Chaos ransomware virus - removal and decryption options
Written by Tomas Meskauskas on (updated)
What is Chaos ransomware?
Ransomware is malicious software that prevents victims from accessing their files by encrypting them and generates a ransom demanding message (for example, a text file). Chaos is an upgraded version of another ransomware variant called RYUK. This version replaces the extension of each encrypted file with a string of ransom characters.
For example, it renames a file named "1.jpg" to "1.jpg.us00", "2.jpg" to "2.jpg.0w2h", "3.jpg" to "3.jpg.wf1d", and so on. Chaos creates its ransom note (the "read_it.txt" text file) in all folders that have encrypted files in them.
Screenshot of files encrypted by Chaos (random extension):
Ransom note overview
In most cases, ransom notes generated by ransomware contain contact and payment information such as email address, price of a decryption tool, Bitcoin (or another cryptocurrency) wallet address, and so on. As written in the "read_it.txt" text file, Chaos ransomware encrypts all files, and it is impossible to decrypt them without the right decryption software that costs $1,500 (or 0.1473766 BTC). It is also stated that the attackers only accept Bitcoin.
The specified amount of Bitcoin has to be transferred to the provided BTC wallet address (it is provided at the bottom of the ransom note). To summarize, victims are instructed to pay a ransom and then wait for the decryption software that will encrypt files and uninstall Chaos ransomware from the operating system.
More about ransomware
Most ransomware variants encrypt files using strong cryptography. Therefore, ransomware victims cannot access their files without decrypting them with a specific decryption tool, and only the attackers have that tool.
In such cases, there is only one way to recover files without having to pay for it - to restore them from a backup. However, it is only possible to recover files this way when a data backup exists.
It is important to know that cybercriminals behind ransomware attacks cannot be trusted - they do not always send a decryption tool even if they get paid. In other words, paying a ransom does not guarantee that access to the files will be restored.
Another important detail about the malware of this type is that it can encrypt new files and install itself on other computers connected to the same network. This can be prevented by uninstalling ransomware. It is worth mentioning that files remain encrypted even when ransomware that has encrypted them is no longer installed.
In conclusion, most ransomware variants are used to extort money from victims by forcing them to pay for a decryption program or key that is supposed to restore access to files. It is worthwhile to mention that the only main differences between ransomware attacks are prices of decryption tools and cryptographic algorithms used to encrypt files.
In one way or another, victims of most ransomware attacks cannot decrypt files for free unless there is a free decryption tool on the Internet or the installed ransomware has some bugs, flaws. As mentioned in the introduction, most of the times the only free option is to restore files from an existing backup.
For this reason it is recommended to create data backups regularly and store them on a remote server like Cloud or unplugged storage device. A couple of examples of other ransomware variants are AXI, Exx, and CryT0Y.
How did ransomware infect my computer?
There are different ways to distribute malicious software. One of them is to trick recipients into opening malicious attachments or links in emails disguised as letters from legitimate companies or organizations.
In such cases, recipients install malware by downloading and opening malicious files, for example, Microsoft Office documents, JavaScript files, EXE and other executable files, contents extracted from ZIP, RAR, or other archive files, PDF documents. Another way to distribute malware is to design fake updaters or software 'cracking' tools to install malware.
Fake updaters are disguised as legitimate tools that are supposed to fix or update software. However, they are designed to infect computers by exploiting bugs, flaws of outdated software, or installing malicious software in a regular way.
Software 'cracking' tools are supposed to activate legitimate software without having to pay for it. There are two problems with these tools: it is not legal to use them, and they can be malicious.
Files downloaded from questionable, untrustworthy sources can be designed to install malware too. Typically, they are malicious files that look like legitimate, regular files.
Some examples of channels that cybercriminals use to trick users into infecting computers are Peer-to-Peer networks (e.g., torrent clients, eMule), third-party downloaders, free file hosting websites, freeware download pages, unofficial websites. One more popular way to distribute malware is to trick users into installing certain trojans.
Typically, cybercriminals use one of the aforementioned ways to distribute trojans. Once installed, those trojans can install their payload (for example, ransomware).
| Name | Chaos virus |
| Threat Type | Ransomware, Crypto Virus, Files locker |
| Encrypted Files Extension | Each encrypted file has a different random extension (e.g., .us00, .0w2h, .wf1d), .locked, .fu(ck)ed (without brackets), .Deadline, .owonegerpro |
| Ransom Demanding Message | read_it.txt, ENCRYPTED!!!!.txt |
| Ransom Amount | $1,500 or 0.1473766 BTC |
| Cryptowallet Addresses | bc1qw0ll8p9m8uezhqhyd7z459ajrk722yn8c5j4fg, bc1qrx0frdqdur0lllc6ezmv45hchdrg72ns7m6jmy, bc1qlnzcep4l4ac0ttdrq7awxev9ehu465f2, 19DpJAWr6NCVT2oAnWieozQPsRK7Bj83r4, bc1qn5cmjkju03h49ml659spkwhx7eyc6p3lmaf472, 357kKuBPCHbEN68fb6JsuryJFgmG53crAq, 0x337b368048eEaDD5F093F4c0341a488e34D3B41c, TGuGRctAhiYLg1dB6j2mZ8zBbqKqRz6Q8m, bc1qth4727vl3fnjwvv45matxku2crpjqjpsnp2n75, 17CqMQFeuB3NTzJ2X28tfRmWaPyPQgvoHV, 0xdF0f41d46Dd8Be583F9a69b4a85A600C8Af7f4Ad, bc1qv27ppgkfztdsqwxzswdkkhmc02alkx2vn5mtmx |
| Cybercriminals' Contacts | gdecryptor5@onionmail.org, gdecryptor5@yahoo.com, infoaboutransom@proton.me, yohos94948@nzaif.com, touch.tech900@proton.me |
| Detection Names | Avast (Win32:RansomX-gen [Ransom]), BitDefender (Generic.Ransom.HydraCrypt.F940D4B4), ESET-NOD32 (A Variant Of MSIL/Filecoder.AGP), Kaspersky (HEUR:Trojan.MSIL.Fsysna.gen), Microsoft (Ransom:Win32/Filecoder!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) | To eliminate possible malware infections, scan your computer with legitimate antivirus software. Our security researchers recommend using Combo Cleaner. |
How to protect yourself from ransomware infections?
As mentioned above, attachments and links in emails can be used to deliver malware. Typically, malicious emails are irrelevant to their recipients and sent from an unknown, suspicious address.
Therefore, it is strongly recommended not to open files in emails of this kind. Another recommendation is not to use third-party downloaders (or installers), unofficial pages, and other sources, tools of this kind to download or install programs (or download files).
Files and programs should be downloaded only from official websites (and via direct links). One more way to avoid malware is to activate and update installed software with tools provided by its official developers.
None of the other tools are trustworthy. Moreover, it is illegal to activate licensed software with 'cracking' tools. Additionally, it is recommended to scan the operating system for threats regularly and do it using a reputable antivirus or anti-spyware software.
If your computer is already infected with Chaos, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate this ransomware.
Screenshot of a message encouraging users to pay a ransom to decrypt their compromised data ("read_it"):
Text presented in Chaos ransomware's text file ("read_it.txt"):
----> Chaos is multi language ransomware. Translate your note to any language <----
All of your files have been encrypted
Your computer was infected with a ransomware virus. Your files have been encrypted and you won't
be able to decrypt them without our help.What can I do to get my files back?You can buy our special
decryption software, this software will allow you to recover all of your data and remove the
ransomware from your computer.The price for the software is $1,500. Payment can be made in Bitcoin only.
How do I pay, where do I get Bitcoin?
Purchasing Bitcoin varies from country to country, you are best advised to do a quick google search
yourself to find out how to buy Bitcoin.
Many of our customers have reported these sites to be fast and reliable:
Coinmama - hxxps://www.coinmama.com Bitpanda - hxxps://www.bitpanda.comPayment informationAmount: 0.1473766 BTC
Bitcoin Address: bc1qw0ll8p9m8uezhqhyd7z459ajrk722yn8c5j4fg
Screenshot of files encrypted by another variant of Chaos ransomware (".locked" extension):
Screenshot of a ransom note delivered by another variant of Chaos ransomware:
Text presented within:
ATTENTION GENTLEMEN!
All your files like documents, photos, databases and other important files have been encrypted by us!
We used the strongest millitary algorithms RSA4096 and AES-256.
No one can help you to restore files without our special decoder.The repair tools are useless and easily destroy your files irreversibly!
DO NOT...
...rename encrypted files, and do not use third party softwares to attemt the decryption by yourself!
Just do not waste your time, because nobody can recover your files without our decryption service.If you want to restore your files you should follow this steps:
1. Write an email to us to our contact. (email: infoaboutransom@proton.me)
2. You have to pay for decryption in Bitcoins what costs $1000~0.04 BTC. You should buy 0.04 BTC and send it to us at the attached address. Just search in Google, how to buy bitcoin, it is very fast and simple!
Address: 19DpJAWr6NCVT2oAnWieozQPsRK7Bj83r4
3. In your email, write to us your wallet address and a screenshot about your payment confirmation.
4. After payment we will send to you our special decoder frothwith to decrypt all of your files!P.S.
- We do not need your files and your information. You have 12 hours to complete the payment, or all of your files and keys will be deleted automatically. Just send a request immediately after infection.
- All data will be restored absolutely.
- We donate ALL incoming amounts anonymously to organizations, hospitals, etc.
- Nothing personal, just business.. Take care!R.H. Team
Screenshot of a ransom note delivered by another variant of Chaos ransomware:
Text presented within:
Don't worry, you can return all your files!
All your files like documents, photos, databases and other important are encrypted
You only have 96 hours to submit the payment. If you do not send money within provided time, all
your files will permanently crypted and n one will be able to recover them.You can send 3 of your encrypted files and we decrypt it for free.
You must follow these steps To decrypt your files :
1- Send your Transaction hash for our emaill : yohos94948@nzaif.com2- (You must to pay for decryption in Bitcoins.
After payment we will send you the tool that will decrypt all your files.)3- Send $100 For our Bitcoin or BNB Address or USDT-TRC20
Bitcoin: 19DpJAWr6NCVT2oAnWieozQPsRK7Bj83r4
BNB Smart Chain: 0x337b368048eEaDD5F093F4c0341a488e34D3B41c
USDT-TRC20 : TGuGRctAhiYLg1dB6j2mZ8zBbqKqRz6Q8m
Screenshot of a desktop wallpaper containing the exact same note used by this Chaos variant:
Chaos ransomware removal:
Instant automatic malware removal:
Manual threat removal might be a lengthy and complicated process that requires advanced IT skills. Combo Cleaner is a professional automatic malware removal tool that is recommended to get rid of malware. Download it by clicking the button below:
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Video suggesting what steps should be taken in case of a ransomware infection:
Quick menu:
- What is Chaos virus?
- STEP 1. Reporting ransomware to authorities.
- STEP 2. Isolating the infected device.
- STEP 3. Identifying the ransomware infection.
- STEP 4. Searching for ransomware decryption tools.
- STEP 5. Restoring files with data recovery tools.
- STEP 6. Creating data backups.
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):
USA - Internet Crime Complaint Centre IC3
United Kingdom - Action Fraud
Spain - Policía Nacional
France - Ministère de l'Intérieur
Germany - Polizei
Italy - Polizia di Stato
The Netherlands - Politie
Poland - Policja
Portugal - Polícia Judiciária
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: 
Click the "Change adapter settings" option in the upper-left corner of the window: 
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". 
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": 
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).
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).
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).
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):
Example 2 (.iso [Phobos] ransomware):
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.
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.
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:
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:
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 cloud icon to open the OneDrive menu. While in this menu, you can customize your file backup settings.
Click Help & Settings and then select Settings from the drop-down menu.
Go to the Backup tab and click Manage 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.
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.
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.
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.
To access files only located on OneDrive online, go to the Help & Settings drop-down menu and select View online.
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:
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.
Frequently Asked Questions (FAQ)
How was my computer hacked and how did hackers encrypt my files?
Users infect computers by opening files downloaded from unreliable sources (e.g., shady pages, third-party downloaders, P2P networks), malicious files or links received via email, through pages hosting pirated software, etc.
How to open files encrypted by Chaos ransomware?
Victims of ransomware attacks cannot open encrypted files. Those files must be decrypted before they can be opened.
Where should I look for free decryption tools for Chaos ransomware?
In case of a ransomware attack you should check the No More Ransom project website (more information above).
I can pay you a lot of money, can you decrypt files for me?
We do not provide a decryption service. Typically, victims are forced to pay cybercriminals to decrypt files (unless ransomware is flawed). Third parties offering paid decryption should not be trusted. Paying them can result in being scammed or paying or paying a man-in-the-middle.
Will Combo Cleaner help me remove Chaos ransomware?
Combo Cleaner will scan the operating system for threats and remove ransomware. It is important to remove ransomware to prevent further encryptions. However, antivirus software does not decrypt encrypted files.
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