Interlock (.interlock) ransomware virus – removal and decryption options

What kind of malware is Interlock?

Interlock is a ransomware that encrypts files and demands payment for the decryption. In addition to a Windows variant, there is a version of Interlock targeting Linux operating systems.

When we executed a sample of this ransomware on our test machine, it encrypted files and added a ".interlock" extension to their filenames. For example, a file originally named "1.jpg" appeared as "1.jpg.interlock", "2.png" as "2.png.interlock", etc. Afterward, Interlock dropped a ransom note titled "!__README__!.txt". Double extortion is also used to force victims into paying.

Interlock ransomware targets large entities and has been used in attacks leveraged against US governmental organizations and companies operating within the healthcare and technology spheres. Additionally, the malware was used to target manufacturing companies in Europe. However, Interlock attacks appear opportunistic and not exclusive to these sectors.

Screenshot of files encrypted by Interlock ransomware:

Ransom note overview

Interlock ransomware's message informs the victim that their organization network has been breached. Important files were encrypted, and sensitive data was exfiltrated (e.g., backups, business-critical files, contracts, legal and financial documents, personal data, client information, etc.).

The victim is given 96 hours to contact the attackers. By complying with the cyber criminals' demands, the victim will receive the decryption tools, and the stolen information will be deleted. If they refuse to cooperate, the vulnerable data will be leaked or sold, and media outlets, regulators, and competitors will be alerted of the attack.

Additionally, the victim is warned against modifying the affected files (i.e., renaming, moving, attempting decryption, etc.), as that will render them undecryptable.

Interlock ransomware overview

The functionality of Interlock's Windows and Linux versions is essentially the same. Significant similarities are to be found in how these programs carry out encryptions based on multithreading, check parameters, and self-delete following encryption. Naturally, some of the variation is due to the environment being different operating systems.

The Windows variant is better geared towards anti-detection, as it recovers the executable's original code before executing it (code patching). While the Linux version first checks the execution arguments. Checking arguments is how both operate prior to determining the further course of action.

Encryption arguments are the same in both: either only a specific file is encrypted, or all files in a directory and its subdirectories are. If neither argument is used, then everything is encrypted (barring exceptions): in Windows – from the C drive's top directory; in Linux – from the root directory.

OS differences dictate those in the file and directory exclusion lists; the goal of the malware is to avoid rendering the infected device inoperable or otherwise causing issues.

The Windows version alone utilizes a persistence-ensuring mechanism that involves registering and deleting tasks with Task Scheduler. The way these variants approach self-deletion differs; one significant difference is that the Windows version also eliminates logs from the Event Viewer.

The manner in which the Windows variant operates leaves little room for stopping the attack midway, while the Linux version may be limited. This variant could be blocked from further encryption by restricting the file and folder permissions to the user account. Additionally, an EDR (Endpoint Detection and Response) solution could be able to prevent this version from executing malicious processes or to create a software safelist that only permits pre-approved applications to run.

In most ransomware infections, decryption is impossible without the attackers' interference. The rare exceptions are cases involving deeply flawed ransomware.

However, paying does not guarantee data recovery since cyber criminals often do not send the promised decryption key/software despite receiving the ransom. Therefore, we strongly advise against complying. Remember that sending money to criminals supports their illegal activities.

To prevent Interlock ransomware from further encryptions – it must be eliminated from the network. Unfortunately, removal will not restore already locked files.

The only solution is to recover them from a backup (if one is available). Keep in mind that it is best practice to keep backups in multiple different locations, such as remote servers, unplugged storage devices, and others.

Ransomware examples

Kasper, Weaxor, Nyxe, and Heda are merely a few of our latest articles on ransomware. While this malware operates practically the same throughout (i.e., data encryption for ransom demands), there are two major differences.

These programs can use different cryptographic algorithms (symmetric or asymmetric) to encrypt data. Ransoms can differ significantly (from three to eight digits in USD) depending on the intended victim – home users vs. large entities (e.g., companies, organizations, institutions, etc.).

How did ransomware infect my computer?

In the known Interlock attacks, this ransomware was infiltrated into systems using a RAT (Remote Access Trojan). The trojan was proliferated under the guise of a fake Google Chrome browser update promoted on a legitimate news website that had been hacked.

The RAT did download a genuine Chrome setup, but it also executed embedded PowerShell scripts to download/install a credential-targeting stealer and a keylogger (program for recording keyboard input).

Stolen credentials, RDP (Remote Desktop Protocol) services, and programs like AnyDesk and PuTTY – were used to move between systems. In one of the attacks, the infection and data collection took over two weeks before Interlock was executed and the encryption began.

It must be mentioned that other techniques and infection chains could be used by Interlock. Generally, malware is proliferated using phishing and social engineering tactics. Malicious programs are usually disguised as or bundled with ordinary content.

Infectious files can be executables (.exe, .run, etc.), archives (RAR, ZIP, etc.), documents (Microsoft Office, Microsoft OneNote, PDF, etc.), JavaScript, and so on. Merely opening a virulent file can be enough to trigger the infection.

Malware is primarily distributed via trojans, drive-by (stealthy/deceptive) downloads, online scams, malicious attachments/links in spam mail (e.g., emails, PMs/DMs, SMSes, etc.), malvertising, untrustworthy download channels (e.g., freeware and third-party sites, P2P sharing networks, etc.), illegal software activation tools ("cracks"), and fake updates.

Some malicious programs can even self-spread via local networks and removable storage devices (e.g., external hard drives, USB flash drives, etc.).

How to protect yourself from ransomware infections?

We strongly recommend downloading only from official and verified sources. Additionally, all programs must be activated and updated using legitimate functions/tools, as those acquired from third-parties can contain malware.

Another recommendation is to be vigilant when browsing since the Internet is rife with fraudulent and malicious content. We advise approaching incoming emails and other messages with caution. Attachments or links present in suspicious/irrelevant mail must not be opened, as they can be infectious.

It is essential to have a reputable anti-virus installed and kept updated. Security software must be used to run regular system scans and to remove detected threats and issues. If your computer is already infected with Interlock, we recommend running a scan with Combo Cleaner Antivirus for Windows to automatically eliminate this ransomware.

Appearance of Interlock ransomware's text file "!__README__!.txt" (GIF):

Text presented in this message:

INTERLOCK - CRITICAL SECURITY ALERT

To Whom It May Concern,
Your organization has experienced a serious security breach. Immediate action is required to mitigate further risks. Here are the details:

THE CURRENT SITUATION
- Your systems have been infiltrated by unauthorized entities.
- Key files have been encrypted and are now inaccessible to you.
- Sensitive data has been extracted and is in our possession.

WHAT YOU NEED TO DO NOW
1. Contact us via our secure, anonymous platform listed below.
2. Follow all instructions to recover your encrypted data.

Access Point: -
Use your unique Company ID: -

 

DO NOT ATTEMPT:
- File alterations: Renaming, moving, or tampering with files will lead to irreversible damage.
- Third-party software: Using any recovery tools will corrupt the encryption keys, making recovery impossible.
- Reboots or shutdowns: System restarts may cause key damage. Proceed at your own risk.

HOW DID THIS HAPPEN?
We identified vulnerabilities within your network and gained access to critical parts of your infrastructure. The following data categories have been extracted and are now at risk:
- Personal records and client information
- Financial statements, contracts, and legal documents
- Internal communications
- Backups and business-critical files
We hold full copies of these files, and their future is in your hands.

YOUR OPTIONS
#1. Ignore This Warning:
- In 96 hours, we will release or sell your sensitive data.
- Media outlets, regulators, and competitors will be notified.
- Your decryption keys will be destroyed, making recovery impossible.
- The financial and reputational damage could be catastrophic.

 

#2. Cooperate With Us:
- You will receive the only working decryption tool for your files.
- We will guarantee the secure deletion of all exfiltrated data.
- All traces of this incident will be erased from public and private records.
- A full security audit will be provided to prevent future breaches.

FINAL REMINDER
Failure to act promptly will result in:
- Permanent loss of all encrypted data.
- Leakage of confidential information to the public, competitors, and authorities.
- Irreversible financial harm to your organization.

CONTACT US SECURELY
1. Install the TOR browser via hxxps://torproject.org
2. Visit our anonymous contact form at -
3. Use your unique Company ID: -
4. Review a sample of your compromised data for verification.
5. Use a VPN if TOR is restricted in your area.

Screenshot of Interlock's chat website on Tor network:

Screenshot of a ransom note ("OPEN_BEFORE_ANYTHING.txt") delivered by another variant of Interlock ransomware:

Text presented within:

We have successfully breached your network, encrypted your files, and obtained highly sensitive data. This is the result of weak cybersecurity on your part. As of now, your access to critical business information has been revoked. The only way to regain control is through cooperation. If you fail to contact us within 72 hours, we will proceed to publish your data to the public, ensuring severe consequences for your organization. By not addressing this matter, you risk violating major laws such as GDPR, GLBA, HIPAA, CCPA, NYDFS Cybersecurity Regulation, and DPA 2018. Such violations can result in massive fines, lawsuits, and irreparable harm to your reputation. It is your organization's responsibility to protect Non-Public Information (NPI); neglecting this duty has led to this situation.

To resolve this issue, visit our secure negotiation portal using the TOR Browser. Download TOR from [https://www.torproject.org](https://www.torproject.org), and access
-. Use your Organization ID
- to initiate communication. If you
prefer, you can also use standard browsers like Chrome, Edge, or Firefox and go to
-, where your ID will allow
you to proceed. Do not attempt to recover files on your own or involve third parties, as these actions will void the opportunity to resolve this matter and could lead to permanent data loss. Failure to act will escalate the situation, exposing your data to competitors, regulators, and the media. Your future depends on your decision now-act responsibly before the deadline passes.

Update May 6, 2025 – new tools and methods have been introduced to Interlock proliferation. The cyber criminals behind this ransomware continue to use fake updates as a lure; known samples played on the names of legitimate software, including Cisco, Fortinet, GlobalProtect, Ivanti, Webex, Zoom, etc. It has been observed that the initial access into targeted systems was achieved through ClickFix scams. New information-stealing malware has been introduced into these attacks – Lumma stealer and BerserkStealer.

Video showing how to remove Interlock ransomware using Combo Cleaner:

Interlock ransomware removal:

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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?

Interlock ransomware has been observed being proliferated via a fake browser update carrying a RAT (Remote Access Trojan). Other distribution methods are possible. Generally, malware is spread through trojans, drive-by downloads, online scams, dubious download sources (e.g., freeware and free file-hosting sites, P2P sharing networks, etc.), fake updaters, illegal program activation tools ("cracks"), spam mail, and malvertising.

How to open ".interlock" files?

Continued file usage necessitates decryption. In other words, encrypted files cannot be opened/used unless they are decrypted.

Where should I look for free decryption tools for Interlock ransomware?

In case of a ransomware attack, we advise looking up 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 decryption services. In fact, recovering ransomware-encrypted files is usually impossible without the attackers' interference. Therefore, third-parties offering paid decryption are often scams or aim to act as middlemen between victims and criminals.

Will Combo Cleaner help me remove Interlock ransomware?

Combo Cleaner will scan your device and eliminate active ransomware infections. It must be stressed that running a full system scan is crucial since sophisticated malicious programs typically hide deep within systems.