Avoid data encryption by Lost_Files ransomware

Ransomware

Also Known As: Lost_Files virus

(updated)

Damage level:

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What is Lost_Files?

Discovered by Xavier Mertens, Lost_Files is malicious software classified as ransomware. Typically, software of this type is designed to encrypt victims' files and keep them unusable unless a ransom is paid. In fact, this particular ransomware does not encrypt files - it simply renames them several times and then deletes them.

This ransomware appends the ".Lost_Files_Encrypt" extension to each encrypted file. For example, "1.jpg" becomes "1.jpg.Lost_Files_Encrypt". It also creates the "Ransomware Lost Files Message.txt" containing a ransom message and displays another in a pop-up window.

Research shows that this ransomware infects computers through a malicious email attachment sent by cyber criminals. The attachment is disguised as a "Windows Security Scanner" supposedly designed to remove malicious software. When executed, however, it infects computers with Lost_Files ransomware.

Once a system is infected, Lost_Files creates the "Ransomware Lost Files Message.txt" file, which contains information about how to pay the ransom. To get more details, victims must execute an identical file that they will have opened just prior to computer infection with this ransomware.

Once executed, the file displays a pop-up window stating that all data was encrypted. To recover it, victims are encouraged to purchase a decryption tool at a cost equivalent to $500. The ransom must be paid in Bitcoins - the wallet address for payment is displayed in a pop-up window that appears after clicking the "Get Your Data Decrypted" button.

It also contains an email address (lost_files_ransom@secmail.pro) of the cyber criminals who designed this ransomware. As mentioned, unlike most ransomware-type programs, Lost_Files does not encrypt files, but simply deletes them. Despite this, victims are still asked to pay the ransom.

Cyber criminals should never be trusted. Do not pay them. They often provide no decryption tools even if victims meet all of their demands. In most cases, the only way to recover files without risking being scammed is to restore them from a backup.

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

Lost_Files decrypt instructions

Lost_Files ransomware is quite similar to other programs of this type including, for example, Kuub, Angus, and Proced. To prevent victims from accessing their data, ransomware encrypts files. Instructions about how to decrypt them can usually be found in a new text file and/or a pop-up window.

Common differences are usually size of ransom and encryption algorithm (symmetric or asymmetric) used to lock/encrypt data. In any case, encryptions are generally impossible to 'crack' and user are thus often tempted to purchase decryption tools from ransomware developers.

Otherwise, decryption can only be cracked in rare cases when ransomware is not finished, has bugs/flaws, etc. The other option is use a data backup, if one was created prior to computer infection. Therefore, always have your data backed up and keep it stored on a remote server or unplugged storage device.

How did ransomware infect my computer?

Cyber criminals proliferate Lost_Files ransomware through an email disguised as a message from Microsoft. In fact, this company has nothing do to with this scam. According to the email, the recipient's computer was infected with a Trojan that collected personal information such as credit card numbers and credentials of bank accounts.

To avoid having these details stolen, scammers offer to scan their systems with a 'security scanner', which will supposedly remove the aforementioned threat. The email includes a "Download" button, which downloads an archive file called WSS.zip. This contains another file named "Windows Security Scanner.exe", an executable file that installs Lost_Files ransomware.

Note that malicious programs can also be distributed in other ways. For example, through Trojans, untrustworthy download channels/sources, unofficial activation, and software updating tools. Trojans are malicious programs that cause chain infections. If installed, they install additional malware.

Third party downloaders, free file hosting websites, Peer-to-Peer networks (torrents, eMule), freeware download websites, and other similar channels can be used to distribute malicious software. They often contain malicious files that are disguised as legitimate.

People who open files that were downloaded from these sources often cause installation of malware. Unofficial software activation tools supposedly help users to bypass paid activation of licensed software, however, they can infect computers with malicious programs.

Fake software updaters install malicious software rather than updates, or they exploit bugs/flaws of outdated software that is already installed on the system.

Threat Summary:
Name Lost_Files virus
Threat Type Ransomware, Crypto Virus, Files locker, Wiper.
Encrypted Files Extension .Lost_Files_Encrypt
Ransom Demanding Message Ransomware Lost Files Message.txt and pop-up window.
Ransom Amount $500 in Bitcoins.
Cyber Criminal Contact lost_files_ransom@secmail.pro
Detection Names Avast (Win32:Trojan-gen), BitDefender (Generic.Ransom.Hiddentear.A.B2914DE7), ESET-NOD32 (A Variant Of MSIL/Filecoder.IX), Microsoft (Trojan:Win32/Tiggre!rfn), Full List Of Detections (VirusTotal)
Rogue Process Name Lost_Files
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.
Additional Information This ransomware is distributed though emails that are disguised as notifications regarding malware infections from Microsoft. Although the pop-up window claims that data is encrypted, Lost_Files actually renames files a number of times and eventually deletes them.
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.

Download Combo Cleaner

To use full-featured product, you have to purchase a license for Combo Cleaner. 7 days free trial available. Combo Cleaner is owned and operated by RCS LT, the parent company of PCRisk.com.

How to protect yourself from ransomware infections

Do not open attachments (or web links) that are attached to irrelevant emails. Typically, these emails are disguised as important, official, and so on. In most cases, they are sent from unknown, suspicious addresses. Update installed software through implemented functions or tools designed by official developers.

Files and programs should be downloaded only from official websites and via direct download links. Unofficial software activation ('cracking') tools are illegal and often lead to installation of malware.

Do not use these tools. Regularly scan the operating system using a reputable anti-virus or anti-spyware suite and remove detected threats immediately. If your computer is already infected with Lost_Files, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate this ransomware.

The appearance of Lost_Files ransomware pop-up (GIF):

Appearance of Lost_Files pop-up

Text presented by Lost_Files in a pop-up:

Attention!!! First of all we are terribly sorry to have encrypted your data. Because we are human too and we feel some guilt encrypting your data. We offer that we can help you decrypt it again for a small amount of Bitcoins(BTC).
The amount that we need from you is 500 USD that you will transfer to our BTC account. To Get your unique tool to decrypt your files, your need to push the button below and your BTC payment address will show, transfer 500 USD in BTC to that address.
After you have transfered the BTC you are going to send an email to our email address(Our email will also get displayed when pushed the button). Where you provide your BTC address of the wallet that you used to send our BTC(If you have other comments, you are welcome to say it)[Also remerber to check your spam inbox for when we send your decryption tool].
We will check it, if you have sent the BTC, you will get your decryption tool.                                                                                                    
Another thing to keep in mind is that, at some point you won't be able to get your data back again and it will be lost forever.
Everything from family memories to the hard work of yours, will be washed down the toilet and it will never return.
So it's strongly advised that you start paying us for helping you to decrypt it. In the case that you are a little older and don't know much about all the computer stuff then you can ask your children or grandchildren.
PLEASE Look below for additional information.
 
Needing help to get your BTC?
Some resources to get started with BTC:
hxxps://coinsutra.com/buy-bitcoin-uk/
hxxps://cryptocurrencytutors.com/getting-started-with-bitcoin/
hxxps://blokt.com/guides/10-best-bitcoin-cryptocurrency-exchanges-2019-proven-safe-exchanges

Keep in mind!
When you buy BTC you should buy slightly more than 500 USD, just in case the price drops. Also you need it as sending fees which varies at times. So it's recommended to buy 510 USD worth of BTC from one of the exchanges.
Then again we are sorry for what happened to you, hope you will have better luck next time! :)

Screenshot of Lost_Files text file ("Ransomware Lost Files Message.txt"):

Lost_Files text file

Text in this file:

Hi, This is Lost_Files Ransomware, Pay us 500 USD to get our decryption software.
So that you can get your files back. The payment is going to be paid in Bitcoin(BTC).
For more information about this please click the same EXE file you clicked when you
lost all your files. There will be detailed instruction there.

Screenshot of an email used to trick people into downloading a malicious file:

email that is used to distribute Lost_Files ransomware

Text presented within this email:

Microsoft
*** This is an automatic generated email, do not respond. ***

Hi,

This email has been sent to you, because your windows computer has contracted a trojan horse virus.
The trojan horse virus has been known for collecting information about you(This includes credit card numbers and bank account logins).
So we strongly advise you to block your credit cards and your bank account logins, that you have used on your computer.

Microsoft has developed a scanner that can help you terminate the trojan horse virus.
The scanner has been developed under safeplaces L.L.C. which is a Microsoft subsidiary.
It's important that you download and install it quickly, because the trojan horse virus will ruin your computer.

Here you can download the security scanner:

[Download]

*** This is an automatic generated email, do not respond. ***

90 York Street
Lakeland, Florida, 33801
United States

Screenshot of a malicious attachment - Windows Security Scanner.exe executable file designed to install Lost_Files:

Windows Security Scanner malicious executable desinged to infect computers with Lost_Files

Screenshot of Windows Security Scanner pop-up installing Lost_Files ransomware:

Lost_Files installation process 

Screenshot of malicious "Lost_Files" process running in Task Manager:

Lost_Files malicious process in Task Manager 

Screenshot of files renamed by Lost_Files (".Lost_Files_Encrypt" extension):

Files encrypted by Lost_Files

List of targeted file formats:

.ASP; .ASPX; .AVI; .BAT; .BMP; .CSS; .CSV; .DOC; .DOCX; .HTML; .JPEG; .JPG; .MDB; .MKV; .MOV; .MP3; .MP4; .MPEG; .ODT; .OGG; .PDF; .PHP; .PPT; .PPTX; .PSD; .RAR; .SQL; .TXT; .WAV; .WMA; .WMV; .XLS; .XLSX; .XML; .ZIP; .asp; .aspx; .avi; .bat; .bmp; .css; .csv; .doc; .docx; .html; .jpeg; .jpg; .mdb; .mkv; .mov; .mp3; .mp4; .mpeg; .odt; .ogg; .pdf; .php; .png; .ppt; .pptx; .psd; .rar; .sdf; .sql; .txt; .wav; .wma; .wmv; .xls; .xlsx; .xml; .xxx; .zip

Lost_Files 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.

File Explorer showing files with ransomware-encrypted extension
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.

Example ransom note text file with redacted contact information
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.

Example ransomware desktop wallpaper takeover
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.

Command prompt vssadmin list shadows output
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.

Windows Security with Defender disabled by malware
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.
Built into Windows. Scans before Windows fully loads to catch persistence the running scanners miss.
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.
Joint project of Europol, Dutch Police, and security vendors. Free decryption tools indexed by ransomware family.
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

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

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.

ID Ransomware identification result for a sample variant
Phase 3~ 30-45 min
Remove the ransomware

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.

Combo Cleaner full system scan results showing the detected ransomware family
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

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.

No More Ransom Project decryption tools list
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.

Shadow Explorer browsing pre-infection Volume Shadow Copies
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

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
Australia: ReportCyber
Germany: BKA
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.

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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.

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