Threat Descriptions

Trojan:W32/DatCrypt

Classification

Category :

Malware

Type :

Trojan

Platform :

W32

Aliases :

Trojan:W32/DatCrypt, Gen:Trojan.Heur.mqW@vrF6mAoix, Trojan.Win32.Pincav.nms, Trojan.Xrupter (Symantec) , Generic.dx!jkx trojan (McAfee)

Summary

Trojan:W32/DatCrypt drops a DLL file that encrypts files with specific extensions on the system. The DLL then informs the user that the affected files should be decrypted with a certain "utility program", which it also attempts to download and install on the system.A malware that engages in this type of behavior is known as ransomware.

Removal

Based on the settings of your F-Secure security product, it will either move the file to the quarantine where it cannot spread or cause harm, or remove it.

A False Positive is when a file is incorrectly detected as harmful, usually because its code or behavior resembles known harmful programs. A False Positive will usually be fixed in a subsequent database update without any action needed on your part. If you wish, you may also:

  • Check for the latest database updates

    First check if your F-Secure security program is using the latest updates, then try scanning the file again.

  • Submit a sample

    After checking, if you still believe the file is incorrectly detected, you can submit a sample of it for re-analysis.

    Note: If the file was moved to quarantine, you need to collect the file from quarantine before you can submit it.

  • Exclude a file from further scanning

    If you are certain that the file is safe and want to continue using it, you can exclude it from further scanning by the F-Secure security product.

    Note: You need administrative rights to change the settings.

Technical Details

Execution

The DLL file is installed in the system32 folder with a random name. While active, the DLL searches the hard drive for files with the following extensions:

  • ppsm
  • ppsx
  • ppam
  • potm
  • potx
  • pptm
  • pptx
  • xlam
  • xlsb
  • xltm
  • xltx
  • xlsm
  • xlsx
  • dotm
  • dotx
  • docm
  • docx
  • ppt
  • xls
  • doc
  • pst
  • mdb
  • wma
  • mp3
  • png
  • jpeg
  • jpg
  • pdf

Many of these extensions are for Microsoft Office documents; the others are common media formats.Files found are encrypted. The program then displays a message when the user clicks the encrypted file, informing them the file is 'corrupted':

Download

The DLL will display a system notification message related to the supposed file corruption:

When clicked, the message initiates a download of a "utility program" for decrypting the affected files. The download is from

  • https://datahelpercorp.com/[...].exe

The downloaded utility program is detected as Rogue:W32/DatDoc.