.Ooss file extension. Remove Ooss virus. Restore, Decrypt .ooss files.

Ooss file extension

.Ooss file extension is a filename extension that is appended to the name of files affected by the latest version of STOP (djvu) ransomware. Ransomware is a malware that encrypts victims’ files and thus locks up the information contained in them. Ransomware developers demand a ransom in exchange for a decryptor and a key, which are necessary for decrypting the files. Fortunately, since Ooss is one of the variants of STOP (djvu), in some cases you can use the free STOP (Ooss) decryptor to decrypt files affected by it. More details about this decryptor, as well as other ways of recovering encrypted files, will be discussed in this article.

Ooss virus

Ooss virus is malware that is the 208th variant of STOP (DJVU) ransomware. Like other versions of this ransomware, it is distributed through key generators, cracked software, adware and torrents web-sites. Upon execution, Ooss creates a folder in the Windows system directory and copies itself there. Then the virus changes some Windows OS settings so that it starts automatically every time the PC is turned on or restarted.

Having collected information about the victim’s computer, Ooss virus tries to establish a connection with its command-and-control server (C&C). If the connection has been established, the virus receives a key (so called ‘online key’) from the command server that will be used to encrypt files. In addition, Ooss virus may receive additional commands and files that will be executed on the victim’s computer. If the virus could not connect to the command server, then it uses a fixed key, which the security researchers called ‘offline key’.

There is a significant difference between ‘online key’ and ‘offline key’. The online key is unique for each victim, that is, the key from one victim will not help decrypt the files of the other victim. The offline key is the same for all victims. Thus, it can be used to decrypt files regardless of where they were encrypted.

Having a key to encrypt files, Ooss virus proceeds directly to the process of encrypting files. It encrypts file-by-file, so that all files of the victim will be encrypted. It doesn’t matter where the files are located, on the internal drive, flash drive, external media, cloud storage, all of them can be encrypted. There is a small exception, the virus does not encrypt files located in the Windows system directories, files with the extension from the list ‘.lnk, .bat, ini, .sys, .dll’ and files with the name ‘_readme.txt’. Thus, almost all of the victim’s data will be encrypted, including documents, pictures, databases, archives and other types of files, such as:

.der, .mcmeta, .crt, .dmp, .dazip, .psk, .pptx, .csv, .itdb, .yml, .xx, .zi, .bar, .jpe, .syncdb, .xf, .xbdoc, .p7b, .avi, .arw, .xyw, .forge, .xy3, .mlx, .p7c, .ltx, .pef, .wp6, .wps, .mdf, .raw, .pdf, .xlsx, .rim, .wbz, .qic, .wri, .jpeg, .lrf, .accdb, .lvl, .2bp, .xlsm, .bc7, .das, .wmo, .iwi, .wpb, .xld, .orf, .xxx, .wbmp, .itm, .ai, .rwl, .xls, .ysp, .wpw, .eps, .vdf, .doc, .x, .wp7, .jpg, .hkx, .wmd, .ppt, .m4a, .mdb, .txt, .x3d, .rgss3a, .desc, .crw, .psd, .xml, .gho, .hkdb, .z, .xwp, .sid, .layout, .xar, .vpp_pc, .w3x, .yal, .mp4, .iwd, .css, .mddata, .py, .raf, .mef, .ybk, .xmind, .p12, .zdc, .rb, .pdd, .xyp, .wbd, .wpd, .wp, .mov, .vtf, .xlgc, .pkpass, .bsa, .esm, .cfr, .3dm, .sql, .wbk, .big, .itl, .x3f, .upk, .png, .y, .slm, .indd, .db0, .sidn, .xdb, .cer, .docm, .r3d, .wpg, .xls, .re4, .sis, .sb, .xdl, .wpd, .menu, .dng, .litemod, .ncf, .dcr, .xlsb, .qdf, .svg, .apk, .rtf, .xmmap, .ws, .wn, .wmf, .sum, .zw, .docx, .snx, .ff, .t13, .kf, .zabw, .pem, .dbf, .wb2, .srw, .fos, .tor, .ntl, .1st, .wdb, .zdb, .wbm, .ptx, .dwg, .xpm, .fsh, .xlsm, .7z, .pptm, .wpa, .wma, .js, .fpk, .wsd, .odm, .wps, .odc, .wot, .sie, .vcf, .wdp, .m2, .wotreplay, .wbc, .t12, .wp4, .wpl, .kdc, .zif, .wma, .odb, .asset, .m3u, .tax, .wsh, .rofl, .pfx, .wcf, .hplg, .sav, .0, .bkp, .ods, .zip, .bay, .ztmp, .wpt, .vfs0, .cas, .cdr, .xlsx, .xbplate, .odp, .xlk, .erf, .mrwref, .nrw, .wm, wallet, .wp5, .gdb, .hvpl, .kdb, .wav, .wmv, .dxg, .bkf, .rw2, .rar, .arch00, .icxs, .dba, .ibank, .d3dbsp, .wsc, .wpe, .wmv, .z3d, .epk, .vpk, .webdoc, .webp, .blob, .lbf, .wgz, .3ds, .x3f, .srf, .zip, .pak, .mdbackup, .sidd, .cr2, .1, .pst, .sr2, .bik

Each file that has been encrypted by Ooss virus will be renamed. It will append the extension ‘.ooss’ at the end of the name of the affected file. Thus, a file named ‘image.jpg’, after it is encrypted, will receive the name ‘image.jpg.ooss’. To encrypt as many files as possible in the minimum time, the virus does not encrypt the entire file, but only its initial part in the amount of 154 kb. Ooss virus encrypts files sequentially, when all files in the directory are encrypted, it places a new file in it. This file is called ‘_readme.txt’ and its contents are shown below.

This file is a ransom note that is a message from Ooss creators. In this message, the criminals report that the victim’s files are encrypted and there is only one way to decrypt them – buy the key and the decryptor from them. Attackers set the price for the key and decryptor at $980. If the victim pays the ransom within 72 hours, then Ooss authors agree to make a discount of half the ransom, that is, reduce the size of the ransom to $490. Criminals offer to decrypt one file for free. To do this, the victim needs to send this file to one of the email addresses listed in the ransom demand message. But successful decryption of one file does not guarantee the possibility of decryption of files even after payment of the ransom.

Threat Summary

Name	Ooss
Type	Crypto virus, Crypto malware, File locker, Ransomware, Filecoder
Encrypted files extension	.ooss
Ransom note	_readme.txt
Contact	helpdatarestore@firemail.cc, helpmanager@mail.ch
Ransom amount	$980/$490 in Bitcoins
Detection Names	Generic.mg.c830838b0f7ac303, Win32/Kryptik.HBDS, Trojan.MalPack.GS, Trojan:Win32/Wacatac.D!ml, UDS:DangerousObject.Multi.Generic, HEUR/QVM10.1.459D.Malware.Gen, MALWARERANSOM, Gen:NN.ZexaF.34090.RKW@aaUqlTcG
Symptoms	Unable to open documents, photos and music. Your documents, photos and music have new extension appended at the end of the file name. Files called like ‘_readme.txt’, ‘READ-ME’, ‘_open me’, _DECRYPT YOUR FILES’ or ‘_Your files have been encrypted” in every folder with an encrypted file. Ransom note in a pop-up window with cybercriminal’s ransom demand and instructions.
Distribution ways	Phishing emails that contain malicious attachments. Drive-by downloads (crypto malware has the ability to infect the PC system simply by visiting a web-page that is running harmful code). Social media posts (they can be used to trick users to download malicious software with a built-in ransomware downloader or click a malicious link). Remote desktop protocol (RDP) hacking.
Removal	To remove Ooss ransomware use the Ooss virus removal guide
Decryption	free STOP (Ooss) decryptor

 

In the ransom note, the authors of Ooss virus report that it is impossible to decrypt files without a key and a decryptor. In general, this is true; to decrypt .ooss files, you must use the key and the decryptor. This is confirmed by the security researchers.

As we reported at the very beginning of this article, there is a free decryptor, which in some cases can decrypt .ooss files. In the case when it could not decrypt the files, there are several more methods, each of which can help the victim restore the files encrypted by Ooss virus. These methods do not require the use of a key and decryptor, and therefore are suitable for all victims.

How to remove Ooss virus, Recover, Decrypt .ooss files for free

If you are a victim of ransomware, your files have been encrypted, then we recommend that you follow the simple steps described above. These steps will help you remove Ooss virus, and decrypt .ooss files that were affected by it. Moreover, we will also show you how to recover encrypted files if the decryption of the files was unsuccessful. Read the entire manual carefully. To make it easier for you to follow the instructions, we recommend that you print it or open it on your smartphone.

1. How to remove Ooss ransomware virus
2. How to decrypt .ooss files
3. How to restore .ooss files
4. How to protect your computer from Ooss ransomware virus

How to remove Ooss ransomware virus

The first thing you need to do before decrypting .ooss files is to make sure that Ooss virus is no longer active, as well as find all its components and remove them. An active ransomware is very dangerous because it can encrypt all files that were recovered during decryption. Therefore, you need to check your computer for ransomware and other malware. To do this, we recommend using free malware removal tools that will find Ooss virus and remove it for free.

Remove Ooss ransomware virus with Zemana Anti-Malware

Zemana can find all kinds of malware, including ransomware, as well as a variety of Trojans, viruses and rootkits. After the detection of the Ooss crypto malware, you can easily and quickly remove it.

Visit the following page to download the latest version of Zemana Anti Malware for MS Windows. Save it directly to your Windows Desktop.

After the downloading process is finished, run it and follow the prompts. Once installed, the Zemana Free will try to update itself and when this procedure is done, click the “Scan” button . Zemana utility will start scanning the whole computer to find out Ooss ransomware, other malicious software, worms and trojans.

A scan may take anywhere from 10 to 30 minutes, depending on the count of files on your computer and the speed of your computer. While the Zemana Free tool is scanning, you can see number of objects it has identified as being infected by malware. When you are ready, press “Next” button.

The Zemana Free will delete Ooss crypto malware, other kinds of potential threats such as malware and trojans.

Remove Ooss virus with MalwareBytes Anti Malware (MBAM)

If you are having issues with the Ooss ransomware virus removal, then download MalwareBytes AntiMalware. It’s free for home use, and detects and removes various malicious software that attacks your PC or degrades the system performance. MalwareBytes Anti-Malware (MBAM) can remove adware, PUPs as well as malware, including ransomware and trojans.

MalwareBytes Anti Malware can be downloaded from the following link. Save it on your Microsoft Windows desktop.

Once downloading is finished, run it and follow the prompts. Once installed, the MalwareBytes Free will try to update itself and when this process is done, press the “Scan Now” button . MalwareBytes program will scan through the whole machine for the Ooss ransomware virus, other kinds of potential threats such as malicious software and trojans. While the tool is scanning, you can see how many objects and files has already scanned. Review the scan results and then click “Quarantine Selected” button.

The MalwareBytes is a free application that you can use to delete all detected folders, files, services, registry entries and so on. To learn more about this malicious software removal utility, we recommend you to read and follow the few simple steps or the video guide below.

Use Kaspersky virus removal tool to remove Ooss ransomware virus

Kaspersky virus removal tool (KVRT) is a free removal tool that can check your PC for a wide range of security threats such as ransomware, adware, spyware, potentially unwanted applications, trojans, worms as well as other malicious software. It will perform a deep scan of the PC including hard drives and Microsoft Windows registry. When malware is found, it will help you to remove all detected threats from your PC system with a simple click.

Download Kaspersky virus removal tool (KVRT) by clicking on the following link.

Once the download is finished, double-click on the KVRT icon. Once initialization process is done, you will see the Kaspersky virus removal tool screen as on the image below.

Click Change Parameters and set a check near all your drives. Press OK to close the Parameters window. Next click Start scan button to look for Ooss ransomware virus .

When the scanning is finished, it will open the Scan Results like the one below.

Once you’ve selected what you wish to delete from your machine click on Continue to start a cleaning task.

How to decrypt .ooss files

To decrypt .ooss files, you need to use a unique key and decryptor. Security researchers confirm that it is impossible to access the contents of encrypted files without decryption. Renaming the affected files, changing their extension cannot help the victim, the files will still remain encrypted. Fortunately, Emsisoft created a free decryptor, which in some cases can decrypt .ooss files.

To decrypt .ooss files, use free STOP (Ooss) decryptor

• Download STOP (Ooss) decryptor from the following link.
  STOP Djvu decryptor
• Scroll down to ‘New Djvu ransomware’ section.
• Click the download link and save the decrypt_STOPDjvu.exe file to your desktop.
• Run decrypt_STOPDjvu.exe, read the license terms and instructions.
• On the ‘Decryptor’ tab, using the ‘Add a folder’ button, add the directory or disk where the encrypted files are located.
• Click the ‘Decrypt’ button.

As we have said several times, this decryptor can decrypt files only in some cases, when the files were encrypted with an ‘offline key’. If the files were encrypted with an ‘online key’, then they cannot be decrypted. The reason for this is that the decryption key is in the hands of criminals and this key can not be determined. But even in this case, there is a chance to restore the contents of encrypted files, we will talk about this in section “How to restore .ooss files” of this article.

How to find out which key was used to encrypt files

Since STOP (Ooss) decryptor only decrypts files encrypted with the offline key, each Ooss’s victim needs to find out which key was used to encrypt the files. Determining the type of key used is not difficult. Below we give two ways. Use any of them.

Find out the type of key using ‘_readme.txt’ file

• Open the ransom demand message (‘_readme.txt’ file).
• Scroll down to the end of the file.
• There you will see a line with the text ‘Your personal ID’.
• Below is a line of characters that starts with ‘0208’ – this is your personal id.

Find out the type of key using ‘PersonalID.txt’ file

• Open disk C.
• Open directory ‘SystemID’.
• Open file named ‘PersonalID.txt’. This file lists ‘Personal ID’s that match the keys that the virus used to encrypt files.

The ‘Personal ID’ is not a key, it is an identifier related to a key that was used to encrypt files. If the ID ends with ‘t1’, then the files are encrypted with an offline key. If the ID does not end with ‘t1’, Ooss virus used an online key. If you could not figure out how to determine which key was used to encrypt files, then we can help. Just write a request here or in the comments below.

What to do if STOP (Ooss) decryptor says “No key for New Variant offline ID”

If during decryption of .ooss files the decryptor reports No key for New Variant offline ID, then this means the following: your files are encrypted with an ‘offline key’, but the key itself has not yet been found by security researchers, in this case, you need to be patient and wait a while, in addition, you can also use alternative ways for recovering encrypted data. It is impossible to say exactly when the ‘offline key’ will be determined. Sometimes it takes several days, sometimes more. We recommend that you try to decrypt .ooss files from time to time. You can also use alternative ways listed below for recovering encrypted data.

What to do if STOP (Ooss) decryptor says “No key for New Variant online ID”

If, when you try to decrypt .ooss files, the decryptor reports No key for New Variant online ID, then this means that your files are encrypted with an ‘online key’ and their decryption is impossible, since only the Ooss authors have the key necessary for decryption. In this case, you need to use alternative methods listed below to restore the contents of encrypted files.

How to restore .ooss files

If the STOP (Ooss) decryptor did not help you, or your files are encrypted using an online key, then there is no need to panic! There are several other alternative methods that may allow you to restore the contents of encrypted files. Once again, remember to be sure to check your computer for ransomware and malware using free malware removal tools. You must be sure that Ooss virus is completely removed.

Recover .ooss files with ShadowExplorer

First of all, try to recover .ooss files from Shadow Volume Copies, which are automatically created by Windows OS. In order to recover photos, documents and music encrypted by Ooss virus from Shadow Volume Copies you can use a tool called ShadowExplorer. We recommend using this free utility because it is small in size, has a simple interface and does not require installation on a computer. Unfortunately, ransomware often removes all Shadow copies. Therefore, if Shadow Explorer cannot help you, then immediately proceed to the second method, which is given below.

Please go to the following link to download ShadowExplorer. Save it on your Windows desktop or in any other place.

After downloading is done, extract the downloaded file to a folder on your machine. This will create the necessary files as shown below.

Start the ShadowExplorerPortable program. Now select the date (2) that you want to recover from and the drive (1) you wish to recover files (folders) from as shown in the following example.

On right panel navigate to the file (folder) you want to recover. Right-click to the file or folder and click the Export button as displayed in the figure below.

And finally, specify a directory (your Desktop) to save the shadow copy of encrypted file and press ‘OK’ button.

Run PhotoRec to restore .ooss files

Another alternative way to recover .ooss files is to use data recovery software. This method requires a lot of time, but in most cases it allows you to recover part, and sometimes all, encrypted files. To restore .ooss files, use a free tool called Photo Rec. It has a simple interface and does not require installation.

Download PhotoRec on your PC system by clicking on the link below.

Once the download is finished, open a directory in which you saved it. Right click to testdisk-7.0.win and select Extract all. Follow the prompts. Next please open the testdisk-7.0 folder like below.

Double click on qphotorec_win to run PhotoRec for Windows. It’ll open a screen as on the image below.

Choose a drive to recover like below.

You will see a list of available partitions. Choose a partition that holds encrypted documents, photos and music as shown in the following example.

Click File Formats button and choose file types to restore. You can to enable or disable the recovery of certain file types. When this is finished, press OK button.

Next, click Browse button to select where restored files should be written, then click Search.

Count of recovered files is updated in real time. All recovered photos, documents and music are written in a folder that you have selected on the previous step. You can to access the files even if the restore process is not finished.

When the restore is done, press on Quit button. Next, open the directory where restored documents, photos and music are stored. You will see a contents similar to the one below.

All restored files are written in recup_dir.1, recup_dir.2 … sub-directories. If you’re looking for a specific file, then you can to sort your recovered files by extension and/or date/time.

How to protect your computer from Ooss ransomware virus

Most antivirus applications already have built-in protection system against the crypto virus. Therefore, if your system does not have an antivirus program, make sure you install it. As an extra protection, use the HitmanPro.Alert. HitmanPro.Alert is a small security utility. It can check the system integrity and alerts you when critical system functions are affected by malware. HitmanPro.Alert can detect, remove, and reverse ransomware effects.

Visit the page linked below to download the latest version of HitmanPro.Alert for MS Windows. Save it on your Microsoft Windows desktop or in any other place.

When downloading is done, open the file location. You will see an icon like below.

Double click the HitmanPro.Alert desktop icon. When the tool is started, you will be shown a window where you can select a level of protection, as displayed in the figure below.

Now click the Install button to activate the protection.

Finish words

This guide was created to help all victims of Ooss ransomware virus. We tried to give answers to the following questions: how to remove ransomware; how to decrypt .ooss files; how to recover files, if STOP (Ooss) decryptor does not help; what is an online key and what is an offline key. We hope that the information presented in this manual has helped you.

If you have questions, then write to us, leaving a comment below. If you need more help with Ooss related issues, go to here.