Questions tagged [antivirus]

Antivirus or anti-virus software is used to prevent, detect, and remove malware, including but not limited to computer viruses, computer worm, trojan horses, spyware and adware.

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170
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10answers
27k 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. ...
161
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10answers
20k views

How do you explain the necessity of “nuke it from orbit” to management and users?

When a machine has been infected with malware, most of us here immediately identify the appropriate action as "nuke it from orbit" - i.e. wipe the system and start over. Unfortunately, this is often ...
161
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14answers
17k 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 ...
147
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19answers
40k 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 ...
124
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8answers
19k views

Are there technical differences which make Linux less vulnerable to virus than Windows?

What makes Linux so different than Windows in terms of anti-virus needs? My question is not if I should get an anti-virus for my Linux. I perfectly understand why an AV is important. I would like ...
112
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9answers
19k 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 ...
102
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3answers
25k views

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 ...
91
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7answers
51k 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 desktop ...
82
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2answers
17k views

I'm a White Hat and I develop my own viruses. Should I report it when almost all scanners say the executable is safe?

I develop my own viruses for 'scientific' purposes, namely to see if they pass the test of Virustotal.com. They all do, except for one or two scanners. Is this considered something you should report ...
80
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7answers
16k views

Company claims hardwire connections are a security issue

Someone to whom I am related is at a study camp for their desired profession. This person, let's call her Jane, is supposed to be studying rigorously for two months. The housing provided offers ...
77
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15answers
17k views

How to write an email regarding IT Security that will be read, and not ignored by the end user?

I've observed that several of our users are ignoring messages sent from IT Security managers, and also the system generated "You just sent a virus" notifications. The problem seems to be among people ...
53
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8answers
15k 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 ...
52
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10answers
17k views

Replacing Windows 7 security updates with anti-virus?

Microsoft has announced Windows 7 will no longer be receiving updates after January 14, 2020: Here. I hate windows 10's forced updates and telemetry so I have always stuck with Windows 7, but it may ...
47
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2answers
19k views

How do antiviruses scan for thousands of malware signatures in a short time?

Most antiviruses have hundreds of thousands or even millions of malware signatures and yet they scan many files in a reasonable short time with high detection rates. Even real-time scanners doesn't ...
44
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8answers
24k views

Are two anti-virus better than one in protecting your computer?

A century old adage: The more the merrier. In general, does this adage hold true in regards to the number of anti-virus software you should have on your PC? Are there any limits before it actually ...
42
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2answers
14k views

How secure is the Windows 8 included Anti Virus known as Windows Defender?

How secure is the new Windows 8 anti virus known as Windows Defender? Does it have a protection against malware which uses UAC bypass/process injection/rootkits/process persistence/running the binary ...
41
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5answers
11k views

Accidentally came across the source code for some malware, what to do?

I accidentally, the other day, went to a dodgy site, and today I discovered that in my cache there lay a text file. And after reading the contents of the file, I have deduced that it is the source ...
40
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4answers
6k views

Are there any known cases of antivirus software intentionally sending false alarms?

First things first, I'm not asking this question because of any specific alarm on my PC that I suspect to be false. It's just that from the perspective of the software industry, it would make some ...
40
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3answers
8k views

Can anti-virus/virus protection be used to spy on you? [closed]

I'm a complete noob when it comes to these subjects. But here goes... Let's say someone is using a VPN, TOR, or some other tool to enhance their privacy. As I understand it, you are discouraged from ...
39
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4answers
8k views

Avast AV could read Firefox saved passwords

My friend uses Firefox's built-in password manager feature to save passwords for sites. Later, after installing Avast Free Antivirus there was a feature called Passwords on the Avast UI. When accessed ...
39
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5answers
53k views

How to scan a PDF for malware? [closed]

Can anyone suggest an automated tool to scan a PDF file to determine whether it might contain malware or other "bad stuff"? Or, alternatively, assigns a risk level to the PDF? I would prefer a free ...
38
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6answers
11k views

Can malware be dangerous even when quarantined?

I am reading a book on network security and when talking about user confusion it writes: "It is not uncommon for a user to be asked security questions such as Is it safe to quarantine this ...
38
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5answers
46k views

Is HTML5 vibrate feature a security vulnerability?

While surfing a news website on my mobile, I receive a virus infection alert warning that triggers my phone to vibrate incessantly. The alert looks like the following: I didn't expect my phone to ...
36
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3answers
43k views

Why is 'avast! Web/Mail Shield Root' listed as CA for google.com?

I just noticed something weird in my browser: the certificate for www.google.com has been issued by avast! Web/Mail Shield Root. Should I be worried? I am using avast! Antivirus so it's probably a ...
33
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4answers
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 ...
28
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10answers
8k views

How to explain to a customer that spamfilters don't catch everything

I used to work in a small office which provided basic desktop support for users. One day I had to answer a call from a very angry customer and he asked for my boss. He wanted to know how could one ...
27
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8answers
7k views

What makes it difficult to have a hardware antivirus?

Posting systems are vulnerable to virus and worms and having an antivirus is almost necessary. How is it possible that hardware antiviruses don't exist? The idea sounds pretty good, if the antivirus ...
26
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3answers
15k views

Metasploit Meterpreter alternatives

These days I am testing various type of client hacking techniques, but in all scenarios I am using Meterpreter variations as payload. Now I can bypass Anti-Virus and Firewalls easily, but Symantec ...
26
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3answers
4k views

Could malware move during a scan to avoid detection?

I think every AV-Scanner is using some predictable recursive scan to search files for malware. Couldn't malware easily detect a scan and just move to an already checked location, determined by knowing ...
23
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2answers
3k 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 ...
23
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3answers
7k 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?
23
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2answers
8k views

How do anti-virus apps for Android work?

There seems to be a lot of anti-virus apps for Android. On a desktop or server an anti-virus must run with super-user privileges, however I am pretty sure these mobile anti-viruses are running as an ...
22
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5answers
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 ...
22
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4answers
19k views

Does a webserver need an antivirus software installed?

In what cases does a webserver need an antivirus software installed? When it is not required? If it is required sometimes, what should be considered when choosing the right one to install? (In my ...
22
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3answers
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 ...
21
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8answers
3k views

Are signature based antivirus or antimalware effective?

Are signature based antivirus or antimalware solutions effective? Has the battle been lost against the ever increasing amount of malware, particularly rootkits, that are in the wild?
20
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7answers
1k 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 ...
20
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6answers
4k 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 ...
20
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1answer
2k views

EICAR Virus Test maliciously used to delete logs?

Today at work I was asked to test our anti-virus software on our Linux servers. I attempted to create a text file containing the EICAR Virus Test signature. The file was deleted instantly, ...
17
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4answers
13k views

Do Linux systems need antivirus against ransomware? [closed]

I use Linux to store private data and backups for my team because it is said that Linux is itself very secure from malware and doesn't need antivirus. But now as ransomware is spreading and has ...
17
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4answers
2k views

How AV software makes sure quarantined files never get executed? [duplicate]

This Super User question made me ask, is it really a good idea to keep files in quarantine, when you don't know what they are yet? For what I know there are more or less 2 steps that need to be ...
16
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2answers
12k views

How to pass PCI DSS 2.0 anti-virus requirement (5.1) on Linux?

PCI DSS 2.0 Requirement 5.1 states: 5.1 Deploy anti-virus software on all systems commonly affected by malicious software (particularly personal computers and servers). This requirement (although ...
15
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4answers
9k views

Can I block viruses from a USB stick by scanning it before opening its folder?

I inserted my USB stick into a friend's PC which was full of viruses, malwares and adwares. Therefore I suppose they attacked my USB device as well. Now I want to use my USB device on my PC without ...
15
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6answers
12k views

How can I safely back-up files from an infected computer?

Imagine a laptop that's been infected by malware, and that the owner hasn't backed-up their files.* They have pictures, videos, and documents they'd like to preserve, so they're hesitant to ...
15
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3answers
7k views

Where Does ClamAV Get Its Virus Signatures?

I see that ClamAV has virus definition files which are mostly hash codes in md5, sha1, and sha256 formats, which either look at the whole file or what are called PE sections of an executable file. Of ...
14
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8answers
3k views

Are antiviruses still useful? [duplicate]

Are anti-viruses useful nowadays ? Given the number of viruses that are developed and spread monthly, and given the fact anti-viruses are based on virus signatures, I wonder how much it is useful and ...
14
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4answers
2k views

How effective are anti-virus products against real-world threats?

In a recent interview† with Dave Kennedy, he in passing pegged the average effectiveness of anti-virus products as detecting approximately 3% to 5% of current active threats. While AV comparisons ...
13
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3answers
44k views

How serious is InstallIQ?

Background: Recently I've seen hits for InstallIQ a "potentially unwanted application" from ESET. From what I can find it seems like this is an installer wrapper that asks people to install other ...
13
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2answers
6k views

Custom Metasploit payload with UAC bypass

The machine I am attacking has anti-virus installed. I have managed to use Veil Framework in order to create an initial reverse shell payload that is undetected by the AV. However, UAC is enabled on ...
12
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2answers
2k views

Are there / have there ever been viruses that completely evade virus scanners for very long?

Are there, or have there ever been viruses that completely evade all virus scanners for a long time (e.g. longer than a year?)