How to eliminate Necro Trojan from infected Android devices
Written by Tomas Meskauskas on (updated)
What kind of malware is Necro?
Necro is a Trojan that targets Android users. Threat actors deliver it via modified versions of well-known apps and those found on official app stores like Google Play. Necro uses certain techniques to hide its malicious payloads to evade detection and can perform various malicious activities.
Necro Trojan overview
One of Necro's functions is to display intrusive ads, which can lead to malicious web pages designed to distribute other malware, steal personal information, extract money, and more. Also, the Trojan collects various information from infected devices, including screen size, RAM, operating system version, and device identifiers like IMEI and IMSI.
Additionally, it may track interactions with ads and other applications. Necro sends the harvested information to a command-and-control (C2) server controlled by the attackers. Furthermore, Necro can download and run other programs on infected devices. It can also change the links that are displayed in a web browser to include extra information (e.g., confirmation codes for payments).
This allows the malware to trick users into subscribing to services without their knowledge or run additional malicious code when they click on specific links. It is important to mention that Necro's modular architecture enables its creators to update it regularly, allowing new malicious modules or features to be added.
This adaptability makes it particularly dangerous, as it can respond to security measures and continue to evolve.
| Name | Necro malware |
| Threat Type | Android malware, malicious application, Trojan |
| Detection Names (Necro Trojan) | Avast-Mobile (Android:Evo-gen [Trj]), Combo Cleaner (Android.Riskware.Agent.gVRKB), ESET-NOD32 (Android/TrojanDownloader.Necro.A), Ikarus (Trojan-Downloader.AndroidOS.Necro), Full List (VirusTotal) |
| Related Domain | spotiplus[.]xyz |
| Detection Names (spotiplus[.]xyz) | Forcepoint ThreatSeeker (Suspicious), Kaspersky (Malware), Full List Of Detections (VirusTotal) |
| Symptoms | The device is running slow, system settings are modified without user's permission, questionable applications appear, data and battery usage is increased significantly, browsers redirect to questionable websites, intrusive advertisements are delivered. |
| Distribution methods | Unofficial websites, legitimate apps on app stores, modified versions of popular apps. |
| Damage | Stolen personal information, decreased device performance, additional infections, battery is drained quickly, decreased Internet speed, huge data losses, monetary losses, stolen identity. |
| Malware Removal (Android) | To eliminate possible malware infections, scan your mobile device with legitimate antivirus software. Our security researchers recommend using Combo Cleaner. |
Conclusion
In conclusion, the Necro Trojan illustrates the evolving landscape of mobile malware, infiltrating unofficial modifications and legitimate applications. Its ability to collect data and execute malicious tasks highlights the need for increased caution and robust security practices.
Some examples of other malware targeting Android users are Ajina, SpyAgent, and EagleSpy.
How did Necro infiltrate my device?
Threat actors distribute the Necro Trojan primarily by embedding it in modified versions of popular applications, such as a Spotify mod called Spotify Plus, available on unofficial websites. These sites often claim that the mods are legitimate (not malicious) and offer additional features.
The Trojan can also infiltrate legitimate apps in official app stores, like Wuta Camera and Max Browser, which were found to contain the Necro loader in their code. In addition, infected WhatsApp mods are distributed through unofficial channels.
In addition to the previously mentioned mods, the Necro Trojan has also been discovered in various game modifications. Infected titles include popular games like Minecraft, Stumble Guys, Car Parking Multiplayer, and Melon Sandbox.
How to avoid installation of malware?
Always examine unexpected or unfamiliar emails and messages carefully before clicking on links or opening attachments. Utilize reliable antivirus or anti-malware software and make sure to have it always up to date. Perform regular system scans.
Only download apps and files from official websites and app stores. Be cautious with pop-ups, ads, links, or buttons on suspicious sites. Regularly update the operating system.
Screenshot of a website offering a modified version of Spotify app containing the Necro Trojan:
Screenshot of an app on Google Play infected with Necro Trojan:
Quick menu:
- Introduction
- How to delete browsing history from the Chrome web browser?
- How to disable browser notifications in the Chrome web browser?
- How to reset the Chrome web browser?
- How to delete browsing history from the Firefox web browser?
- How to disable browser notifications in the Firefox web browser?
- How to reset the Firefox web browser?
- How to uninstall potentially unwanted and/or malicious applications?
- How to boot the Android device in "Safe Mode"?
- How to check the battery usage of various applications?
- How to check the data usage of various applications?
- How to install the latest software updates?
- How to reset the system to its default state?
- How to disable applications that have administrator privileges?
Delete browsing history from the Chrome web browser:
Tap the "Menu" button (three dots on the right-upper corner of the screen) and select "History" in the opened dropdown menu.
Tap "Clear browsing data", select "ADVANCED" tab, choose the time range and data types you want to delete and tap "Clear data".
Disable browser notifications in the Chrome web browser:
Tap the "Menu" button (three dots on the right-upper corner of the screen) and select "Settings" in the opened dropdown menu.
Scroll down until you see "Site settings" option and tap it. Scroll down until you see "Notifications" option and tap it.
Find the websites that deliver browser notifications, tap on them and click "Clear & reset". This will remove permissions granted for these websites to deliver notifications. However, once you visit the same site again, it may ask for a permission again. You can choose whether to give these permissions or not (if you choose to decline the website will go to "Blocked" section and will no longer ask you for the permission).
Reset the Chrome web browser:
Go to "Settings", scroll down until you see "Apps" and tap it.
Scroll down until you find "Chrome" application, select it and tap "Storage" option.
Tap "MANAGE STORAGE", then "CLEAR ALL DATA" and confirm the action by taping "OK". Note that resetting the browser will eliminate all data stored within. This means that all saved logins/passwords, browsing history, non-default settings and other data will be deleted. You will also have to re-login into all websites as well.
Delete browsing history from the Firefox web browser:
Tap the "Menu" button (three dots on the right-upper corner of the screen) and select "History" in the opened dropdown menu.
Scroll down until you see "Clear private data" and tap it. Select data types you want to remove and tap "CLEAR DATA".
Disable browser notifications in the Firefox web browser:
Visit the website that is delivering browser notifications, tap the icon displayed on the left of URL bar (the icon will not necessarily be a "Lock") and select "Edit Site Settings".
In the opened pop-up opt-in the "Notifications" option and tap "CLEAR".
Reset the Firefox web browser:
Go to "Settings", scroll down until you see "Apps" and tap it.
Scroll down until you find "Firefox" application, select it and tap "Storage" option.
Tap "CLEAR DATA" and confirm the action by taping "DELETE". Note that resetting the browser will eliminate all data stored within. This means that all saved logins/passwords, browsing history, non-default settings and other data will be deleted. You will also have to re-login into all websites as well.
Uninstall potentially unwanted and/or malicious applications:
Go to "Settings", scroll down until you see "Apps" and tap it.
Scroll down until you see a potentially unwanted and/or malicious application, select it and tap "Uninstall". If, for some reason, you are unable to remove the selected app (e.g., you are prompted with an error message), you should try using the "Safe Mode".
Boot the Android device in "Safe Mode":
The "Safe Mode" in Android operating system temporarily disables all third-party applications from running. Using this mode is a good way to diagnose and solve various issues (e.g., remove malicious applications that prevent users you from doing so when the device is running "normally").
Push the "Power" button and hold it until you see the "Power off" screen. Tap the "Power off" icon and hold it. After a few seconds the "Safe Mode" option will appear and you'll be able run it by restarting the device.
Check the battery usage of various applications:
Go to "Settings", scroll down until you see "Device maintenance" and tap it.
Tap "Battery" and check the usage of each application. Legitimate/genuine applications are designed to use as low energy as possible in order to provide the best user experience and to save power. Therefore, high battery usage may indicate that the application is malicious.
Check the data usage of various applications:
Go to "Settings", scroll down until you see "Connections" and tap it.
Scroll down until you see "Data usage" and select this option. As with battery, legitimate/genuine applications are designed to minimize data usage as much as possible. This means that huge data usage may indicate presence of malicious application. Note that some malicious applications might be designed to operate when the device is connected to wireless network only. For this reason, you should check both Mobile and Wi-Fi data usage.
If you find an application that uses a lot of data even though you never use it, then we strongly advise you to uninstall it as soon as possible.
Install the latest software updates:
Keeping the software up-to-date is a good practice when it comes to device safety. The device manufacturers are continually releasing various security patches and Android updates in order to fix errors and bugs that can be abused by cyber criminals. An outdated system is way more vulnerable, which is why you should always be sure that your device's software is up-to-date.
Go to "Settings", scroll down until you see "Software update" and tap it.
Tap "Download updates manually" and check if there are any updates available. If so, install them immediately. We also recommend to enable the "Download updates automatically" option - it will enable the system to notify you once an update is released and/or install it automatically.
Reset the system to its default state:
Performing a "Factory Reset" is a good way to remove all unwanted applications, restore system's settings to default and clean the device in general. However, you must keep in mind that all data within the device will be deleted, including photos, video/audio files, phone numbers (stored within the device, not the SIM card), SMS messages, and so forth. In other words, the device will be restored to its primal state.
You can also restore the basic system settings and/or simply network settings as well.
Go to "Settings", scroll down until you see "About phone" and tap it.
Scroll down until you see "Reset" and tap it. Now choose the action you want to perform:
"Reset settings" - restore all system settings to default;
"Reset network settings" - restore all network-related settings to default;
"Factory data reset" - reset the entire system and completely delete all stored data;
Disable applications that have administrator privileges:
If a malicious application gets administrator-level privileges it can seriously damage the system. To keep the device as safe as possible you should always check what apps have such privileges and disable the ones that shouldn't.
Go to "Settings", scroll down until you see "Lock screen and security" and tap it.
Scroll down until you see "Other security settings", tap it and then tap "Device admin apps".
Identify applications that should not have administrator privileges, tap them and then tap "DEACTIVATE".
Frequently Asked Questions (FAQ)
My device is infected with Necro Trojan, should I format my storage device to get rid of it?
Formatting your storage device can remove malware, but it is a drastic step that should be taken only as a last resort. Instead, users are advised to employ a trusted antivirus or anti-malware software to eliminate Necro.
What are the biggest issues that malware can cause?
The harm caused by malware varies based on its type and functions. Common effects of malware attacks include identity theft, financial loss, further infections, data loss, and decreased device performance.
What is the purpose of Necro Trojan?
The purpose of Necro Trojan is to steal various information from infected devices and facilitate further malicious activities, such as downloading additional malware or executing arbitrary code.
How did Necro infiltrate my device?
Threat actors primarily spread the Necro Trojan by embedding it in modified versions of popular apps, like the Spotify Plus mod found on unofficial websites. The Trojan has also been found in legitimate apps on official app stores, such as Wuta Camera and Max Browser, as well as in various game mods for popular titles like Minecraft and Stumble Guys.
Will Combo Cleaner protect me from malware?
Yes, Combo Cleaner can detect and remove nearly all known malware infections. However, sophisticated malware often burrows deep within the system, so it is recommended that a full system scan be conducted.
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