Horsia ransomware: what it is and how to remove it

That depends on the family behind the .horsia extension, which this guide cannot confirm yet from the reports alone. Check No More Ransom and ID Ransomware with your ransom note and one encrypted file; they list families with free tools.

If none exists today, keep the encrypted files and a copy of the note on a separate drive, because decryptors are sometimes published months later after flaws are found or servers are seized. Never buy a decryptor from a website that is not the security company that made it.

You cannot open them by renaming or by choosing another program. The .horsia ending shows that Horsia encrypted the content, and only the matching key can reverse it. Renaming a file back to .docx or .jpg changes nothing except the icon, and it can confuse a future decryptor, so leave the names as they are.

To get the content back, use a backup, an unencrypted copy elsewhere, or a decryptor listed on No More Ransom if one exists for Horsia. Store the encrypted files on an external disk until then.

We advise against it, and so do the FBI, Europol and national cyber agencies. Payment does not guarantee a working tool: some attackers never reply, some tools damage files, and some variants have no decryptor at all. Paying also funds further attacks and can make you a target again.

Before considering payment, try every recovery option in this guide and report the attack. Companies must involve their legal adviser and insurer, because payments to sanctioned groups can be illegal. If files are truly irreplaceable, store the encrypted copies and wait; decryptors sometimes appear later.

We do not know yet. Nothing published so far shows data theft by Horsia, but the only confirmed sign is files that end in .horsia and no longer open, which says nothing about what happened before. Many current ransomware attacks copy files or run a password stealer first, so it is wise to act as if they did.

From a clean device, change the passwords that were saved in the browsers on this PC, starting with e-mail and banking, sign out of all sessions and turn on two-step verification. Watch bank statements and account activity for the next few weeks.

Only if a decryptor already exists or the company pays the attackers for you. Some "ransomware recovery" services advertise that they can decrypt families with no known flaw; in practice they negotiate with the attackers and add their own fee. Others use the same free tools listed on No More Ransom.

Before you hire anyone, ask in writing how they will recover the files, whether they will contact the attackers and what happens if they fail. A legitimate service answers clearly. If a free decryptor exists for your family, you can run it yourself.

The way Horsia spreads has not been documented yet, so look at your own recent activity. On home PCs, ransomware most often comes with cracked programs, game cheats, key generators and fake updates, or with an e-mail attachment that was opened. On business networks, attackers usually log in through Remote Desktop with a stolen or guessed password.

Think back to what was downloaded or installed in the days before files that end in .horsia and no longer open, and check the Downloads folder and Installed apps sorted by date. Keep anything suspicious for your report, but do not run it again.

Not necessarily. Ransomware names come from the file extension, the note or a word in the code, so unrelated families often end up with similar names, and one family can appear under several names. The difference matters: a decryptor or advice for one family does not fit another and can damage files.

Compare the ending added to your files and the exact name of the note with the summary table at the top of this guide, then upload the note and one encrypted file to ID Ransomware from a clean device. If the result names another family, follow the guide for that family instead.

Quite a lot. The file name HOW TO RECOVER ENCRYPTED FILES.TXT, the wording, the contact addresses and the format of the personal ID are typical for each family. Uploading the note together with one encrypted file to ID Ransomware or No More Ransom's Crypto Sheriff usually names the family within seconds.

That name decides your options: some families have free decryptors, some can be partially recovered, and some cannot be decrypted at all. The note's claims about stolen data should be taken seriously but not at face value.

It can. Ransomware encrypts every drive and network share it can reach while it runs, so external disks, USB sticks and shared folders connected during the attack may also have files ending in .horsia. Disconnect everything now, then check each device from a clean computer.

Do not plug a backup drive into the infected PC until the ransomware has been removed with an offline scan. Cloud folders such as OneDrive sync the encrypted versions, but they keep earlier versions you can usually restore.

Fortect scans Windows for malware and unwanted programs and repairs the system files and settings they change, and its free scan shows what it finds on your PC before you decide anything.

For Horsia, follow the plan above as well: the browser steps take back permissions and settings that no scanner treats as a threat, and uninstalling the program that brought it removes the source.

Run Microsoft Defender's full scan and, if anything was found, its offline scan as a second opinion. If the symptoms are gone after the plan and both scans are clean, there is nothing more to do.