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How to avoid installation of Lucy ransomware

Also Known As: Lucy mobile ransomware
Type: Trojan
Damage level: Severe

What is Lucy?

Ransomware is malicious software that encrypts files stored on the infected device and keeps them inaccessible unless victims decrypt them with a specific tool (key, program). Typically, the attackers demand payment in exchange for a decryption tool.

Cyber criminals behind Lucy ransomware target Android users.

This ransomware encrypts files using an AES algorithm and appends the ".Lucy" extension to filenames. For example, "1.jpg" is renamed to "1.jpg.Lucy", "2.jpg" to "2.jpg.Lucy", and so on.

Lucy also displays a ransom message in a browser window. Note that this ransomware allows the attackers to control the infected device and install additional malware on it.

Lucy android malware

Lucy displays a ransom message designed as if delivered by the FBI (Federal Bureau of Investigation). It claims that files have been locked/encrypted because there are some suspicious files stored on the device, and forbidden pornographic websites have been visited.

The main point of Lucy's ransom message is to trick victims into believing that the FBI has information about them (including photos of their faces), and they must pay a fine by providing credit card details to regain access to their files.

As mentioned, cyber criminals behind Lucy can control infected devices by sending certain commands via a Command and Control (C&C) server.

Lucy can receive commands allowing cyber criminals to make phone calls, receive a list of installed applications, open a remote shell on the device, uninstall/remove Lucy from the infected device, collect a string called “key” for data encryption and use similar command for its decryption, generate messages claiming that the payment was declined, and clear elements containing encryption keys.

As mentioned, Lucy can receive commands from a C&C server that can decrypt encrypted files. After receiving information about successful data decryption, Lucy changes the command to remove it from the device.

Despite this, it is likely that cyber criminals behind do not actually decrypt files, and go on to remove Lucy, even if victims pay the ransom. Therefore, do not pay them for data decryption.

Unfortunately, it is impossible to restore access to files without the involvement of the attackers. Typically, the only way for victims to recover their files free of charge is to restore them from a backup.

Malware of this is capable of encrypting new files - this can be avoided by removing that malware from the infected device, however, already encrypted data remains inaccessible even when ransomware is no longer installed on the system.

Threat Summary:
Name Lucy mobile ransomware
Threat Type Android malware, mobile ransomware.
Detection Names Avast-Mobile (APK:Locker [Trj]), BitDefenderFalx (Android.Trojan.Botnet.F), ESET-NOD32 (A Variant Of Android/Spy.Banker.AKI), Kaspersky (HEUR:Backdoor.AndroidOS.Lucbot.e), Microsoft (Backdoor:AndroidOS/LucBot.B!MTB), Full List (VirusTotal)
Symptoms Cannot open files stored on your device, previously functional files now have a different extension (for example, my.docx.locked). A ransom demand message is displayed. Cyber criminals demand payment of a ransom (usually in bitcoins) to unlock your files.
Distribution methods Infected email attachments, malicious online advertisements, social engineering, deceptive applications, scam websites.
Damage All files are encrypted and cannot be opened without paying a ransom. Additional password-stealing trojans and malware infections can be installed together with a ransomware infection. Stolen personal information (private messages, logins/passwords, etc.), decreased device performance, battery is drained quickly, decreased Internet speed, large data losses, monetary losses, stolen identity (malicious apps can misuse communication apps).
Malware Removal (Android) To eliminate malware infections our security researchers recommend scanning your Android device with legitimate anti-malware software. We recommend Avast, Bitdefender, ESET or Malwarebytes.

More examples of mobile ransomware programs targeting Android users are Cyberpunk 2077 and Hackerz. Both mobile and desktop ransomware variants are similar: they encrypt files and display or create ransom messages with instructions about how to pay the ransom, contact the attackers, and various other details.

Main differences between ransomware variants are cryptographic algorithm that they use to encrypt files, decryption key, and program cost. Devices infected with ransomware are at risk, since it is virtually impossible to decrypt files free of charge, unless in rare cases the ransomware has certain vulnerabilities or there are third-party decryption tools available for download on the internet.

Therefore, maintain backups on remote servers (such as Cloud) or unplugged storage devices.

How did Lucy infiltrate my device?

It is likely that cyber criminals distribute this malware using social media links, Instant Messaging applications associated with this mobile Lucy ransomware variant, and a malicious video player application.

Research shows that one of the ways Lucy takes control over the device is by displaying a message asking for permission to enable Streaming Video Optimization. If allowed, Lucy ransomware gains permission to use the Accessibility Service.

It uses this service to start malicious services leading to the execution of the commands mentioned in above and encryption of the files stored on the infected device.

Note that cyber criminals can distribute mobile malware using malicious websites, SMS messages, phishing emails, and other channels. Sometimes they succeed at using Google Play to distribute their malware as well.

How to avoid installation of malware

To avoid infecting the system with malware spread through spam mail, you are strongly advised not to open suspicious or irrelevant emails, especially those with any attachments or links present in them. Use official and verified download channels.

Additionally, all programs must be activated and updated with tools/functions provided by legitimate developers, since illegal activation tools ("cracks") and third party updaters commonly proliferate malicious software.

To ensure device integrity and user safety, it is paramount to have reputable anti-virus/anti-spyware software installed and kept updated. Furthermore, use these programs to run regular system scans and to remove detected/potential threats.

Do not trust irrelevant emails that contain attachments or website links, especially if received from unknown, suspicious addresses.

Fake update tools infect systems by installing malicious programs rather than updates/fixes for installed software, or by exploiting bugs/flaws of outdated software that is installed on the computer.

Further encryption of any unaffected files can be prevented by uninstalling the ransomware, however, already compromised files remain encrypted even after removal of the rogue software and can only be recovered from a backup.

Screenshot of the files encrypted by Lucy Android ransomware:

lucy ransomware encrypted files

Quick menu:

Delete browsing history from the Chrome web browser:

Deleting web browsing history from Chrome in Android operating system (step 1)

Tap the "Menu" button (three dots on the right-upper corner of the screen) and select "History" in the opened dropdown menu.

Deleting web browsing history from Chrome in Android operating system (step 2)

Tap "Clear browsing data", select "ADVANCED" tab, choose the time range and data types you want to delete and tap "Clear data".

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Disable browser notifications in the Chrome web browser:

Disabling browser notifications in the Chrome browser in Android operating system (step 1)

Tap the "Menu" button (three dots on the right-upper corner of the screen) and select "Settings" in the opened drop-down menu.

Disabling browser notifications in the Chrome browser in Android operating system (step 2)

Scroll down until you see "Site settings" option and tap it. Scroll down until you see "Notifications" option and tap it.

Disabling browser notifications in the Chrome browser in Android operating system (step 3)

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 revisit the same site, 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).

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Reset the Chrome web browser:

Resetting Chrome browser to default in Android operating system (step 1)

Go to "Settings", scroll down until you see "Apps" and tap it.

Resetting Chrome browser to default in Android operating system (step 2)

Scroll down until you find "Chrome" application, select it and tap "Storage" option.

Resetting Chrome browser to default in Android operating system (step 3)

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.

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Delete browsing history from the Firefox web browser:

Delete browsing history from the Firefox in the Android operating system (step 1)

Tap the "Menu" button (three dots on the right-upper corner of the screen) and select "History" in the opened drop-down menu.

Delete browsing history from the Firefox in the Android operating system (step 2)

Scroll down until you see "Clear private data" and tap it. Select data types you want to remove and tap "CLEAR DATA".

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Disable browser notifications in the Firefox web browser:

Disable browser notifications in the Firefox web browser in the Android operating system (step 1)

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".

Disable browser notifications in the Firefox web browser in the Android operating system (step 2)

In the opened pop-up opt-in the "Notifications" option and tap "CLEAR".

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Reset the Firefox web browser:

Resetting Firefox browser in the Android operating system (step 1)

Go to "Settings", scroll down until you see "Apps" and tap it.

Resetting Firefox browser in the Android operating system (step 2)

Scroll down until you find "Firefox" application, select it and tap "Storage" option.

Resetting Firefox browser in the Android operating system (step 3)

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.

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Uninstall potentially unwanted and/or malicious applications:

Removing unwanted/malicious applications from the Android operating system (step 1)

Go to "Settings", scroll down until you see "Apps" and tap it.

Removing unwanted/malicious applications from the Android operating system (step 2)

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".

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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").

Booting Android device in Safe Mode

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.

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Check the battery usage of various applications:

Checking the battery usage of various applications in the Android operating system (step 1)

Go to "Settings", scroll down until you see "Device maintenance" and tap it.

Checking the battery usage of various applications in the Android operating system (step 2)

Tap "Battery" and check the usage of each application. Legitimate/genuine applications are designed to use as little 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.

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Check the data usage of various applications:

Checking data usage of various applications in the Android operating system (step 1)

Go to "Settings", scroll down until you see "Connections" and tap it.

Checking data usage of various applications in the Android operating system (step 2)

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 significant data usage may indicate presence of a 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.

Checking data usage of various applications in the Android operating system (step 3)

If you find an application that uses a lot of data even though you never use it, we strongly advise you to uninstall it as soon as possible.

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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 much more vulnerable, and so you should always be sure that your device software is up to date.

Installing software updates in the Android operating system (step 1)

Go to "Settings", scroll down until you see "Software update" and tap it.

Installing software updates in the Android operating system (step 2)

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.

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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 the 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 on. I.e., the device will be restored to its factory state.

You can also restore the basic system settings and/or simply network settings as well.

Resetting the Android operating system to its default (step 1)

Go to "Settings", scroll down until you see "About phone" and tap it.

Resetting the Android operating system to its default (step 2)

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;

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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 which apps have such privileges and disable the ones that should not.

Disabling Android applications that have administrator privileges (step 1)

Go to "Settings", scroll down until you see "Lock screen and security" and tap it.

Disabling Android applications that have administrator privileges (step 2)

Scroll down until you see "Other security settings", tap it and then tap "Device admin apps".

Disabling Android applications that have administrator privileges (step 3)

Identify applications that should not have administrator privileges, tap them and then tap "DEACTIVATE".

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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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