Questions tagged [virus]

A computer virus is a program or piece of code that tends to be malicious and is loaded onto your computer without your knowledge and runs against your wishes.

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What should you do if you catch encryption ransomware mid-operation?

You boot up your computer one day and while using it you notice that your drive is unusually busy. You check the System Monitor and notice that an unknown process is using the CPU and both reading and ...
Fiksdal's user avatar
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182 votes
11 answers
37k views

Help! My home PC has been infected by a virus! What do I do now?

This is an attempt to ask a canonical question as discussed in this old meta post. The goal is to create something helpful that can be used as a duplicate when non experts ask about virus infections. ...
Anders's user avatar
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163 votes
5 answers
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How can USB sticks be dangerous?

We all know the story of the USB drive left outside a power plant which was found by a worker and inserted into a computer to see the contents which then allowed a hack to ensue. Here is my question, ...
TheHidden's user avatar
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160 votes
14 answers
19k views

What is the safest way to deal with loads of incoming PDF files, some of which could potentially be malicious?

As an investigative journalist I receive each day dozens of messages, many of which contain PDF documents. But I'm worried about some of the potentially malicious consequences of blindly opening them ...
Tom the journalist's user avatar
153 votes
19 answers
43k views

Has it been mathematically proven that antivirus can't detect all viruses?

What analysis was Bruce Schneier referencing when he wrote: Viruses have no “cure.” It’s been mathematically proven that it is always possible to write a virus that any existing antivirus program ...
Cate's user avatar
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136 votes
10 answers
41k views

Can a computer virus be stored somewhere else than on the hard drive?

Are there viruses that have managed to hide themselves somewhere other than on the hard drive? Like CPU cache or on the motherboard? Is it even possible? Say I get a virus, so I get rid of the HDD ...
Ivan Bilan's user avatar
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118 votes
10 answers
21k views

Alternatives to anti-virus for keeping oneself safe

I have read a lot of articles that talk about how using an AV is less safe than not having one for more intermediate PC users who are careful with what they click and download. For example, here are ...
delacroix's user avatar
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104 votes
3 answers
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How are anti viruses so fast?

The common anti-virus (to my knowledge) uses a kind of brute force type method where they get the hash of the file and compare it to thousands of known virus' hash. Is it just they have servers with ...
Harry's user avatar
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104 votes
2 answers
33k views

Can a rogue .wmv file "hijack" Windows Media Player?

I've downloaded a .wmv file using P2P. Attempting to play it with Media Player Classic (K-Lite Codec Pack) only gave me a green square in the playback window: I noticed that the video came with a ...
user4520's user avatar
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99 votes
9 answers
38k views

Can a virus destroy the BIOS of a modern computer?

In the late 1990s, a computer virus known as CIH began infecting some computers. Its payload, when triggered, overwrote system information and destroyed the computer's BIOS, essentially bricking ...
user73910's user avatar
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91 votes
7 answers
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Should I get an antivirus for Ubuntu?

Considering the recent thread regarding anti-virus for the Mac I wonder how many of the arguments put forth are relevant today to Linux systems, specifically Ubuntu. There are no known Ubuntu desktop ...
dotancohen's user avatar
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86 votes
4 answers
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What is the risk of copy and pasting Linux commands from a website? How can some commands be invisible? [duplicate]

Like all beginners in the land of Linux, I usually look for websites that contain some useful shell commands, mark it with my mouse, copy it (CTRL + C) and paste it into a terminal. For example, if ...
GAD3R's user avatar
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70 votes
5 answers
69k views

Can my mouse have virus and infect other machines?

This is my mouse. I used it with my old computer which was full of viruses. If I use this mouse for my new PC, can my new computer be infected from my mouse?
Nhật Phát's user avatar
67 votes
4 answers
15k views

Why is so much ransomware breakable?

The site: https://www.nomoreransom.org/ offers many decrypter tools for ransomware. But why? It shouldn't be so hard to use the Windows Crypto API (e.g. just google "create AES Key in Windows") to ...
kiara's user avatar
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59 votes
9 answers
43k views

Can malware be attached to an image?

I have a small number of employees who use a company computer but these people aren't very tech-savvy. They use an email client and a messaging client. I'm pretty sure they wouldn't click on a .exe or ...
user2143356's user avatar
56 votes
8 answers
16k views

Should I get an antivirus for my Mac?

There are some people saying that people should use an antivirus software on Mac. And there are thousands of people claiming that Macs don't get viruses (under this term I mean spyware / malware as ...
gen's user avatar
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55 votes
11 answers
47k views

Can headphones transmit malware?

Can headphones transmit malware? My friend borrowed my headphones (a pair of Apple EarPods) and plugged them into his Android mobile phone for a few minutes in order to listen to a voice message. ...
tonychow0929's user avatar
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55 votes
8 answers
18k views

Virus Encoded in Video

So I'm not familiar at all with IT Security, but I'm a bit curious about something. I was watching a TV show and at one point, a virus spreads through an office. They investigate and find out that the ...
pasawaya's user avatar
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53 votes
5 answers
52k views

Can malicious code trigger without the user executing or opening the file?

If a file is downloaded from the Internet, and saved on disk, but is not opened by a user (if we keep autorun off), are there any chances that malicious code (e.g. a virus) in the file could trigger? ...
ahinath's user avatar
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52 votes
4 answers
147k views

How to inject executable, malicious code into PDF, JPEG, MP3, etc.?

I wanted to know if its generally possible to inject executable code into files like PDFs or JPEGs etc., or must there be some kind of security hole in the application? And if so, how would one do ...
JohnnyFromBF's user avatar
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47 votes
3 answers
7k views

Help! Ransomware encrypted my files. What do I do now?

I just discovered that my files have been encrypted by ransomware. Can I get my files back? How? Should I pay the ransom? What should I do so that this never happens again?
Anders's user avatar
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46 votes
2 answers
23k views

What malicious things can happen when clicking on links in email?

I've received a spam from one of my friends (well I'm sure he didn't send it). so there's this link, and i'd thought what exactly would be the implications of clicking the link (i've not clicked it ...
Pacerier's user avatar
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45 votes
7 answers
14k views

Does a virus need to be clicked on to function?

Can a virus infect my Windows XP operating system by its mere presence? I mean, if I copy/paste a virus on my computer and I never click on it, will it infect my computer or will it remain dormant, ...
user avatar
44 votes
9 answers
494k views

How can I watch porn, safely, and not get a virus on my machine or infect corporate data

I'm part of a small office in the middle of nowhere, and we just got absorbed into a large mega corporation. Sometimes we watch porn, at the office, on company computers, using the company Internet. ...
TLDR's user avatar
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42 votes
7 answers
27k views

Can cookies carry viruses?

I was wondering whether a cookie can carry a virus (or any security-threatening code). In some sense it is similar to a download. So by simply visiting a site, could I get harmed?
Mero55's user avatar
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35 votes
1 answer
25k views

Was Goggle.com actually crazy malware in 2006?

This video shows how somebody accidentally opens Goggle.com instead of Google.com. He gets flooded with pop-ups, SpySheriff or SpywareSTOP get installed automatically, and the computer user has no ...
neverMind9's user avatar
34 votes
1 answer
5k views

Has malware ever been found in a package from a large Linux distribution and what is done to prevent this from occurring?

I am wondering exactly how safe are the Arch, Ubuntu, Mint and Manjaro repositories. What testing is done to ensure that a trusted user does not place a virus in a package, and how often?
user's user avatar
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33 votes
11 answers
16k views

Is it dangerous to pass documents from an old infected laptop to a new one?

My old laptop is possibly infected. But I just want to transfer documents that I have created like Excel or Word files. Is it possible that malware entered into these files making it dangerous to ...
Jan Charles Butter's user avatar
33 votes
4 answers
4k views

Are anti-virus companies companies regularly committing software piracy?

As Mikko Hypponen highlighted in a recent tweet, anti-Virus companies collect and store both samples of malicious software and samples of legitimate software: This got me to thinking, what ...
Andy Smith's user avatar
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31 votes
3 answers
11k views

Do I really need an Anti-Virus software if I'm careful about where I browse?

A friend told to me the following: I don't use Anti-Virus software at all, I am just careful about where I go and what I click on. I've also heard this from other people as I've repaired their PC'...
James Mertz's user avatar
30 votes
5 answers
31k views

Find Virus in an Image File

I just received a .jpg file that I'm almost positive contains a virus, so I have two questions about what I am able to do with the image. My first question originates from the fact that I opened the ...
kmecpp's user avatar
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30 votes
5 answers
14k views

Almost fell for "tech support" scam - what is the risk?

An acquaintance of mine got a call from an alleged Microsoft employee and provided him access to his Windows 10 computer via team viewer (commonly known as the tech support scam). But when the scammer ...
Phil's user avatar
  • 411
28 votes
2 answers
2k views

Is there a real possibility of getting malware by “drive-by”?

I know malware can be gotten by downloading and running stuff, but is there a real possibility of just viewing a webpage or clicking a link and getting one? Assuming using only Firefox / Chrome and ...
Startup1's user avatar
  • 383
28 votes
6 answers
4k views

Why do malware creators use such clever technologies for such silly purposes?

Some days ago I got infected by a malware, probably something new and very clever, as it went in unstopped and no scanning tool was able to detect it afterwards (see this question). It was a two-...
Massimo's user avatar
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27 votes
4 answers
11k views

Are popular porn sites more likely to be infected with malware?

I'm trying to help my friend understand this because he believes that since a site is very popular, that it's less likely to infect its viewers because of its security! Is a popular site less likely ...
Kervin Jacquet's user avatar
26 votes
2 answers
3k views

Could once infected machine be ever trusted again?

I'm just about to switch to a new SSD drive, so I figured it's a good occasion for a really, really fresh start. I reconsidered every installed piece of software, uninstalled lots of crap (...
vandalizmo's user avatar
26 votes
7 answers
32k views

Is malware distributed with pirated software actually common?

An often-repeated piece of conventional wisdom goes like the following. Don't download pirated software, they often contain malware. I'm curious to know if there are any hard facts to backup this ...
Alexander O'Mara's user avatar
25 votes
4 answers
10k views

What is the corrupted image vulnerability? How does it work?

What exactly happens when someone injects malicious binary code into an image file (on Windows)? How is that done?
Moshe's user avatar
  • 1,851
24 votes
2 answers
4k views

Cohen's problem

Fred Cohen determined theoritically that viral detetction is an undecidable problem. Can anyone provide an intuitive reasoning for that? Background Fred Cohen experimented with computer viruses ...
viv's user avatar
  • 667
24 votes
3 answers
3k views

Are older viruses removed from virus definition files?

Antivirus software receives constant updates in the form of virus definition files, containing the patterns used to identify viruses. It is a feature present on most (if not all) major AV for at least ...
That Brazilian Guy's user avatar
24 votes
3 answers
8k views

How does a crypter for bypassing antivirus detection work?

I am talking about crypters used to encrypt files like viruses and keyloggers for the sole purpose of bypassing antivirus detection. How do they work?
gbr's user avatar
  • 2,020
23 votes
3 answers
11k views

Is it possible to transfer a virus through browser video?

I know that there is already a question related to viruses in videos, but the implication in the other question is that videos in question have been downloaded and played by media software on the ...
Stumbler's user avatar
  • 513
22 votes
5 answers
2k views

Why would a virus writer bother to check to see if a machine is infected before infecting it?

I was looking at the tripartite structure of a virus, and it seems to check to see if a computer is infected before infecting it with the virus. Would this be an attempt to use files that are already ...
SwaroopGiwali's user avatar
22 votes
4 answers
6k views

Suspicious JavaScript in website header

I am not sure if this is the correct place to ask a questions such as this, apologies if it isn't. I have found the below code in the header of one of my wordPress websites, I am pretty sure it is ...
bf2mad's user avatar
  • 401
22 votes
6 answers
6k views

Malicious Links that Respond to Browsers but not curl or wget

There are some emails with links to people's cracked websites with a malware download Like this kind of email: fake DHL pack station email ... the links often take the form of: http:// www....
user145837's user avatar
22 votes
4 answers
14k views

Is it safe to serve any user uploaded file under only white-listed MIME content types?

Let's say I develop an application that, Allows any user to upload a file of only white listed mime content type and extensions (word and pdf). Serves those files with the allowed extension and ...
Andy's user avatar
  • 535
21 votes
5 answers
6k views

Is it possible for a file that is non-executable and read-only to run malicious code?

On a POSIX system, is there a possibility for a file which is non-executable and read-only (aka with a mode 444) to run malicious code on a machine? If so, can you explain how it would do so?
Idr's user avatar
  • 321
21 votes
4 answers
8k views

Is VLC on Linux vulnerable to an attack from .wmv files designed to install viruses? [duplicate]

I was stupid and did not check a video file I downloaded from an untrustworthy source. It was .wmv file with no readable properties of the video. I know that .wmv videos can download viruses. What I ...
user's user avatar
  • 829
21 votes
2 answers
5k views

Do the most common ransomware programs delete the original files as they go, or in a big bulk delete at the very end?

I'm talking about the most common varieties like Cryptolocker, Cryptowall, Torrentlocker, KeRanger, RSA4096, etc. (There is not necessarily a need to answer for all of these, one or two may do.) If ...
Fiksdal's user avatar
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