Some URL shortener providers distribute Android malware, including banking or SMS trojans

On iOS we’ve got seen hyperlink shortener providers pushing spam calendar information to victims’ units.

We hope you already know that you simply shouldn’t click on simply any URLs. You is perhaps despatched one in a message; someone may insert one underneath a social media submit or you might be provided with one on principally any website. Users or websites providing these links may use URL shortener providers. These are used to shorten lengthy URLs, cover unique domains, view analytics concerning the units of tourists, or in some instances even monetize their clicks.

Monetization signifies that when somebody clicks on such a link, an advertisement, such as the examples in Determine 1, shall be displayed that may generate revenue for the one that generated the shortened URL. The issue is that a few of these link shortener providers use aggressive advertising methods comparable to scareware advertisements: informing customers their units are infected with dangerous malware, directing customers to download dodgy apps from the Google Play retailer or to take part in shady surveys, delivering adult content, offering to start out premium SMS service subscriptions, enabling browser notifications, and making dubious gives to win prizes.

We’ve even seen hyperlink shortener providers pushing “calendar” information to iOS units and distributing Android malware – certainly, we discovered one piece of malware we named Android/FakeAdBlocker, which downloads and executes further payloads (corresponding to banking trojans, SMS trojans, and aggressive adware) acquired from its C&C server.

Under we describe the iOS calendar-event-creating downloads and easy methods to recuperate from them, before spending a lot of the blogpost on an in depth evaluation of the distribution of Android/FakeAdBlocker and, based mostly on our telemetry, its alarming number of detections. This evaluation is especially targeted on the performance of the adware payload and, since it could create spam calendar occasions, we’ve included a quick guide detailing learn how to routinely remove them and uninstall Android/FakeAdBlocker from compromised units.

Figure 1. Examples of shady aggressive ads


Content material displayed to the victim from monetized hyperlink shorteners can differ based mostly on the operating working system. As an example, if a victim clicked on the identical hyperlink on a Home windows system and on a cellular system, a unique website can be displayed on each system. In addition to websites, they might additionally supply an iOS system consumer to download an ICS calendar file, or an Android system consumer to obtain an Android app. Figure 2 outlines options we now have seen in the campaign analyzed here.

Figure 2. Malware distribution course of

While some ads and Android purposes served by these monetized shortened hyperlinks are official, we observed that the majority lead to shady or undesirable conduct.

iOS targets

On iOS units, in addition to flooding victims with unwanted advertisements, these websites can create occasions in victims’ calendars by mechanically downloading an ICS file. Because the screenshots in Determine three show, victims should first tap the subscribe button to spam their calendars with these occasions. Nevertheless, the calendar identify “Click OK To Continue (sic)” shouldn’t be revealing the true content of those calendar events and only misleads the victims into tapping the Subscribe and Accomplished button.

These calendar occasions falsely inform victims that their units are contaminated with malware, hoping to induce victims to click on on the embedded hyperlinks, which lead to more scareware ads.

Determine three. Rip-off website requests consumer to subscribe to calendar occasions on iOS platform

Android targets

For victims on Android units, the state of affairs is more harmful because these rip-off websites may initially provide the sufferer with a malicious app to obtain and afterwards proceed with visiting or downloading the actual expected content material looked for by the consumer.

There are two situations for Android users that we noticed during our analysis. Within the first one, when the sufferer needs to download an Android software aside from from Google Play, there is a request to allow browser notifications from that website, followed by a request to download an software referred to as adBLOCK app.apk. This may create the phantasm that this adBLOCK app will block displayed ads in the future, however the opposite is true. This app has nothing to do with the respectable adBLOCK software out there from the official supply.

When the consumer taps on the download button, the browser is redirected to a unique website where the consumer is seemingly provided an ad-blocking app named adBLOCK, however ends up downloading Android/FakeAdBlocker. In other words, the victim’s faucet or click on is hijacked and used to obtain a malicious software. If the victim returns to the previous page and faucets on the same obtain button, the right authentic file that the meant victim needed is downloaded onto the gadget. You’ll be able to watch one of many examples in the video under.

In the second Android state of affairs, when the victims need to proceed with downloading the requested file, they are proven an internet web page describing the steps to obtain and set up an software with the identify Your File Is Ready To Obtain.apk. This identify is clearly deceptive; the identify of the app is making an attempt to make the consumer assume that what is being downloaded is the app or a file they needed to access. You possibly can see the demonstration in the video under.

In each instances, a scareware commercial or the identical Android/FakeAdBlocker trojan is delivered by way of a URL shortener service. Such providers make use of the Paid to click on (PTC) enterprise mannequin and act as intermediaries between clients and advertisers. The advertiser pays for displaying advertisements on the PTC web site, where part of that cost goes to the celebration that created the shortened hyperlink. As said on one among these link shortening web sites within the privateness policy part, these advertisements are by way of their advertising partners and they don’t seem to be chargeable for delivered content or visited web sites.

One of many URL shortener providers states in its phrases of service that customers shouldn’t create shortened links to transmit information that include viruses, adware, adware, trojans or different dangerous code. To the contrary, we’ve got noticed that their ad partners are doing it.


Based mostly on our detection knowledge, Android/FakeAdBlocker was spotted for the primary time in September 2019. Since then, we have now been detecting it beneath numerous menace names. From the beginning of this yr until July 1st, we’ve seen greater than one hundred fifty,000 situations of this menace being downloaded to Android units.

Figure 4. ESET detection telemetry for Android/FakeAdBlocker

Determine 5. Prime ten nations by proportion of Android/FakeAdBlocker detections (January 1st – July 1st 2021)

Android/FakeAdBlocker analysis

After downloading and installing Android/FakeAdBlocker, the consumer may understand that, as seen in Determine 6, it has a white clean icon and, in some instances, even has no app identify.

Determine 6. App icon of Android/FakeAdBlocker

After its initial launch, this malware decodes a base64-encoded file with a .dat extension that is saved in the APK’s belongings. This file incorporates C&C server info and its inner variables.

Figure 7. Decoded config file from APK belongings

From its C&C server it’s going to request another configuration file. This has a binary payload embedded, which is then extracted and dynamically loaded.

Determine 8. Android/FakeAdBlocker downloads a further payload

For a lot of the examples we’ve got observed, the this payload was answerable for displaying out-of-context advertisements. Nevertheless, in tons of of instances, totally different malicious payloads have been downloaded and executed. Based mostly on our telemetry, the C&C server returned totally different payloads based mostly on the situation of the system. The Cerberus banking trojan was downloaded to units in Turkey, Poland, Spain, Greece and Italy. It was disguised as Chrome, Android Replace, Adobe Flash Player, Replace Android, or Google Guncelleme app (guencelleme is Turkish for “update” so the identify of the app is Google Replace). In Greece we now have also seen the Ginp banking trojan being downloaded. The same malware family variant of SMS trojan was distributed in the Middle East. Apart from these trojans, Bitdefender Labs additionally identified the TeaBot (also called Anatsa) banking trojan being downloaded as a payload by Android/FakeAdBlocker. Payloads are downloaded to exterior media storage in the information subdirectory of the father or mother app package deal identify utilizing numerous app names. An inventory of payload APK names is included within the IoCs part.

The rising incontrovertible fact that the C&C server can at any time distribute totally different malicious payloads makes this menace unpredictable. Since all aforementioned trojans have already been analyzed, we’ll continue with the analysis of the adware payload that was distributed to more than ninety nine% of the victims. The adware payload bears many code similarities with the downloader so we’re classifying each in the same Android/FakeAdBlocker malware family.

Though the payloads download within the background, the victim is informed about actions occurring on the cellular gadget by the activity displayed saying file is being downloaded. Once the whole lot is about up, the Android/FakeAdBlocker adware payload asks the victim for permission to draw over different apps, which can later end in it creating pretend notifications to show ads within the foreground, and for permission to access the calendar.

Determine 9. Exercise proven after begin

Figure 10. Permission request to regulate what is displayed in foreground

Figure 11. Permission request to edit calendar events

In any case permissions are enabled, the payload silently begins to create occasions in Google Calendar for upcoming months.

Determine 12. Scareware calendar occasions created by malware (above) and detail (under)

It creates eighteen events occurring each day, each of them lasts 10 minutes. Their names and descriptions recommend that the victim’s smartphone is contaminated, consumer knowledge is uncovered on-line or that a virus safety app is expired. Descriptions of each event embrace a hyperlink that leads the victim to go to a scareware advertisement web site. That web site again claims the system has been contaminated and gives the consumer to obtain shady cleaner purposes from Google Play.

Determine thirteen. Titles and descriptions of the events (left) and the reminder displayed by one among them (proper)

All the event title names and their descriptions might be found the malware’s code. Listed here are all scareware occasion texts created by the malware, verbatim. In case you discover one in every of these in your Google Calendar, you’re or have been probably a victim of this menace.
⚠ Hackers might attempt to steal your knowledge!
Block advertisements, viruses and pop-ups on YouTube, Fb, Google, and your favourite websites. CLICK THE LINK BELOW TO BLOCK ALL ADS

⚠ YOUR Gadget could be infected with A VIRUS ⚠
Block advertisements, viruses and pop-ups on YouTube, Fb, Google, and your favourite websites. CLICK THE LINK BELOW TO BLOCK ALL ADS

☠️Severe Viruses have been found lately on Android units
Block advertisements, viruses and pop-ups on YouTube, Fb, Google, and your favourite web sites. CLICK THE LINK BELOW TO BLOCK ALL ADS

🛑 Your Telephone just isn’t Protected ?! Click To Shield it!
It’s 2021 and also you haven’t discovered a method to shield your Gadget? Click under to repair this!

⚠ Android Virus Protection Expired ?! Renew for 2021
We’ve got all heard stories about people who acquired uncovered to malware and expose their knowledge in danger. Don’t be silly, shield yourself now by clicking under!

⚠ You Might Be Uncovered Online Click To Fix!
Hackers can examine the place you live by checking your system’s IP when you are at house. Shield yourself by installing a VPN. Shield your self by clicking under.

✅ Clear Your Gadget from Malicious Attacks!
Your Gadget just isn’t invincible from viruses. Make it possible for it’s free from an infection and stop future assaults. Click on the hyperlink under to start out scanning!

⚠ Viruses Alert – Verify Safety NOW
Hackers and practically anyone who need it might examine the place you reside by breaking into your system. Shield your self by clicking under.

☠️ Viruses on your System?! CLEAN THEM NOW
It’s 2021 and also you haven’t found a approach to shield your System? Click under to fix this!

🛡️ Click on NOW to Shield your Priceless Knowledge!
Your id and different necessary info may be simply stolen online with out the correct protection. VPN can effectively avoid that from occurring. Click on under to avail of that wanted safety.

⚠ You Are Uncovered On-line, Click on To Repair!
Hackers can verify where you reside by checking your system’s IP when you are at residence. Shield your self by installing a VPN. Shield your self by clicking under.

🧹 Clean your Telephone from potential threats, Click on Now.
Logging on exposes you to varied dangers together with hacking and different fraudulent actions. VPN will shield you from these attacks. Make your on-line searching secured by clicking the link under.

🛑 Your Telephone shouldn’t be Protected! Click To Shield it!
It’s 2021 and you haven’t discovered a approach to shield your iPhone? Click on under to repair this!

⚠ YOUR Gadget might be contaminated with A VIRUS ⚠
Block advertisements, viruses and pop-ups on YouTube, Fb, Google, and your favourite websites. CLICK THE LINK BELOW TO BLOCK ALL ADS

⚠ You Might Be Uncovered On-line Click on To Fix!
Hackers can verify the place you live by checking your gadget’s IP while you’re at house. Shield your self by putting in a VPN. Shield your self by clicking under.

☠️Extreme Viruses have been found lately on Android units
Block advertisements, viruses and pop-ups on YouTube, Facebook, Google, and your favourite websites. CLICK THE LINK BELOW TO BLOCK ALL ADS

☠️ Viruses in your Gadget?! CLEAN THEM NOW
It’s 2021 and you haven’t found a approach to shield your System? Click on under to fix this!

⚠ Android Virus Safety Expired ?! Renew for 2021
We have now all heard stories about people who acquired exposed to malware and expose their knowledge in danger. Don’t be silly, shield your self now by clicking under!

Apart from flooding the calendar with scam occasions, Android/FakeAdBlocker also randomly displays full display ads inside the cellular browser, pops up scareware notifications and adult ads, and shows a Messenger-like “bubble” within the foreground mimicking a acquired message with a scammy text subsequent to it.

Determine 14. Examples of displayed scareware advertisements

Clicking on any of those would lead the consumer to an internet site with further scareware content that means that the sufferer install cleaners or virus removers from Google Play. We now have already written about comparable shady apps impersonating security software in 2018.

Uninstall course of

To determine and remove Android/FakeAdBlocker, including its dynamically loaded adware payload, it’s essential to first find it among your installed purposes, by going to Settings -> Apps. As a result of the malware doesn’t have an icon or an app identify (see Figure 15), it ought to be straightforward to identify. Once situated, tap it once to pick it after which faucet on Uninstall button and ensure the request to take away the menace.

Determine 15. Guide uninstallation of malware

Tips on how to routinely remove spam occasions

Uninstalling Android/FakeAdBlocker won’t remove the spam events it created in your calendar. You’ll be able to take away them manually; nevertheless, it might be a tedious job. This process can be completed routinely, utilizing an app. During our checks we efficiently removed all these occasions using a free app out there from the Google Play retailer referred to as Calendar Cleanup. An issue with this app is that it removes only previous events. Because of that, to take away upcoming occasions, briefly change the current time and date in the settings of the gadget to be the day after the final spam event created by the malware. That might make all these occasions expired and Calendar Cleanup can then routinely take away them all.

It is very important state that this app removes all occasions, not just those created by the malware. Due to that, you need to rigorously select the focused vary of days.

As soon as the job is completed, be sure to reset the current time and date.


Based mostly on our telemetry, it appears that many users are likely to obtain Android apps from outdoors of Google Play, which might cause them to obtain malicious apps delivered by way of aggressive advertising practices which are used to generate income for their authors. We identified and demonstrated this vector of distribution in the videos above. Android/FakeAdBlocker downloads malicious payloads offered by its operator’s C&C server; normally, after launch these cover themselves from consumer view, deliver unwanted scareware or adult content material ads and create spam calendar occasions for upcoming months. Trusting these scareware advertisements may cost their victims cash either by sending premium price SMS messages, subscribing to pointless providers, or downloading further and sometimes malicious purposes. Apart from these situations, we identified numerous Android banking trojans and SMS trojans being downloaded and executed.


Hash Detection identify
B0B027011102B8FD5EA5502D23D02058A1BFF1B9 Android/FakeAdBlocker.A
E51634ED17D4010398A1B47B1CF3521C3EEC2030 Android/FakeAdBlocker.B
696BC1E536DDBD61C1A6D197AC239F11A2B0C851 Android/FakeAdBlocker.C



File paths of downloaded payloads


MITRE ATT&CK methods

This table was constructed utilizing model 9 of the ATT&CK framework.

Tactic ID Identify Description
Preliminary Access T1476 Ship Malicious App by way of Different Means Android/FakeAdBlocker could be downloaded from third-celebration web sites.
T1444 Masquerade as Respectable Software Android/FakeAdBlocker impersonates reliable AdBlock app.
Persistence T1402 Broadcast Receivers Android/FakeAdBlocker listens for the BOOT_COMPLETED broadcast, making certain that the app’s functionality can be activated each time the gadget begins.
T1541 Foreground Persistence Android/FakeAdBlocker displays transparent notifications and pop-up ads.
Defense Evasion T1407 Download New Code at Runtime Android/FakeAdBlocker downloads and executes an APK filefiles from a malicious adversary server.
T1406 Obfuscated Information or Info Android/FakeAdBlocker stores base64-encoded file in belongings containing config file with C&C server.
T1508 Suppress Software Icon Android/FakeAdBlocker’s icon is hidden from its sufferer’s view.
Collection T1435 Access Calendar Entries Android/FakeAdBlocker creates scareware occasions in calendar.
Command And Management T1437 Commonplace Software Layer Protocol Android/FakeAdBlocker communicates with C&C by way of HTTPS.
Impression T1472 Generate Fraudulent Advertising Revenue Android/FakeAdBlocker generates income by mechanically displaying advertisements.

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