How to remove the Tangeng ransomware?

Also Known As: Tangeng virus
Distribution: Low
Damage level: Severe

Tangeng ransomware removal instructions

What is Tangeng?

Tangeng is a type of malware that encrypts victim's files and then demands a payment to unlock (decrypt) files. In other words, it makes sure that a victim could not access, use files unless a ransom is paid. Tangeng also renames every encrypted file by appending the ".tangeng" extension to its filename (e.g., it renames "1.jpg" to "1.jpg.tangeng", "2.jpg" to "2.jpg.tangeng", and so on), generates ransom notes ("HOW_TO_DECYPHER_FILES.hta" and "HOW_TO_DECYPHER_FILES.txt" files). Tangeng creates the "HOW_TO_DECYPHER_FILES.txt" file in all folders that contain encrypted data. Judging by the HTML tags it can be assumed that ransomware developers either wanted to create HTML files instead of TXT files, or they mistakenly pasted the text from HTA to the TXT.

Tangeng's ransom notes are created to inform a victim that all documents, photos, databases, and other files are no longer accessible because they have been encrypted, and it is impossible to decrypt them without a decryption key that can be provided only by the developers of this ransomware. A victim is instructed to contact the attackers for instructions on how to purchase a decryption key via the datarecovery@asiarecovery.ir email address. It is stated that if a decryption key is not purchased within 12 hours after the attack, then its price will be raised, and if it is not purchased within 24 hours, then all files will be deleted. Additionally, a victim is warned no to try to rename encrypted files or try to decrypt them with third party software because it may cause permanent data loss.

Typically, when a victim's computer is infected with ransomware (victim's files are encrypted by ransomware), the only way to recover files for free is to restore them from a backup. In most cases, the attackers are the only ones who have the right decryption tools (software or key), and they are not giving them out for free. It is important to mention that victims can never know whether the attackers will send them decryption tools or not. Paying a ransom does not guarantee that cybercriminals will keep their word (send a decryption key or software). Therefore, it is strongly advisable not to pay a ransom and restore files from a backup, if there is one. It is noteworthy that when installed ransomware has not encrypted all files, then the loss of unencrypted files can be avoided by uninstalling ransomware from the operating system. However, its uninstallation does not make already encrypted files accessible.

Screenshot of a message encouraging users to pay a ransom to decrypt their compromised data:

Tangeng decrypt instructions (HOW_TO_DECYPHER_FILES.hta)

To sum up, ransomware is a form of malware that encrypts files and generates a ransom note demanding a payment to be made in order for the data to be accessible again. Two main differences between ransomware attacks usually are the size of a ransom (the price of decryption tools) and cryptographic algorithms that ransomware uses to encrypt files. The biggest problem with becoming a victim of a ransomware attack usually is that there is no way to decrypt files for free. It can be achieved without paying a random only when ransomware has some vulnerabilities and does not happen often. Therefore, users are advised to create data backups regularly and keep them stored on some remote server (e.g., Cloud) or unplugged storage device. More ransomware examples are DERZKO, Lucifer, and MILIHPEN.

How did ransomware infect my computer?

Ransomware can be distributed using malspam emails, fake software updating tools, Trojans, unreliable sources for downloading software, and software 'cracking' tools. Malspam emails are used to deliver malware via malicious attachments or website links. Either way, the purpose of such emails is to trick recipients into downloading and then opening a malicious file. Usually, cybercriminals use malicious Microsoft Office, PDF documents, JavaScript files, archive files like RAR, ZIP, or executable files (like .exe) to deliver malware via malspam. It is important to mention that most malspam emails are disguised as important, official letters from legitimate companies. Fake software updating tools are disguised as legitimate too. Although, if used, they either installing malware instead of updates, fixes for installed programs, or by exploiting bugs, flaws of installed programs that are out of date.

Trojan is a type of malware that can be designed to download its payload (install certain malware). In other words, certain Trojans can cause chain infections. However, this malware distribution method works only when cybecriminals successfully trick users into installing such Trojans on their computers. Unreliable sources for downloading files, software are various Peer-to-Peer networks (e.g., torrent clients, eMule), unofficial websites, freeware download sites, third party downloaders, etc. Their users infect computers with malware when they download and open malicious files. Usually, cybercriminals attempt to trick users into downloading those files by designing them to look like legitimate files. Unofficial software activation ('cracking') tools are supposed to activate licensed software illegally. However, the fact that such tools are not legal is not the only problem. It is common that they contain malware.

Threat Summary:
Name Tangeng virus
Threat Type Ransomware, Crypto Virus, Files locker
Encrypted Files Extension .tangeng
Ransom Demanding Message HOW_TO_DECYPHER_FILES.hta, HOW_TO_DECYPHER_FILES.txt
Cyber Criminal Contact datarecovery@asiarecovery.ir
Detection Names Avast (Win32:Trojan-gen), BitDefender (Trojan.MSIL.Basic.6.Gen), ESET-NOD32 (A Variant Of MSIL/Filecoder.Thanos.A), Kaspersky (HEUR:Trojan.MSIL.AntiAV.gen), Microsoft (Backdoor:Win32/Bladabindi!ml), Full List Of Detections (VirusTotal)
Symptoms Cannot open files stored on your computer, previously functional files now have a different extension (for example, my.docx.locked). A ransom demand message is displayed on your desktop. Cyber criminals demand payment of a ransom (usually in bitcoins) to unlock your files.
Distribution methods Infected email attachments (macros), torrent websites, malicious ads.
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.
Malware Removal (Windows)

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How to protect yourself from ransomware infections?

Do not open files and website links in irrelevant emails that are sent from unknown, suspicious addresses. Download files or software only from legitimate, official websites and via direct download links. Do not use other sources, channels like third party downloaders, unofficial pages, third party to downloaders to download software, or third-party installers to install the software. Update and activate installed software with tools or implemented functions that its official developers provide. Never use any third-party, unofficial tools neither to update or activate licensed software. Such tools tend to be malicious, and it is not legal to bypass software activations using 'cracking' tools. Scan the operating system with a reputable antivirus or anti-spyware software regularly and always keep that software up to date. If your computer is already infected with Tangeng, we recommend running a scan with Malwarebytes for Windows to automatically eliminate this ransomware.

Text in "HOW_TO_DECYPHER_FILES.hta" and "HOW_TO_DECYPHER_FILES.txt":

What Happen to my computer?
Your important files are encrypted. Many of your documents, photos, passwords, databases and other files are no longer accessible because they have been encrypted. Maybe you are busy looking for way to recover your files , but do not waste your time. Nobody can recover your files without our decryption KEY (if somebody will tell that they can do it, they will also contact me and I will make the price so much expensive than if you contact directly)
- Can i Recover My Files?
Sure. We guarantee that you can recover all your files safely and easily But You have not so enough time . So If you want to decrypt all your files, you need to pay . You only have 12H to submit the payment. After that price will be higher also, If the transaction is not completed within 24 hours your files will be permanently deleted.
Send e-mail to this address: datarecovery@asiarecovery.ir


You have to pay for decryption in Bitcoins.
How to obtain Bitcoins
How To buy bitcoins hxxps://buy.bitcoin.com/
The easiest way to buy bitcoins is LocalBitcoins site. You have to register, click 'Buy bitcoins', and select the seller by payment method and price.
hxxps://localbitcoins.com/buy_bitcoins
Also you can find other places to buy Bitcoins and beginners guide here:
hxxp://www.coindesk.com/information/how-can-i-buy-bitcoins/
Attention!
Do not rename encrypted files.
Do not try to decrypt your data using third party software, it may cause permanent data loss.
Decryption of your files with the help of third parties may cause increased price (they add their fee to our) or you can become a victim of a scam.

Key Identifier: -

Screenshot of the "HOW_TO_DECYPHER_FILES.txt" file:

tangeng ransomware ransom note (HOW_TO_DECYPHER_FILES.txt)

Screenshot of files encrypted by Tangeng (".tangeng" extension):

Files encrypted by Tangeng ransomware (.tangeng extension)

Tangeng ransomware removal:

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Reporting ransomware to authorities:

If you are a victim of a ransomware attack we recommend reporting this incident to authorities. By providing information to law enforcement agencies you will help track cybercrime and potentially assist in the prosecution of the attackers. Here's a list of authorities where you should report a ransomware attack. For the complete list of local cybersecurity centers and information on why you should report ransomware attacks, read this article.

List of local authorities where ransomware attacks should be reported (choose one depending on your residence address):

Isolating the infected device:

Some ransomware-type infections are designed to encrypt files within external storage devices, infect them, and even spread throughout the entire local network. For this reason, it is very important to isolate the infected device (computer) as soon as possible.

Step 1: Disconnect from the internet.

The easiest way to disconnect a computer from the internet is to unplug the Ethernet cable from the motherboard, however, some devices are connected via a wireless network and for some users (especially those who are not particularly tech-savvy), disconnecting cables may seem troublesome. Therefore, you can also disconnect the system manually via Control Panel:

Navigate to the "Control Panel", click the search bar in the upper-right corner of the screen, enter "Network and Sharing Center" and select search result: Disconnecting computer from the Internet (step 1)

Click the "Change adapter settings" option in the upper-left corner of the window: Disconnecting computer from the Internet (step 2)

Right-click on each connection point and select "Disable". Once disabled, the system will no longer be connected to the internet. To re-enable the connection points, simply right-click again and select "Enable". Disconnecting computer from the Internet (step 3)

Step 2: Unplug all storage devices.

As mentioned above, ransomware might encrypt data and infiltrate all storage devices that are connected to the computer. For this reason, all external storage devices (flash drives, portable hard drives, etc.) should be disconnected immediately, however, we strongly advise you to eject each device before disconnecting to prevent data corruption:

Navigate to "My Computer", right-click on each connected device, and select "Eject": Ejecting external storage devices

Step 3: Log-out of cloud storage accounts.

Some ransomware-type might be able to hijack software that handles data stored within "the Cloud". Therefore, the data could be corrupted/encrypted. For this reason, you should log-out of all cloud storage accounts within browsers and other related software. You should also consider temporarily uninstalling the cloud-management software until the infection is completely removed.

Identify the ransomware infection:

To properly handle an infection, one must first identify it. Some ransomware infections use ransom-demand messages as an introduction (see the WALDO ransomware text file below).

Identify ransomware-type infection (step 1)

This, however, is rare. In most cases, ransomware infections deliver more direct messages simply stating that data is encrypted and that victims must pay some sort of ransom. Note that ransomware-type infections typically generate messages with different file names (for example, "_readme.txt", "READ-ME.txt", "DECRYPTION_INSTRUCTIONS.txt", "DECRYPT_FILES.html", etc.). Therefore, using the name of a ransom message may seem like a good way to identify the infection. The problem is that most of these names are generic and some infections use the same names, even though the delivered messages are different and the infections themselves are unrelated. Therefore, using the message filename alone can be ineffective and even lead to permanent data loss (for example, by attempting to decrypt data using tools designed for different ransomware infections, users are likely to end up permanently damaging files and decryption will no longer be possible even with the correct tool).

Another way to identify a ransomware infection is to check the file extension, which is appended to each encrypted file. Ransomware infections are often named by the extensions they append (see files encrypted by Qewe ransomware below).

Identify ransomware-type infection (step 2)

This method is only effective, however, when the appended extension is unique - many ransomware infections append a generic extension (for example, ".encrypted", ".enc", ".crypted", ".locked", etc.). In these cases, identifying ransomware by its appended extension becomes impossible.

One of the easiest and quickest ways to identify a ransomware infection is to use the ID Ransomware website. This service supports most existing ransomware infections. Victims simply upload a ransom message and/or one encrypted file (we advise you to upload both if possible).

Identify ransomware-type infection (step 3)

The ransomware will be identified within seconds and you will be provided with various details, such as the name of the malware family to which the infection belongs, whether it is decryptable, and so on.

Example 1 (Qewe [Stop/Djvu] ransomware):

Identify ransomware-type infection (step 4)

Example 2 (.iso [Phobos] ransomware):

Identify ransomware-type infection (step 5)

If your data happens to be encrypted by ransomware that is not supported by ID Ransomware, you can always try searching the internet by using certain keywords (for example, a ransom message title, file extension, provided contact emails, crypto wallet addresses, etc.).

Search for ransomware decryption tools:

Encryption algorithms used by most ransomware-type infections are extremely sophisticated and, if the encryption is performed properly, only the developer is capable of restoring data. This is because decryption requires a specific key, which is generated during the encryption. Restoring data without the key is impossible. In most cases, cybercriminals store keys on a remote server, rather than using the infected machine as a host. Dharma (CrySis), Phobos, and other families of high-end ransomware infections are virtually flawless, and thus restoring data encrypted without the developers' involvement is simply impossible. Despite this, there are dozens of ransomware-type infections that are poorly developed and contain a number of flaws (for example, the use of identical encryption/decryption keys for each victim, keys stored locally, etc.). Therefore, always check for available decryption tools for any ransomware that infiltrates your computer.

Finding the correct decryption tool on the internet can be very frustrating. For this reason, we recommend that you use the No More Ransom Project and this is where identifying the ransomware infection is useful. The No More Ransom Project website contains a "Decryption Tools" section with a search bar. Enter the name of the identified ransomware, and all available decryptors (if there are any) will be listed.

Searching for ransomware decryption tools in nomoreransom.org website

Restore files with data recovery tools:

Depending on the situation (quality of ransomware infection, type of encryption algorithm used, etc.), restoring data with certain third-party tools might be possible. Therefore, we advise you to use the Recuva tool developed by CCleaner. This tool supports over a thousand data types (graphics, video, audio, documents, etc.) and it is very intuitive (little knowledge is necessary to recover data). In addition, the recovery feature is completely free.

Step 1: Perform a scan.

Run the Recuva application and follow the wizard. You will be prompted with several windows allowing you to choose what file types to look for, which locations should be scanned, etc. All you need to do is select the options you're looking for and start the scan. We advise you to enable the "Deep Scan" before starting, otherwise, the application's scanning capabilities will be restricted.

Recuva data recovery tool wizard

Wait for Recuva to complete the scan. The scanning duration depends on the volume of files (both in quantity and size) that you are scanning (for example, several hundred gigabytes could take over an hour to scan). Therefore, be patient during the scanning process. We also advise against modifying or deleting existing files, since this might interfere with the scan. If you add additional data (for example, downloading files/content) while scanning, this will prolong the process:

Recuva data recovery tool scan time

Step 2: Recover data.

Once the process is complete, select the folders/files you wish to restore and simply click "Recover". Note that some free space on your storage drive is necessary to restore data:

Recuva data recovery tool recovering data

Create data backups:

Proper file management and creating backups is essential for data security. Therefore, always be very careful and think ahead.

Partition management: We recommend that you store your data in multiple partitions and avoid storing important files within the partition that contains the entire operating system. If you fall into a situation whereby you cannot boot the system and are forced to format the disk on which the operating system is installed (in most cases, this is where malware infections hide), you will lose all data stored within that drive. This is the advantage of having multiple partitions: if you have the entire storage device assigned to a single partition, you will be forced to delete everything, however, creating multiple partitions and allocating the data properly allows you to prevent such problems. You can easily format a single partition without affecting the others - therefore, one will be cleaned and the others will remain untouched, and your data will be saved. Managing partitions is quite simple and you can find all the necessary information on Microsoft's documentation web page.

Data backups: One of the most reliable backup methods is to use an external storage device and keep it unplugged. Copy your data to an external hard drive, flash (thumb) drive, SSD, HDD, or any other storage device, unplug it and store it in a dry place away from the sun and extreme temperatures. This method is, however, quite inefficient, since data backups and updates need to be made regularly. You can also use a cloud service or remote server. Here, an internet connection is required and there is always the chance of a security breach, although it's a really rare occasion.

We recommend using Microsoft OneDrive for backing up your files. OneDrive lets you store your personal files and data in the cloud, sync files across computers and mobile devices, allowing you to access and edit your files from all of your Windows devices. OneDrive lets you save, share and preview files, access download history, move, delete, and rename files, as well as create new folders, and much more.

You can back up your most important folders and files on your PC (your Desktop, Documents, and Pictures folders). Some of OneDrive’s more notable features include file versioning, which keeps older versions of files for up to 30 days. OneDrive features a recycling bin in which all of your deleted files are stored for a limited time. Deleted files are not counted as part of the user’s allocation.

The service is built using HTML5 technologies and allows you to upload files up to 300 MB via drag and drop into the web browser or up to 10 GB via the OneDrive desktop application. With OneDrive, you can download entire folders as a single ZIP file with up to 10,000 files, although it can’t exceed 15 GB per single download.

OneDrive comes with 5 GB of free storage out of the box, with an additional 100 GB, 1 TB, and 6 TB storage options available for a subscription-based fee. You can get one of these storage plans by either purchasing additional storage separately or with Office 365 subscription.

Creating a data backup:

The backup process is the same for all file types and folders. Here’s how you can back up your files using Microsoft OneDrive

Step 1: Choose the files/folders you want to backup.

Click the OneDrive icon in the taskbar

Click the OneDrive cloud icon to open the OneDrive menu. While in this menu, you can customize your file backup settings.

Select Help & Settings and click Settings

Click Help & Settings and then select Settings from the drop-down menu.

Select the Backup tab and click Manage backup

Go to the Backup tab and click Manage backup.

Select folders to backup and click Start backup

In this menu, you can choose to backup the Desktop and all of the files on it, and Documents and Pictures folders, again, with all of the files in them. Click Start backup.

Now, when you add a file or folder in the Desktop and Documents and Pictures folders, they will be automatically backed up on OneDrive.

To add folders and files, not in the locations shown above, you have to add them manually.

Select a file manually and copy it

Open File Explorer and navigate to the location of the folder/file you want to backup. Select the item, right-click it, and click Copy.

Paste the copied file in the OneDrive folder to create a backup

Then, navigate to OneDrive, right-click anywhere in the window and click Paste. Alternatively, you can just drag and drop a file into OneDrive. OneDrive will automatically create a backup of the folder/file.

File statuses in OneDrive folder

All of the files added to the OneDrive folder are backed up in the cloud automatically. The green circle with the checkmark in it indicates that the file is available both locally and on OneDrive and that the file version is the same on both. The blue cloud icon indicates that the file has not been synced and is available only on OneDrive. The sync icon indicates that the file is currently syncing.

Click Help & Settings and click View Online

To access files only located on OneDrive online, go to the Help & Settings drop-down menu and select View online.

Click the Settings cog and click Options

Step 2: Restore corrupted files.

OneDrive makes sure that the files stay in sync, so the version of the file on the computer is the same version on the cloud. However, if ransomware has encrypted your files, you can take advantage of OneDrive’s Version history feature that will allow you to restore the file versions prior to encryption.

Microsoft 365 has a ransomware detection feature that notifies you when your OneDrive files have been attacked and guide you through the process of restoring your files. It must be noted, however, that if you don’t have a paid Microsoft 365 subscription, you only get one detection and file recovery for free.

If your OneDrive files get deleted, corrupted, or infected by malware, you can restore your entire OneDrive to a previous state. Here’s how you can restore your entire OneDrive:

restore-your-onedrive

1. If you're signed in with a personal account, click the Settings cog at the top of the page. Then, click Options and select Restore your OneDrive.

If you're signed in with a work or school account,  click the Settings cog at the top of the page. Then, click Restore your OneDrive.

2. On the Restore your OneDrive page, select a date from the drop-down list. Note that if you're restoring your files after automatic ransomware detection, a restore date will be selected for you.

3. After configuring all of the file restoration options, click Restore to undo all the activities you selected.

The best way to avoid damage from ransomware infections is to maintain regular up-to-date backups.

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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.

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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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Tangeng virus QR code
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