Do not trust scam sites promoting Important Defender update available

Also Known As: Important Defender update available pop-up
Damage level: Medium

What is the "Important Defender update available" scam?

"Important Defender update available" is a fake message displayed by untrustworthy websites. This scam claims that users need to update their Windows Defender anti-virus software. It must be emphasized that this scheme is in no way associated with the Microsoft Corporation - Windows product developers.

The "Important Defender update available" scam has been observed promoting dubious/malicious applications through the legitimate Microsoft installation setup. However, it is not unlikely that this scheme may proliferate different content via other installers.

Scams of this type are typically used to endorse fake anti-virus tools, adware, browser hijackers, and other PUAs (Potentially Unwanted Applications). These schemes may also proliferate malware, e.g., trojans, ransomware, cryptocurrency miners, etc. Most users access deceptive sites unintentionally.

They enter the pages through mistyped URLs, redirects caused by intrusive ads, or have them force-opened by installed PUAs.

Important Defender update available scam

The scam closely mimics the visual graphics of Microsoft Windows content, thereby increasing the impression of the site's legitimacy. The text presented in this scheme urges users to download/install the endorsed software by claiming that it's an important Windows Defender update.

At the time of research, the scam uses the genuine Microsoft installer to spread its untrustworthy and/or dangerous content.

By trusting the "Important Defender update available" scheme and downloading/installing the fake updates, users can experience system infections, severe privacy issues, financial losses, and even identity theft.

PUAs are commonly distributed through online scams. These applications appear legitimate and offer "handy" functionalities, which are rarely operational. Fake anti-viruses are prime examples of this type of PUAs.

They require activation (i.e., purchase) to perform the advertised features, yet following activation - the functions remain nonoperational.

Furthermore, unwanted apps can have unmentioned, heinous abilities. Some PUAs can force-open misleading, deceptive, and malicious websites (e.g., ones running "Important Defender update available"). Adware-types run intrusive advertisement campaigns.

Once clicked on, the delivered ads redirect to harmful webpages and may be able to stealthily download/install software. Browser hijackers are another type of PUAs. They operate by making changes to browser settings and restricting/denying access to them - in order to promote (by causing redirects to) fake search engines.

The promoted web searchers seldom can provide search results, so they redirect to Google, Bing, Yahoo, and other legitimate search engines. What is more, most PUAs can track data. Information of interest includes: browsing activity, IP addresses, geolocations, personally identifiable details, and so on.

The collected data is then shared with and/or sold to third-parties. Therefore, it is strongly advised to remove all suspicious applications and browser extensions/plug-ins without delay. Scams likes "Important Defender update available" have been noted proliferating malware as well.

This dangerous software can have various malicious functionalities, and these functions can be in different combinations. Trojan is a broad malware type, which can be designed to steal data, spy on users, cause chain infections, and so on.

To elaborate, these malicious programs may enable remote access and control over the infected device (Remote Access Trojans - RATs), exfiltrate content stored on the systems, extract information from installed browsers and other applications, record key-strokes (keylogging) or audio/video, download/install additional malware, etc.

Ransomware operates by encrypting files and/or locking the device's screen - to demand ransoms for the decryption/ access recovery. Cryptominers use system resources (potentially, to the point of permanent hardware damage) to generate cryptocurrency.

Therefore, to ensure device integrity and user safety, it is crucial to immediately use anti-virus tools to remove all malware infections.

Threat Summary:
Name Important Defender update available pop-up
Threat Type Phishing, Scam, Social Engineering, Fraud
Fake Claim Scam implies that users must update their Windows Defender.
Distributed Unwanted Apps Various dubious and/or malicious applications
Detection Names (installer) AegisLab (Trojan.MSIL.Reline.i!c), ESET-NOD32 (A Variant Of MSIL/Spy.Agent.BXY), Kaspersky (HEUR:Trojan-PSW.MSIL.Reline.gen), Malwarebytes (Malware.AI.4022418607), McAfee (Artemis!1AE6FB4E1B4B), Full List Of Detections (VirusTotal)
Related Domains updatedefender[.]online
Serving IP Address (updatedefender[.]online)
Symptoms Fake error messages, fake system warnings, pop-up errors, hoax computer scan.
Distribution methods Compromised websites, rogue online pop-up ads, potentially unwanted applications.
Damage Loss of sensitive private information, monetary loss, identity theft, possible malware infections.
Malware Removal (Windows)

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The Internet is full of misleading, deceptive, and malicious material. Online scams aim to gain and subsequently abuse users' trust - to generate profit at their expense. Various tactics and techniques are employed to achieve this goal.

Popular scam models include: alerts that a piece of essential software is outdated or missing (e.g., vpn1aprotectplus[.]com, "Fake flash player update", etc.), warnings that the system is infected or at risk ("Firewall Spyware Alert", "Your System Detected Some Unusual Activity", etc.), fake prize raffles (e.g., "Google Membership Rewards", "Chrome search contest 2021", etc.), ludicrous deals and offers (e.g., "Binance giveaway", "Doge Giveaway", etc.), and so on.

Regardless of what these scams claim, offer, request, or demand - trusting them can result in a variety of severe problems. Due to how widespread online schemes are, it is highly recommended to exercise caution when browsing.

How did potentially unwanted applications install on my computer?

PUAs are distributed through download/installation setups of other programs. This deceptive marketing technique of packing regular software with unwanted or malicious additions - is called "bundling".

Rushed download/installation processes (e.g., skipped steps and sections, etc.) increase the risk of inadvertently allowing bundled content into the system. Intrusive adverts are also used to spread PUAs. Once clicked on, the ads can execute scripts to make downloads/installations without user consent.

PUAs can have "official" download webpages, which are often promoted by scam sites.

How to avoid installation of potentially unwanted applications?

It is important to research software prior to download/installation and/or purchase. Additionally, only official and verified download channels must be used.

Untrustworthy sources, e.g., unofficial and free file-hosting websites, Peer-to-Peer sharing networks, and other third-party downloaders - commonly offer harmful and bundled content.

When downloading/installing, it is recommended to read terms, study all available options, use the "Custom/Advanced" settings, and opt-out from additional apps, tools, features, etc.

Intrusive advertisements appear legitimate and innocuous; however, they redirect to unreliable and questionable webpages (e.g., gambling, pornography, adult-dating, and many others).

In case of encounters with ads and/or redirects of this kind, the system must be inspected and all suspicious applications and browser extensions/plug-ins detected - immediately upon detection.

If your computer is already infected with PUAs, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate them.

Text presented in the "Important Defender update available" scam:

Update Windows Defender

Important Defender update available. Click "Install" to continue.

Program    windef.exe
Verified Publisher: Microsoft Corporation
Necessary measures: Click "Install", then "Allow" and then "Add" to continue.

Install Cancel
Do not show this notification again

Screenshot of the installation setup promoted via "Important Defender update available" scam:

Important Defender update available scam promoted installer

The appearance of "Important Defender update available" pop-up scam (GIF):

Appearance of Important Defender update available scam (GIF)

Instant automatic malware removal: Manual threat removal might be a lengthy and complicated process that requires advanced IT skills. Combo Cleaner is a professional automatic malware removal tool that is recommended to get rid of malware. Download it by clicking the button below:
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Quick menu:

How to identify a pop-up scam?

Pop-up windows with various fake messages are a common type of lures cybercriminals use. They collect sensitive personal data, trick Internet users into calling fake tech support numbers, subscribe to useless online services, invest in shady cryptocurrency schemes, etc.

While in the majority of cases these pop-ups don't infect users' devices with malware, they can cause direct monetary loss or could result in identity theft.

Cybercriminals strive to create their rogue pop-up windows to look trustworthy, however, scams typically have the following characteristics:

  • Spelling mistakes and non-professional images - Closely inspect the information displayed in a pop-up. Spelling mistakes and unprofessional images could be a sign of a scam.
  • Sense of urgency - Countdown timer with a couple of minutes on it, asking you to enter your personal information or subscribe to some online service.
  • Statements that you won something - If you haven't participated in a lottery, online competition, etc., and you see a pop-up window stating that you won.
  • Computer or mobile device scan - A pop-up window that scans your device and informs of detected issues - is undoubtedly a scam; webpages cannot perform such actions.
  • Exclusivity - Pop-up windows stating that only you are given secret access to a financial scheme that can quickly make you rich.

Example of a pop-up scam:

Example of a pop-up scam

How do pop-up scams work?

Cybercriminals and deceptive marketers usually use various advertising networks, search engine poisoning techniques, and shady websites to generate traffic to their pop-ups. Users land on their online lures after clicking on fake download buttons, using a torrent website, or simply clicking on an Internet search engine result.

Based on users' location and device information, they are presented with a scam pop-up. Lures presented in such pop-ups range from get-rich-quick schemes to fake virus scans.

How to remove fake pop-ups?

In most cases, pop-up scams do not infect users' devices with malware. If you encountered a scam pop-up, simply closing it should be enough. In some cases scam, pop-ups may be hard to close; in such cases - close your Internet browser and restart it.

In extremely rare cases, you might need to reset your Internet browser. For this, use our instructions explaining how to reset Internet browser settings.

How to prevent fake pop-ups?

To prevent seeing pop-up scams, you should visit only reputable websites. Torrent, Crack, free online movie streaming, YouTube video download, and other websites of similar reputation commonly redirect Internet users to pop-up scams.

To minimize the risk of encountering pop-up scams, you should keep your Internet browsers up-to-date and use reputable anti-malware application. For this purpose, we recommend Combo Cleaner Antivirus for Windows.

What to do if you fell for a pop-up scam?

This depends on the type of scam that you fell for. Most commonly, pop-up scams try to trick users into sending money, giving away personal information, or giving access to one's device.

  • If you sent money to scammers: You should contact your financial institution and explain that you were scammed. If informed promptly, there's a chance to get your money back.
  • If you gave away your personal information: You should change your passwords and enable two-factor authentication in all online services that you use. Visit Federal Trade Commission to report identity theft and get personalized recovery steps.
  • If you let scammers connect to your device: You should scan your computer with reputable anti-malware (we recommend Combo Cleaner Antivirus for Windows) - cyber criminals could have planted trojans, keyloggers, and other malware, don't use your computer until removing possible threats.
  • Help other Internet users: report Internet scams to Federal Trade Commission.

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About the author:

Tomas Meskauskas

Tomas Meskauskas - expert security researcher, professional malware analyst.

I am passionate about computer security and technology. I have an experience of over 10 years working in various companies related to computer technical issue solving and Internet security. I have been working as an author and editor for pcrisk.com since 2010. Follow me on Twitter and LinkedIn to stay informed about the latest online security threats. Contact Tomas Meskauskas.

PCrisk security portal is brought by a company RCS LT. Joined forces of security researchers help educate computer users about the latest online security threats. More information about the company RCS LT.

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Malware activity

Global malware activity level today:

Medium threat activity

Increased attack rate of infections detected within the last 24 hours.

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