Avast researchers detect a September surge in malvertising

Avast Threat Labs 17 Nov 2023

Explore the rise of malvertising in September. Learn about the latest tactics in malicious online ads and how to protect yourself.

Bu Alexej Savčin, Gen Senior Malware Analyst

September is a month of change—summer holidays come to an end, school kicks off—and cybercriminals engage in increases illicit online activities." According to our data, the month of September commonly sees a sizable increase in the number of cyber threat detections reported across multiple vectors when compared to preceding summer months. Notably, within September we observed two particularly pronounced surges in the volume of malicious advertising incidents, also known as "malvertising.   


This September rise in detected cyber threats is likely a consequence of shifting behaviors as individuals resume regular work and school schedules following the more relaxed pace typical of the summer holiday period. Cybercriminals may take advantage of this transition, operating under the assumption that heightened online activity and connectivity provides additional opportunities to widely disseminate malware or steal personal information.  

 What is malvertising? 

Malvertising is a malicious online advertising technique that involves the distribution of malware through online ads or, in some cases, in conjunction with browser push notifications. Cybercriminals use these seemingly legitimate ads to deliver malware to unsuspecting users' devices when they click on or interact with the compromised advertisements.  

Cybercriminals are smart enough to make their malvertising pop-ups look genuine. Frequently, these fraudulent pop-ups exploit the recognizable antivirus company’s logo. The goal is to convince users they are encountering a legitimate notification from an antivirus provider. These alerts typically display messages that a virus on a computer has been found and that the subscription plan has expired.  

Upon clicking these deceptive pop-ups, unsuspecting users may find themselves redirected to a fake website. These fraudulent sites often take the form of straightforward phishing pages, where users are asked to enter personal credit card information under the guise of providing antivirus services. The scam can take many forms.  

We have warned about malicious push notifications in previous reports; this quarter is no exception. This method continues to remain popular with scammers as its effectiveness is still considerable, especially on mobile phones.  

What are current examples of malvertising? 

Malvertising comes in a few different types. Here are two of the main ones we’ve seen this quarter. 

Push notifications 

One of the most common examples of this malvertising was a page that fell into the push notification section that often appeared as part of a redirect chain. This page has multiple variations. The main purpose is to simply convince the user to allow push notifications.  


Push notifications can be especially effective on mobile devices, where they can also be disguised as system notifications, such as an unanswered call or a new text message.  

Social media ads 

Push notifications are not the only powerful tool for scammers. We have reported many times that scammers like to use advertising space on popular social networks. This way of promotion is especially dangerous because many users consider their social platforms to be a safe and personal space. Scammers also design their ads to attract attention, often by using catchy text or the faces of famous personalities. Thanks to this, the success rate of these campaigns is quite high.  

Another big advantage for scammers utilizing social media ads is their ability to precisely target and tailor content to vulnerable users. Consequently, users may find their social media feeds full of these types of ads over time.  In the example below, the malvertiser uses the Tesla and Elon Musk names to hook people.



These above ad examples are from Facebook. In this case, these ads are part of a single fraudulent financial scam where scammers are trying to trick users into investing in an Elon Musk/Tesla project. After clicking on the ad, the user is redirected to a web page where they are informed about the great benefits and the certainty that this project is profitable.  In neither case were the ads created by the subject names (Elon Musk or Tesla). 


As above, this example of malvertising uses a name brand (Tesla) to give the impression of professionalism. Part of the scam is also an appeal to the unrealistic possibility of buying through an 'automatic robot' that invests itself and 'automatically' earns money.  


These fake sites can take many forms. Often there are variations that mimic the world's famous media such as BBC News and many others. These ads take advantage of the targeting of ads that social platforms allow them to do; the ads click through to websites that are created for users in individual countries that correspond to popular news sites in those countries.  

The landing pages in this campaign also contain a registration form that requires users to enter their contact information. This information is then sent to the scammer, who then contacts the user either by email or, more often, by phone. Then the actual scamming effort is done over the phone.  


After filling out these fraudulent forms, the user can expect a phone call from the fraudsters. The caller subjects the prospective buyer to a thorough questioning, giving the impression that the financial company is checking not only the solvency of the prospective buyer but also their professional and financial knowledge level. The prospective client is then persuaded to install a remote computer access application, in this case, usually AnyDesk.  

 How to avoid falling for a malvertising scam 

To help avoid such scams, we strongly advise the following:  

  • do not disclose your personal information to people you do not know or cannot authenticate  
  • do not send photocopied personal documents  
  • do not send any printed credit card information  
  • do not give a code that would allow someone to access your computer remotely  
  • if someone is remotely connected to your computer for any reason, do not log into your online banking  
  • do not forward or tell anyone SMS bank authorization codes  
  • do not authorize a payment to a stranger  
  • keep an antivirus program installed on your computer  
  • keep your online banking limits as low as possible and increase them only to the actual need to pay a specific payment  

Real samples found on the web, not generated by us. Any logos or trademarks displayed are the registered trademarks of their respective brands.


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