Js/Adrozek.A, BrowserModifier:JS/Adrozek.A, Trojan:Win32/Adrozek!rfn: what it is and how to remove it

From our report of Jan 2021 · not reviewed since

Js/Adrozek.A is based on "expansive, dynamic attacker infrastructure"

Browser hijackers are among the oldest threats on the internet and while they became much less of a headache for users over the years due to the implemented regulations and security measures, threats like Adrozek remain very harmful for everyone who are affected.

Since May 2020, security researchers from Microsoft have been observing the newest campaign that mainly targeted European and Indian internet users. The peak of infections was reached in August of the same year, when the tech giant saw more than 30,000 attempts to infect users on a daily basis.

Security experts wrote:

While the main goal of the attackers is to make users click on ads inserted at the top of the search results, there are far more dangerous traits of Js/Adrozek.A. Primarily, it was uncovered that, if installed, the virus can be very persistent and difficult to eliminate (due to its polymorphic aspect), and it can also compromise the host machine's security even further by stealing credentials entered on various websites.

Another disturbing feature of this campaign is that the attackers heavily rely on polymorphism during its distribution, which is performed via the drive-by download technique. Due to the ever-changing payload, many security solutions might fail to detect Adrozek, hence the infiltration rate is quite high.

Once installed, the malware drops several malicious files (Audiolava.exe, QuickAudio.exe, and converter.exe) into the Program Files folder. It then modifies the Windows registry to establish persistence and prevent all the affected browsers from being updated. It also creates a new service titled "Main Service" to prevent modification of the newly-established settings.

To mitigate Js/Adrozek.A and prevent its infiltration, ensure that your security software is running with the latest updates applied and also secure your operating system, as well as the installed software from vulnerabilities by patching them with the latest security updates.

From our report of Jan 2021 · not reviewed since

Do not ignore anti-malware software warnings

Security software is one of the essential components of any modern computer - industry experts advise keeping a robust anti-malware running at all times.

Unfortunately, there are plenty of people who ignore this advice and believe that they are smarter than malware - this couldn't be further from the truth, as modern computer threats are programmed in a way to operate without any trace whatsoever.

Additionally, many users visit high-risk torrent sites and download pirated programs or software cracks, which are almost always detected by anti-malware. Delete such files straight away, as cracks/keygens are the main distribution method for devastating infections such as Geno ransomware, which would encrypt all the files on your system and then demand ransom for their return.

Thus, if you are downloading new software, browsing the web, or are facing with a suspicious ad asking you to download an unknown program, always pay attention to your security software, as definitions are updated regularly, and there are plenty of invisible threats around that you would never notice without it.

From our report of Jan 2021 · not reviewed since

Handle Js/Adrozek.A virus detection correctly

False positives can be pretty hard to understand for regular computer consumers, and they can often be very damaging overall.

This is why independent testing labs always take into account a number of false-positives when ranking anti-malware software. While Windows Defender has been doing much better in this regard from a few years ago, false detections are still possible. So, you should not rush Js/Adrozek.A virus removal immediately.

To determine whether it is indeed a false positive, you should keep in mind several factors, for example, what were you doing during the time of the pop-up; if you were about to download software crack, you for sure remove Js/Adrozek.A without thinking twice.

However, if the detection is repeated at certain time periods and occurs when you are performing regular activities (for example, watching YouTube videos) or accessing a legitimate program (Opera), you should consider putting it as an exclusion via the security software settings.

From our report of Jan 2021 · not reviewed since

More from our earlier report on Js/Adrozek.A, BrowserModifier:JS/Adrozek.A, Trojan:Win32/Adrozek!rfn

• Such a sustained, far-reaching campaign requires an expansive, dynamic attacker infrastructure.
• We tracked 159 unique domains, each hosting an average of 17,300 unique URLs, which in turn host more than 15,300 unique, polymorphic malware samples on average.

From our report of Jan 2021 · not reviewed since

Js/Adrozek.A virus is a relatively old detection name used by Windows Defender to identify suspicious activity on various web browsers.

In most cases, such potentially unwanted programs are distributed via deceptive methods such as software bundling or fake update prompts - this usually results in unintentional installation. However, this threat is related to JavaScript malware, which typically infiltrates machines automatically. If anti-malware software is installed, it will block the threat and flag it as Js/Adrozek.A or BrowserModifier:JS/Adrozek.A.

While the heuristic detection Js/Adrozek.A is not new, there have been multiple reports about its increased activity. Security researchers from Microsoft have been investigating the campaign by cybercriminals - it was revealed that malware affects various browsers such as Google Chrome, MS Edge, Yandex, and Mozilla Firefox.

If the targeted machine is not protected, users could be subjected to extensive advertisements that would be shown at the top of regular search results. Ads are generated based on keywords that victims type into their searches, and each of such clicks would profit cybercriminals through affiliate advertising programs.

Another case could be attributed to security software flagging a false-positive. Users from Germany, Poland, and other countries reported that the popups were frequent as soon as the Opera web browser was used. Even though the detection should be investigated, it is highly likely that Adrozek popups are caused by an update of either Microsoft Defender definitions or the Opera web browser.

While Js/Adrozek.A virus is commonly used for describing browser hijacking actions; the detection name also indicates that the infection is related to JS, otherwise known as JavaScript. JavaScript is a programming language that is widely used on various web pages to make them interactive.

Nonetheless, the JavaScript is also commonly used to launch malicious attacks, which could result in malware infiltration, and, under certain circumstances, can occur without any user interaction whatsoever. To mitigate such attacks, it is important to ensure that all the software is updated, including the operating system, as the drive-by download would fail if no software vulnerabilities are found during it.

If the detection is not a false-positive, it is much more dangerous than a regular browser hijacker due to this, as it can establish persistence mechanisms, change the Windows registry, and perform other actions that would prevent an easy Js/Adrozek.A removal. If your anti-virus software is incapable of deleting the found threat, we highly advise you to try using an alternative solution, such as or .

Nonetheless, it is also important to note that Js/Adrozek.A virus detection can also be a false positive. These instances are relatively common (other common heuristic detections suffering from the same problem include Win32/Lodi, Js/Adware.Agent.AW, HTML:RedirME-inf, and many others) and often happen with when a particular program, in this instance, Opera, gets updated, and security application flags it mistakenly.

One of the main reasons why Js/Adrozek.A might be a false positive is when many users report the same activity on the same platform. Despite this, each of the heuristic detections should be carefully investigated to ensure that it is not indeed a false positive. For that, perform the following steps:

In case repeated scans with other anti-malware show that the detection is indeed a false positive, you should add the location/file to the exclusions list.

• Update security software and the related program, e.g., Opera
• Remove Js/Adrozek.A virus if other security programs detect it as well.