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Malware
Software built to damage systems, steal data or give an attacker control.
What it means
Malware, short for malicious software, is any program designed to harm a system, steal data, spy on people or let someone else take control. Viruses, worms, trojans, spyware, ransomware and backdoors are all kinds of malware. The common thread is that it runs without the owner's informed consent.
What separates it from a bug is intent. A bug is a mistake in code that someone wrote in good faith. Malware is written to do damage, and it often hides itself, so it can stay on a machine for a long time.
Why it matters
Malware turns a single mistake into a long-term problem. One infected laptop can leak sign-in details that open your cloud accounts. One poisoned package can reach every customer who installs your product, which is how a supply chain attack works.
The business costs include downtime, clean-up, the legal duties after a data breach, and lost trust. For a software company, a compromised build or developer machine is especially serious because the damage spreads outward to customers. Treat build systems and developer laptops with extra care.
How it shows up
Malware arrives as email attachments, links to fake download pages, infected installers, malicious packages published to public registries, browser extensions, uploaded files, and through unpatched software. Web applications meet it in file upload features, where a user can submit something that your server then stores or serves to others.
Check the places your business takes in outside files and code. Scan uploads, restrict file types, store them away from your executable paths, and verify dependencies before you add them. Keep devices patched and use endpoint detection. Assume some will get through and make sure you can spot and isolate it quickly.
Questions people ask
Malware, answered
What are the main types of malware?
Viruses and worms spread; trojans pretend to be useful software; spyware watches; ransomware locks data for payment; backdoors give remote access; and loaders download further malware.
Many samples combine several of these behaviours.
Is antivirus enough?
It helps against known samples but misses new or customised ones. Modern tools also watch behaviour on the machine.
Add patching, least privilege, backups and fast response. No single layer is enough.
Can a web application spread malware?
Yes. If users can upload files that others download, or if your site is modified to serve malicious scripts, your app becomes the delivery route.
Scan uploads and protect the code and the build pipeline.
How does malware get past defences?
Often through the user: a convincing email, a fake update, a pirated tool. It can also exploit unpatched software, or arrive inside a trusted package.
Attackers favour the easiest route, not the cleverest.
What should we do if we find malware?
Isolate the affected machine, keep evidence, change credentials it may have seen, and look for spread. Do not simply delete the file and carry on.
Follow your incident playbook and see containment.
Related
Terms that sit next to this one
Ransomware
Malware that locks your data and demands payment to unlock it.
File upload vulnerability
An upload feature that accepts files it should refuse, such as scripts.
Supply chain attack
Reaching you through a library, a build tool or a vendor you trust.
EDR
Software on laptops and servers that records activity and spots attacks.
Malicious package
A published library built to steal data or run code on whoever installs it.
Can someone upload a file you serve on?
File upload features are a common route for harmful content. We test them in your web app and report what we actually got through, with the request and response. Ask us to run it on one of your applications.
Or start with a $199 pilot on one application: thirty days, success criteria agreed before day one, credited against the annual if you convert.