Q.List some common signs of malware infection.

This is a plain theory question — it asks you to list, not to pick an option or run code. So the answer should be crisp bullet points, each with a one-line explanation of why that sign points to malware.

Common signs of malware infection:

• System slows down drastically — malware runs background processes (mining, spamming, keylogging) that eat CPU and RAM.
• Frequent pop-ups and unwanted ads — adware injects ads into the browser even on sites that normally show none.
• Unexpected programs start at boot — the virus adds itself to startup entries so it survives reboots.
• Files get corrupted, renamed, or encrypted — ransomware encrypts files and demands payment; other malware deletes or alters data.
• Browser homepage/search engine changes without your consent — browser hijackers modify settings to redirect traffic.
• Antivirus software is disabled or won't update — many viruses specifically kill security tools to avoid detection.
• Unusual network activity — the infected machine sends data out (data theft) or receives commands from a remote server.
• New unknown processes in Task Manager — a process you never installed is running, often with a random name.
• System crashes or Blue Screen of Death (BSOD) — malware corrupts system files or drivers, causing instability. …

This is a plain theory question, so I'll give you the explanatory treatment: the why behind each sign, not just a checklist. Think of malware as an uninvited guest in your house — it eats your food (CPU/RAM), rearranges your furniture (files), and shouts out the window (pop-ups). Every symptom below is that guest leaving evidence.

The Core Idea: Malware Needs Resources and Leaves Traces

Malware is software, and software needs three things to run: processing power, memory, and network access. It also wants to hide, so it often disables your defenses. When you see a cluster of these signs, you're seeing the malware's "footprints" — its resource usage, its side effects, and its attempts to survive.

The Common Signs, Grouped by What They Reveal

1. System Slowdown and High Resource Usage

The most universal sign. A virus that mines cryptocurrency, sends spam emails, or runs a botnet will peg your CPU at 100%. Your fan spins up, programs take forever to open, and even simple tasks lag. Check Task Manager (Windows) or Activity Monitor (macOS) — if an unknown process is eating 90% CPU, that's your culprit.

2. Pop-ups, Ads, and Browser Hijacking

Adware and browser hijackers are the loudest malware. You'll see:

• Pop-up ads even when no browser tab is open.
• Your homepage or search engine changed without your permission.
• New toolbars or extensions you never installed.
• Websites redirecting you to fake "virus detected" pages that try to scare you into buying software.

This happens because the malware injects code into your browser's settings or uses a proxy to rewrite web traffic.

3. Files and Programs Behaving Strangely

Ransomware and file-infecting viruses are the destructive kind. Watch for:

• Files that won't open, or open with garbled content (encryption in progress).
• Files renamed with odd extensions like .encrypted or .locked.
• Entire folders disappearing or being moved.
• Programs crashing randomly or failing to start — the virus may have overwritten their executable files.

4. Unusual Network Activity

Spyware and trojans phone home. Signs include:

• Your internet is slow even when you're not downloading.
• Your data usage spikes for no reason (check your router's stats or data meter).
• Programs you didn't run are connecting to the internet — check your firewall logs or use netstat to see active connections.

5. Security Software Disabled or Missing

Smart malware attacks your defenses first. If your antivirus is turned off, won't update, or won't reinstall, that's a red flag. Some malware also blocks access to security websites so you can't download help.

6. System Instability and Crashes

Blue screens, random restarts, and freezes. Malware that hooks deep into the operating system (rootkits, bootkits) can destabilize it. Frequent crashes that started recently, with no hardware change, are suspicious. …