Win32/Filecoder.SynAck [Threat Name] go to Threat

Win32/Filecoder.SynAck.A [Threat Variant Name]

Category trojan
Size 515024 B
Detection created Sep 20, 2017
Detection database version 16113
Short description

Win32/Filecoder.SynAck.A is a trojan that encrypts files on fixed, removable and network drives. To decrypt files the user is requested to comply with given conditions in exchange for a password/instructions.

Installation

The trojan does not create any copies of itself.

Payload information

Win32/Filecoder.SynAck.A is a trojan that encrypts files on fixed, removable and network drives.


The trojan searches local, removable and network drives for certain file types.


It avoids files which contain any of the following strings in their path:

  • %windir%

The trojan encrypts the file content.


The ECIES-SECP192R1, AES-ECB-256 encryption algorithm is used.


The extension of the encrypted files is changed to:

  • %originalfilename%.%randomstring%

A string with variable content is used instead of %randomstring% .


The trojan creates the following file:

  • %drive%\­==READ==THIS==PLEASE==%variable%.txt

It contains the following text:

SynAck FES (Files Encryption Software) Dear client, we apoligize for inconvinience with your files. So we make a business offer to order file recovery service from us. Also we will do auditing of your network FOR FREE if you order file recovery service. Some details about SynAck FES: This software uses ecies-secp192r1 algorithm to create unique pair of private and public keys for the session. Each file is encrypted with random key using aes-ecb-256 algorithm. We strongly recommend you not to use third-party decryptors because they can damage your files. But if you want to try to restore your files by yourself, make sure you have made backup copies of encrypted files. And please do not remove files with text notes, because they contain important information required for file restoring. If you want to order file recovery service, please contact our support using one of the following e-mail addresses: synack@scryptmail.com synack@countermail.com If you have not get a response in 24 hours, please do not panic and write on BitMessage (using site https://bitmsg.me/): BM-2cTp9eosgjWs8SV14kYCDzPN3HJkwYk1LQ Keep in mind that there are fake services offering decryption; do not believe them or you will lose your money. Anyway, there is one method you can use for proof: ask to decrypt some files for free. No one except us will be able to do that. !!!!! PLEASE INCLUDE THE FOLLOWING TEXT IN YOUR MESSAGE !!!! F/WQrv8DemBLcbmca2iZ+Rf1kK7/A3pgS3G5nGtomfkfiK1yGxuT/t6QKGQJshl2/78TIl9uou23As1c 7Wi+VKIpR2dBXqc9lKpdR8gNB90X9ZCu/wN6YEtxuZxraJn5zrIh/PsLpNgINKzeU8uZzm8qUadZ/SRS GJLgMoQAhcNZBeR2K13fjZJx9Bf+FgbLeiHf8sWXMF+Gi3OY/NyYOw/w3ZbRcVVcTovqkIXpnneLMUrh hWT2WeI2FYK9SyGn6W77ldhg8gaDsXUn9812XYnuVrTcTi63KQ1O33685dd2zfMBWX7YNR1IWMs3C7mR XSC4jKSU4RKQR+TJ3RV+TgRPbJXXs0MkSBX/95XmyypCV1+fzr6xAarf1vgKVesZlRhg31yMLt2dsXSL RpysGMI4cD5Z3/0sP+AcUCKev3KKIXYYxyF1G+Daot3j+tFx3d1GDIilbfLJENU/sjTG/M5z6TuMg3Jt zaewX/+f6ORn Best regards, SynAck Team. ====================================================== SynAck FES ======================================================

A string with variable content is used instead of %variable% .


To decrypt files the user is requested to comply with given conditions in exchange for a password/instructions.

Other information

The trojan quits immediately if it is run within a debugger.


The trojan terminates specific running processes.


The trojan creates and runs a new thread with its own program code within the following processes:

  • msiexec.exe

The following Registry entry is set:

  • [HKEY_CURRENT_USER\­SOFTWARE\­Microsoft\­Windows\­CurrentVersion\­Run]
    • "notepad-%year%-%month%-%day%-%hours%-%minutes%-%seconds%-%milliseconds%" = "notepad %drive%\­==READ==THIS==PLEASE==%variable%.txt"

This way the trojan ensures that the file is executed on every system start.


The following Registry entries are set:

  • [HKEY_LOCAL_MACHINE\­SOFTWARE\­Microsoft\­Windows NT\­CurrentVersion\­Winlogon]
    • "LegalNoticeCaption" = "SynAck FES"
  • [HKEY_LOCAL_MACHINE\­SOFTWARE\­Microsoft\­Windows NT\­CurrentVersion\­Winlogon]
    • "LegalNoticeText" = "Hello. Your files are encrypted. To restore files, please contact us by e-mail:synack@scryptmail.com or synack@countermail.com."

The trojan may display a dialog box with the title:

  • SynAck FES

The dialog box contains the following text:

  • Hello. Your files are encrypted. To restore files, please contact us by e-mail:synack@scryptmail.com or synack@countermail.com.

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