A new ransomware was discovered this week by MalwareHunterTeam called Zenis Ransomware. While it is currently unknown how Zenis is being distributed, multiple victims have already become infected with this ransomware. What is most disturbing about Zenis is that it not encrypts your files, but also purposely deletes your backups.

When MalwareHunterTeam found the first sample, it was utilizing a custom encryption method when encrypting files. The latest version, and the one we will discuss in this article, utilizes AES encryption to encrypt the files.

Update: A way has been discovered to decrypt the Zenis Ransomware. If you are infected with this ransomware, please open a request for help in the Zenis Ransomware help & support topic.

Below is a brief decryption of how the Zenis ransomware encrypts a computer compiled from analysis by MalwareHunterTeam, Michael, and myself.

How Zenis Ransomware encrypts a computer

As previously stated, we do not know how the Zenis Ransomware is currently being distributed. Based on the elusiveness of the ransomware samples and comments from infected people, it could be distributed via hacked Remote Desktop services.

When executed, the current Zenis Ransomware variant will perform two checks to see if it should begin encrypting the comptuer. The first check is to see if the file that executed is named iis_agent32.exe, with this check being case insensitive. The other check is to see if a registry value exists called HKEY_CURRENT_USER\SOFTWARE\ZenisService "Active".

If the registry value exists or the file is not named iis_agent32.exe, it will terminate the process and not encrypt the computer.

Start Checks
Start Checks

If it passes the checks, it will then begin to get the ransom note ready by filling in some information, such as emails and encrypted data.

Setup Ransom Note
Setup Ransom Note

After that is completed it will execute the following commands to delete the shadow volume copies, disable startup repair, and clear event logs.

cmd.exe /C vssadmin.exe delete shadows /all /Quiet
cmd.exe /C WMIC.exe shadowcopy delete 
cmd.exe /C Bcdedit.exe /set {default} recoveryenabled no 
cmd.exe /C Bcdedit.exe /set {default} bootstatuspolicy ignoreallfailures 
cmd.exe /C wevtutil.exe cl Application 
cmd.exe /C wevtutil.exe cl Security 
cmd.exe /C wevtutil.exe cl System"

Zenis will then search for various processes and terminate them. The processes terminated are:

sql
taskmgr
regedit
backup

Now that it has prepared the system to its liking, it will begin encrypting the files on the computer. It does this by scanning the drives on the computer for files with certain extensions. If it finds a file that matches one of the following extensions, it will encrypt it using a different AES key for each file.

.txt, .doc, .docx, .xls, .xlsx, .ppt, .pptx, .odt, .jpeg, .png, .csv, .sql, .mdb, .sln, .php, .asp, .aspx, .html, .xml, .psd, .sql, .mp4, .7z, .rar, .m4a, .wma, .avi, .wmv, .csv, .d3dbsp, .zip, .sie, .sum, .ibank, .t13, .t12, .qdf, .gdb, .tax, .pkpass, .bc6, .bc7, .bkp, .qic, .bkf, .sidn, .sidd, .mddata, .itl, .itdb, .icxs, .hvpl, .hplg, .hkdb, .mdbackup, .syncdb, .gho, .cas, .svg, .map, .wmo, .itm, .sb, .fos, .mov, .vdf, .ztmp, .sis, .sid, .ncf, .menu, .layout, .dmp, .blob, .esm, .vcf, .vtf, .dazip, .fpk, .mlx, .kf, .iwd, .vpk, .tor, .psk, .rim, .w3x, .fsh, .ntl, .arch00, .lvl, .snx, .cfr, .ff, .vpp_pc, .lrf, .m2, .mcmeta, .vfs0, .mpqge, .kdb, .db0, .dba, .rofl, .hkx, .bar, .upk, .das, .iwi, .litemod, .asset, .forge, .ltx, .bsa, .apk, .re4, .sav, .lbf, .slm, .bik, .epk, .rgss3a, .pak, .big, wallet, .wotreplay, .xxx, .desc, .py, .m3u, .flv, .js, .css, .rb, .p7c, .pk7, .p7b, .p12, .pfx, .pem, .crt, .cer, .der, .x3f, .srw, .pef, .ptx, .r3d, .rw2, .rwl, .raw, .raf, .orf, .nrw, .mrwref, .mef, .erf, .kdc, .dcr, .cr2, .crw, .bay, .sr2, .srf, .arw, .3fr, .dng, .jpe, .jpg, .cdr, .indd, .ai, .eps, .pdf, .pdd, .dbf, .mdf, .wb2, .rtf, .wpd, .dxg, .xf, .dwg, .pst, .accdb, .mdb, .pptm, .pptx, .ppt, .xlk, .xlsb, .xlsm, .xlsx, .xls, .wps, .docm, .docx, .doc, .odb, .odc, .odm, .odp, .ods, .odt

When encrypting a file it will change the file name to the following format. Zenis-[2 random chars].[12 random chars]. For example, test.jpg would be encrypted and renamed to something like Zenis-4Q.4QDV9txVRGh4.  The original file name and the AES key use to encrypt the file will be encrypted and saved to end of the file.

Zenis Encrypted Files
Zenis Encrypted Files

When looking for files to encrypt, if it finds files associated with backup files, it will overwrite them three times and then delete them. This is to make it more difficult for the victim to restore files from a backup.

Delete Backup Files
Delete Backup Files

The list of extensions targeted for deletion are:

.win, .wbb, .w01, .v2i, .trn, .tibkp, .sqb, .rbk, .qic, .old, .obk, .ful, .bup, .bkup, .bkp, .bkf, .bff, .bak, .bak2, .bak3, .edb, .stm

While encrypting, it will also create ransom notes named Zenis-Instructions.html in every file that it traverses. This ransom note contains instructions on how to contact the ransomware developer in order to get their files back. The current email addresses included in the ransom notes are TheZenis@Tutanota.com, TheZenis@MailFence.com, TheZenis@Protonmail.com, and TheZenis@Mail2Tor.com.

Zenis Ransom Note
Zenis Ransom Note

The reason they ask for the ransom note is because it contains a hidden base64 encoded string that can be decrypted using the private RSA key that only the ransomware developer has possession of. When this data is decrypted, the ransomware developer can decrypt the sample file sent to them or create a decryptor.

Ransom Note Source
Ransom Note Source

As previously said, away has been discovered to decrypt the Zenis Ransomware. If you are infected with this ransomware, please open a request for help in the Zenis Ransomware help & support topic.

How to protect yourself from the Zenis Ransomware

In order to protect yourself from ransomware in general, it is important that you use good computing habits and security software. First and foremost, you should always have a reliable and tested backup of your data that can be restored in the case of an emergency, such as a ransomware attack.

As Zenis Ransomware may be installed via hacked Remote Desktop services, it is very important to make sure its locked down correctly. This includes making sure that no computers running remote desktop services are connected directly to the Internet. Instead place computers running remote desktop behind VPNs so that they are only accessible to those who have VPN accounts on your network.

It is also important to setup proper account lockout policies so that it makes it difficult for accounts to be brute forced over Remote Desktop Services.

You should also have security software that incorporates behavioral detections to combat ransomware and not just signature detections or heuristics.  For example, Emsisoft Anti-Malware and Malwarebytes Anti-Malware both contain behavioral detection that can prevent many, if not most, ransomware infections from encrypting a computer.

Last, but not least, make sure you practice the following security habits, which in many cases are the most important steps of all:

  • Backup, Backup, Backup!
  • Do not open attachments if you do not know who sent them.
  • Do not open attachments until you confirm that the person actually sent you them,
  • Scan attachments with tools like VirusTotal.
  • Make sure all Windows updates are installed as soon as they come out! Also make sure you update all programs, especially Java, Flash, and Adobe Reader. Older programs contain security vulnerabilities that are commonly exploited by malware distributors. Therefore it is important to keep them updated.
  • Make sure you use have some sort of security software installed that uses behavioral detections or white list technology. White listing can be a pain to train, but if your willing to stock with it, could have the biggest payoffs.
  • Use hard passwords and never reuse the same password at multiple sites.

For a complete guide on ransomware protection, you visit our How to Protect and Harden a Computer against Ransomware article.

Update 4/2/18 14:25 EST:

The Zenis Ransomware can now be cracked. If you are infected with this ransomware, please open a request for help in the Zenis Ransomware help & support topic.

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IOCs

Hashes:

SHA256: 9730e03ca9d052875895b4ad7ba7914f69009fd5fb58d324ee35d3e45f90d768

Files:

Zenis-Instructions.html

Registry Keys:

HKEY_CURRENT_USER\SOFTWARE\ZenisService "Active"

Associated Emails:

TheZenis@Tutanota.com
TheZenis@MailFence.com
TheZenis@Protonmail.com
TheZenis@Mail2Tor.com

Ransom Note Text:

*** All your files has been encrypted ***

I am ZENIS. A mischievous boy who loves cryptography, hardware and programming. My world is full of unanswered questions and puzzles half and half, and I'm coming to discover a new world. A world in digital space that you are supposed to play the role of my toys.

If you want to win in this game, you have to listen carefully to my instructions, otherwise you will be caught up in a one-step game and you will become the main loser of the story.

My instructions are simple and clear. Then follow these steps:

1. Send this file (Zenis-Instructions.html) to my email with one your encrypted file less than 2 MB to trust to the game.

2. I decrypt your file for free and send for you.

3. If you confirm the correctness of the files, verify that the files are correct via email

4. Then receive the price of decrypting files

5. After you have deposited, please send me the payment details

6. After i confirm deposit, i send you the "Zenis Decryptor" along with "Private Key" to recovery all your files.

Now you can finish the game. You won the game. congratulations.


Please submit your request to both emails:

TheZenis@Tutanota.com

TheZenis@MailFence.com

If you did not receive an email after six hours, submit your request to the following emails:

TheZenis@Protonmail.com

TheZenis@Mail2Tor.com (On the TOR network)


Warning: 3rd party and public programs, It may cause irreversible damage to your files. And your files will be lost forever.