Chaos ransomware virus - removal and decryption options

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).

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.com

Payment 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.com

2- (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:

Update July 31, 2026 - Sophos researchers have documented a new Chaos ransomware campaign (tracked as STAC4749, active February to June 2026) targeting organizations in the United States and Canada through Microsoft Teams vishing calls. Attackers register fake IT helpdesk domains (such as sequrityupdate[.]top) and call employees over Teams while impersonating technical support staff.

Once on a call, the attackers convince targets to grant remote access via Microsoft Quick Assist, a built-in Windows screen-sharing tool. They then install additional remote access software, create hidden background processes for persistence, and deploy PowerShell-based backdoors - in some incidents progressing from initial contact to full ransomware deployment in under 17 hours.

Targeted sectors include services, manufacturing, energy, and construction. The threat actors are believed to be former members of the BlackSuit and Royal ransomware operations, both of which trace their origins to the Conti cybercrime organization. (source: bleepingcomputer.com).

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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Removal and file recovery procedure

If your files are encrypted with a new extension and a ransom note has appeared, you've been hit by ransomware. Don't pay. The procedure below works in order: contain the infection, identify the variant, remove the ransomware itself (so anything you restore doesn't get re-encrypted), and try to recover files using free decryption tools, Windows Volume Shadow Copies, or backups. Run a full system scan with Combo Cleaner to remove the infection - then move on to file recovery.

Common ransomware behaviors

VisibleEncrypts your files and renames them

The ransomware reads each file, encrypts the contents with the attacker's public key, and writes the encrypted bytes back to disk. Most variants also rename the file by appending a new extension - .net, .locked, .crypt, .lockbit, .djvu, etc. Without the matching private key, the encrypted files cannot be opened normally. Recovery depends on a free decryption tool, a recoverable Volume Shadow Copy, or a clean backup.

VisibleDrops a ransom note in every encrypted folder

A text or HTML file (usually named HOW_TO_DECRYPT.txt, README.txt, _readme.txt, or similar) is placed in every folder that contains encrypted files. The note explains the situation, lists a payment amount in cryptocurrency, gives a deadline, and provides a contact email or .onion site. Save the note - don't delete it. Its exact wording, the email address, and the bitcoin wallet are how you identify the variant in the next phase.

VisibleReplaces the desktop wallpaper

Many ransomware variants change the Windows wallpaper to a black or red image with the ransom message and instructions. The wallpaper is just a visual scare tactic - it doesn't add any actual capability and reverts to normal once the ransomware is removed. Photograph it before removal in case the contact details are useful for variant identification or for reporting to authorities.

HiddenDeletes Volume Shadow Copies

One of the first things modern ransomware does after launching is run vssadmin delete shadows /all /quiet to wipe Windows' built-in Volume Shadow Copies - the snapshots that Previous Versions and System Restore rely on. Some ransomware doesn't fully succeed (especially on systems where the user lacks full admin rights), leaving partial shadow copies recoverable. Phase 4 step 11 covers how to check what survived.

HiddenDisables Windows Defender and other security tools

Before encrypting, the ransomware tries to silence anything that could alert you or block it - Windows Defender real-time protection, third-party antivirus services, backup agents (Veeam, Acronis), and sometimes the Windows Event Log service. It often modifies Group Policy or registry keys to keep these off after reboot. Phase 3 step 9 explicitly turns Tamper Protection back on so the next ransomware attempt can't repeat the trick.

HiddenSpreads laterally to other PCs on the network

Network-aware ransomware (LockBit, Conti, BlackCat, Akira families) doesn't stop at the first machine. It scans for SMB shares, mapped drives, and other PCs on the same network, then encrypts whatever it can reach. On Windows domains, a single compromised user with admin rights can lead to all-domain encryption. This is why Phase 1 step 2 disconnects the network as the very first action - it stops the spread immediately.

HiddenSteals data before encrypting (double extortion)

Modern ransomware (LockBit, BlackCat / ALPHV, Akira, Cl0p, Royal) almost always exfiltrates data before encrypting. The attacker then runs a "double extortion" play: pay the ransom for decryption, plus pay again to prevent the stolen data from being leaked on the group's leak site. Paying the first ransom does not get the leaked data back - assume that anything the ransomware could read was uploaded. This is one more reason not to pay: the data is already out.

Tools you'll need

Combo Cleaner Antivirus 7-days free trial

Recommended primary scanner. VB100 certified. Removes the ransomware infection so file recovery doesn't get re-encrypted.

Microsoft Defender Offline Free · built-in

Built into Windows. Scans before Windows fully loads to catch persistence the running scanners miss.

Microsoft Safety Scanner (MSERT) Free

Microsoft's free on-demand scanner. Always-current signatures - the binary expires every 10 days.

ID Ransomware Free · web

Upload a ransom note and a sample encrypted file - identifies the variant family and tells you whether a free decryptor exists.

No More Ransom Project Free · web

Joint project of Europol, Dutch Police, and security vendors. Free decryption tools indexed by ransomware family.

Shadow Explorer Free

Browse Windows Volume Shadow Copies as a normal file tree - useful when ransomware partially failed to delete them.

Recuva Free

Deleted-file recovery. Long-shot for ransomware - only helps if the variant deleted unencrypted originals before encrypting copies.

Phase 1~ 5 min

Don't pay & contain

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1

Don't pay the ransom

1 min · read⚠ Do not skip

Paying the ransom does not guarantee you'll get your files back. Major ransomware response studies consistently show that a meaningful percentage of paying victims either receive a non-working decryptor, only partial decryption, or no decryptor at all. Beyond that:

• Paying confirms you as a willing target - re-attack rates within 12 months are high
• Several ransomware groups have been sanctioned (US OFAC, UK OFSI). Paying these groups may be illegal under sanctions law in your country
• The ransom funds the next attack - on you or someone else
• Modern ransomware almost always exfiltrates data first, so paying doesn't get the leaked data back. Assume anything the malware could read was uploaded
• Decryptors, even when they work, often leave files corrupted because the encryption itself was buggy or rushed

The path below tries every legal, free recovery option first. Pay only as an absolute last resort, after consulting a lawyer and your country's cyber crime authority.

2

Disconnect from the network and log out of cloud storage

2 minNo tool needed

Pull the Ethernet cable and turn off Wi-Fi on the affected PC. If multiple computers share the network, do the same on every machine you suspect could be affected, including any servers and NAS units.

Then sign out of cloud storage clients (OneDrive, Dropbox, Google Drive, iCloud) from their app settings. If you can, pause the sync. Some ransomware uses the running sync client to push encrypted versions over your clean cloud copies.

Why this matters

Modern ransomware spreads laterally across SMB shares, mapped drives, RDP, and reachable network neighbors. Disconnecting stops the spread the moment you do it. Logging out of cloud sync clients prevents the ransomware from encrypting the cloud copies of your files via the sync API.

3

Unplug external drives and USB storage

1 minNo tool needed

Safely eject any external drives, USB sticks, SD cards, and network-attached storage shares - then unplug them. If a drive was connected when the ransomware ran, the files on it may already be encrypted, but unplugging stops further damage.

Critically: don't reconnect any drive (including your most recent backup) to this PC until the ransomware is removed in Phase 3. Reconnecting an external backup to an actively-infected PC is the most common way that backup gets encrypted too.

Phase 2~ 5 min

Identify the variant

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4

Save the ransom note and a sample encrypted file

2 min

Copy the ransom note and one small encrypted file (under 1 MB) to a USB stick, or photograph the note with your phone. You'll need both for the variant identification step.

The ransom note is usually one of:

• A .txt file in every encrypted folder (typically HOW_TO_DECRYPT.txt, README.txt, or _readme.txt)
• An .html file with the same purpose
• A changed desktop wallpaper - photograph it
• A lock-screen interrupt that runs at startup - rarer

Important

Don't delete the note. Variant identification depends on its exact wording, the contact email, and the bitcoin wallet address. The note is also evidence if you report to authorities.

5

Identify the variant with ID Ransomware

Tool: ID Ransomware3 min

From a clean device (your phone is fine, or another PC that wasn't on the affected network), visit id-ransomware.malwarehunterteam.com. Upload the ransom note and the sample encrypted file. The site identifies the variant family and tells you whether a free decryptor exists.

Pro tip

ID Ransomware is run by the Malware Hunter Team. Files you upload are kept private - they're used for analysis, not published. If you're concerned about uploading data anyway, you can paste the contact email and bitcoin wallet from the note - those are often enough for identification.

Phase 3~ 30-45 min

Remove the ransomware

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The ransomware itself must be removed before any file recovery. If it's still active, anything you restore in Phase 4 gets re-encrypted within minutes.

6

Boot to Safe Mode with Networking and download the scanners

5 min

Safe Mode loads only the minimal Windows drivers, which prevents most ransomware from auto-running while you set up the scanners.

Windows 11: open Settings → System → Recovery, click Restart now next to Advanced startup. After the restart, click Troubleshoot → Advanced options → Startup Settings → Restart, then press 5 or F5.

Windows 10: click the Windows logo, hold Shift, click the Power icon and choose Restart. From the Choose-an-option screen, click Troubleshoot → Advanced options → Startup Settings → Restart, then press F5.

Once Safe Mode has loaded, turn Wi-Fi back on and download Combo Cleaner (used in step 8) and Microsoft Safety Scanner (used in step 9). Save both installers to your Desktop, then disconnect Wi-Fi again before scanning.

7

Run Microsoft Defender Offline

Tool: Built into Windows15 min

Reboot to normal Windows. Open Windows Security → Virus & threat protection → Scan options. Select Microsoft Defender Antivirus (offline scan) and click Scan now. The PC restarts into a stripped-down environment and scans the disk before Windows fully loads.

Why this comes first

Some ransomware variants drop bootkit components or kernel hooks that hide from any scanner running on the same Windows session that's already infected. A pre-boot offline scan sees the disk before the malware can load itself.

Recommended antivirus

Combo Cleaner

VB100 certified. Includes anti-trojan, registry/persistence scanning, and anti-spyware in one pass. The 7-day free trial is available.

Download Combo Cleaner

8

Run a full Combo Cleaner scan

Tool: Combo Cleaner20-40 min

Run the installer you downloaded in step 6 and start a full system scan (not the quick scan). Let it complete, review what it detected, and apply the recommended actions. Combo Cleaner quarantines the ransomware executable and the registry / scheduled-task entries that re-launch it on reboot.

9

Run Microsoft Safety Scanner and re-enable Defender

Tool: MSERT15 min

Run Microsoft Safety Scanner (MSERT.exe) as a second-opinion full scan. The binary expires every 10 days so the copy you downloaded has the latest signatures.

Once it finishes, open Windows Security → Virus & threat protection → Manage settings and confirm Real-time protection, Cloud-delivered protection, and Tamper Protection are all on. Many ransomware variants disable Defender during the attack - this is where you switch it back on so the next attempt can't repeat the trick.

Why a second scan

Different scanning engines catch different threats. Running an additional Microsoft scan after Combo Cleaner is the most underused verification step in malware removal - and free.

Phase 4~ 30-60 min · results vary

Try to recover files

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Try the steps in order. The first decryptor that works ends the recovery process - no need to do all four.

10

Check the No More Ransom Project for a free decryptor

Tool: nomoreransom.org★ Cleanest path if listed5 min

Visit nomoreransom.org and search the Decryption Tools list for the variant name returned by ID Ransomware. The project is run by Europol, the Dutch Police, and security vendors - everything listed is legitimate and free.

If a decryptor exists, download it onto a clean PC, copy it across, and follow its instructions exactly. Decryptors usually want you to point them at a sample encrypted file plus its known unencrypted version (sometimes any image you previously had a backup of works).

Free decryptors exist for parts of the STOP/Djvu, GandCrab, REvil, Avaddon, Conti and Hive families, among others. Most modern variants don't have public decryptors - if yours isn't listed, that's expected; move to the next step.

11

Try Windows Volume Shadow Copies

Tool: Shadow Explorer / vssadmin15 min

Windows automatically creates Volume Shadow Copies of files when System Restore points are made or scheduled backups run. Most ransomware tries to wipe these (vssadmin delete shadows /all /quiet), but the deletion sometimes fails partially - especially if the running user doesn't have full admin rights. When it does fail, snapshots survive that contain pre-encryption versions of your files.

First, check what's there. Open Command Prompt as Administrator and run:

vssadmin list shadows

If you see entries listed, shadow copies survived. To restore from them:

• Built-in: right-click any folder → Properties → Previous Versions tab. Pick a snapshot dated before the infection and restore.
• Better tool for browsing: install Shadow Explorer (free). It shows all snapshots as a normal file tree and lets you copy out only the files you want.

Why check this even when there's a decryptor

Shadow Copies recover the original files exactly, with no risk of decryption errors. If they survived, this is faster and cleaner than running a decryptor on the encrypted set.

12

Restore from cloud or external backup

Tool: your backup software30 min

If you have a backup that pre-dates the infection, this is the cleanest recovery available. Important precautions:

• Don't reconnect a backup drive until Phase 3 is complete. If the ransomware is still active, plugging in the backup encrypts it too.
• For cloud backups (OneDrive, Dropbox, Google Drive, iCloud), use the Version History feature to roll individual files back to pre-encryption versions.
• OneDrive specifically has a "Restore your OneDrive" feature: if it detected mass file changes, you can roll back the entire account up to 30 days. Sign in at OneDrive on the web, click the Settings gear, and choose Restore your OneDrive. Microsoft 365 subscribers also get ransomware detection alerts; non-subscribers get one free recovery.
• Verify the restored files open correctly before you delete the encrypted set. Test a few documents, photos, and any database / project files.

13

Try Recuva as a last-resort recovery

Tool: Recuva30 min

Recuva is a long shot, not a primary recovery tool. Most modern ransomware encrypts files in place - it reads the original, encrypts the data, and writes the encrypted bytes back to the same disk location. In that case, the original isn't deleted, just rewritten - and Recuva has nothing to find.

But for older or simpler variants that deleted originals before creating encrypted copies (rather than encrypting in place), Recuva can sometimes pull the originals from unallocated disk space. Worth trying as a last resort, especially before you use the disk much further.

If you try it:

• Stop using the disk as much as possible - every disk write reduces recovery odds
• Run Recuva from a USB stick, not from the affected disk
• Use Deep Scan mode (slower but the only mode worth running for this scenario)

Don't skip the steps above expecting Recuva to bail you out. It works in maybe 5-20% of cases, depending on the variant and how soon you try.

Phase 5~ 20 min + ongoing

Report & prevent re-infection

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14

Report the attack to authorities

10-20 min

Even if your files aren't recovered, your report helps authorities track variants, attribute groups, and warn future victims. In some jurisdictions (especially the US and UK) early reporting can sometimes help recall a wired ransom payment via banking partners.

United States: ic3.gov (FBI) + stopransomware.gov (CISA)

United Kingdom: reportfraud.police.uk (Report Fraud, the successor to Action Fraud) + NCSC

Canada: antifraudcentre.ca

Australia: ReportCyber

Spain: Policía Nacional (Oficina Virtual de Denuncias)

France: cybermalveillance.gouv.fr

Germany: BKA

Italy: Polizia Postale

Netherlands: Politie

Poland: CERT Polska

Portugal: CNCS

EU (other): your national CERT

Save the report number - banks, insurers, and credit bureaus will ask for it. If you operate a business, you may also have legal disclosure obligations (GDPR in the EU, state breach laws in the US) that run on a 72-hour clock.

15

Plan 3-2-1 backups going forward

30 min initial

The single best defense against ransomware is a tested backup. Use the 3-2-1 rule:

• 3 copies of your data
• 2 different storage media (e.g., internal drive + external drive)
• 1 offline / air-gapped copy (an external drive that isn't always connected)

Recommended cadence:

• Daily: cloud sync (OneDrive, Dropbox, Google Drive) - convenient, but vulnerable if the ransomware reaches the sync folder. The Version History feature is what saves you
• Weekly: external drive that you connect briefly, then disconnect - the air-gap is what protects against ransomware
• Monthly: a second external drive stored off-site (different physical location) - protects against fire, theft, flood

Important

Test the backup at least once. Open a few files from it, check sizes match, restore one to a different folder. An untested backup isn't a backup - it's a hope.

16

Patch the entry point and monitor for 30 days

5 min/day · 30 days

Most reinfections happen via the same vector that worked the first time. Until you've patched the entry point, watch for:

• Unusual disk activity, unexpected file modifications, or unfamiliar processes in Task Manager
• Unexpected reboots or new accounts you didn't create
• Defender or your antivirus turning itself off again

Common entry vectors and what to do about each:

• Phishing email with a malicious attachment - review email filters and train yourself / staff to recognise the patterns - see pcrisk's Phishing/Scam reference
• Exposed RDP with weak passwords - disable Remote Desktop from Settings → System → Remote Desktop if you don't need it. If you do, put it behind a VPN and require a long password plus MFA
• Unpatched VPN appliances or public-facing apps - check the vendor's advisories page and apply the latest firmware
• Cracked / pirated software - was the most common vector for STOP/Djvu in particular. Don't run software from torrent sites

Run a Combo Cleaner scan weekly for the first month. Update Windows, browsers, and applications aggressively.

Important: Removing a ransomware infection requires a full system scan, not a manual file delete. If you're not confident with the manual procedure, run an automated scan with Combo Cleaner and Windows Defender and stop there - that combination removes the vast majority of consumer ransomware variants. Then move to Phase 4 for file recovery, or to Phase 5 if your files are unrecoverable and you need to start fresh from a clean Windows install.

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.