following an alert or investigation giving administrators the option to begin a variety of mitigation steps starting with isolating endpoints by disabling all network access on compromised endpoints except for traffic to the Cortex XDR console, terminating processes to stop any running malware from continuing to perform malicious activity on the endpoint, and blocking additional executions, before quarantining malicious files and removing them from their working directories if the Cortex XDR agent has not already done so

How do I protect my network against malware?

Typically, businesses focus on preventative tools to stop breaches. By securing the perimeter, businesses assume they are safe. Some advanced malware, however, will eventually make their way into your network. As a result, it is crucial to deploy technologies that continually monitor and detect malware that has evaded perimeter defenses. Sufficient advanced malware protection requires multiple layers of safeguards along with high-level network visibility and intelligence.

How do I detect and respond to malware?

Malware will inevitably penetrate your network. You must have defenses that provide significant visibility and breach detection. In order to remove malware, you must be able to identify malicious actors quickly. This requires constant network scanning. Once the threat is identified, you must remove the malware from your network. Today’s antivirus products are not enough to protect against advanced cyber threats.

What are the benefits of advanced malware protection?

Advanced malware can take the form of common malware that has been modified to increase its capability to infect. It can also test for conditions of a sandbox meant to block malicious files, and attempt to fool security software into signaling that it is not malware. Advanced malware protection software is designed to prevent, detect, and help remove threats in an efficient manner from computer system. 

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