Malware
Any software intentionally designed to damage, disrupt, or gain unauthorized access to a device or network.
Definition
Malware, short for malicious software, is any program or code created with the intent to harm a computer system, steal data, or gain unauthorized access without the owner's consent. It is an umbrella term covering viruses, worms, trojans, ransomware, spyware, and keyloggers, each with a different method of infection and objective.
Malware most commonly reaches a device through a phishing email attachment, a malicious link, an infected removable drive, or a bundled download from an untrustworthy website. Once executed, it may replicate itself, encrypt files for ransom, silently monitor activity, or open a backdoor that lets an attacker return later. Modern malware is often modular, downloading additional malicious components after the initial infection to expand what it can do on the compromised device.
Malware matters because a single infected endpoint can serve as an entry point into an entire corporate network, especially in flat network environments common in smaller organizations. For regulated sectors such as banking in Indonesia, a malware infection that reaches core systems can trigger significant regulatory reporting obligations and reputational damage. The financial cost extends beyond remediation to include potential data breach notification, downtime, and in the case of ransomware, extortion demands.
Layered defense is essential: up to date endpoint protection, email filtering, network segmentation, and regular patching each close a different avenue malware can use to spread. Employees remain a critical line of defense because most infections still begin with a human action, such as opening an attachment or enabling macros, so recognizing suspicious files and links reduces the chance of infection. Regular backups that are tested and kept offline or immutable ensure that even a successful infection does not become an unrecoverable data loss event.
At a glance
- Severity
- High
- Prevalence
- Very common
- Primary targets
- Any connected device, across organizations of every size
- Also known as
- Malicious software
How it works
- 1
Delivery: malware reaches a device through a phishing attachment, malicious link, infected removable drive, or bundled download.
- 2
Execution: once opened or run, the malicious code begins carrying out its designed function.
- 3
Action: it may replicate itself, encrypt files for ransom, silently monitor activity, or open a backdoor for later access.
- 4
Expansion: modern malware is often modular, downloading additional malicious components after the initial infection.
- 5
Impact: a single infected endpoint can become an entry point into the wider corporate network.
Warning signs
- Unexpected pop-ups, slow performance, or unfamiliar programs running
- Files that suddenly become encrypted or inaccessible
- Security software disabled or alerts you did not trigger
- Unusual network activity or data usage from a device
- An attachment or download that prompted you to enable macros or bypass a warning
How to defend
- Keep endpoint protection and operating systems up to date
- Use email filtering and be cautious with unexpected attachments or links
- Segment networks so an infection cannot spread freely
- Apply security patches promptly to close known vulnerabilities
- Maintain tested, offline or immutable backups so an infection does not become unrecoverable data loss
Real-world example
An employee at an Indonesian logistics company opens an email attachment disguised as a shipping manifest. The file silently installs malware that spreads across the internal network overnight, encrypting files on multiple servers before the security team detects the activity the next morning.
How Claro helps
Claro's phishing simulations use realistic malicious attachment and link scenarios so employees practice recognizing the delivery methods attackers use to install malware, without any real malicious payload.
Frequently asked questions
What is Malware?
Malware, short for malicious software, is any program or code deliberately built to damage a system, steal data, or gain unauthorised access. It is an umbrella term covering viruses, ransomware, spyware, trojans, and worms.
What is the difference between malware and a virus?
A virus is one specific type of malware that replicates itself by attaching to other files. Malware is the umbrella term covering viruses, worms, trojans, ransomware, spyware, and keyloggers, each with a different method and objective.
How does malware most commonly infect a device?
Most infections begin with a human action, such as opening a phishing attachment, clicking a malicious link, enabling macros, or plugging in an infected removable drive.
Can antivirus software stop all malware?
No single tool catches everything, especially newly created malware without a known signature. Layered defenses, endpoint protection, patching, network segmentation, and trained employees, together reduce the risk far more effectively.
What should I do if I suspect a device is infected?
Disconnect it from the network immediately, report it to your security team, and avoid using it until it has been scanned and cleared, since a connected infected device can spread to others.
Related terms
Ransomware
Malware that encrypts an organisation's files or locks its systems, then demands a payment to restore access.
Spyware
Software that secretly monitors a user's activity and collects information such as browsing habits, keystrokes, or credentials without consent.
Keylogger
A type of spyware that records every keystroke a user types, capturing passwords, messages, and other sensitive input.
Phishing
Phishing is a social engineering attack where criminals impersonate a trusted sender to trick people into revealing credentials, transferring money, or installing malware.
Reduce your human risk
Claro measures and lowers the risk these terms describe, in English and Bahasa Indonesia.
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