Analysis by: John Kevin Sanchez
ALIASES:

Win32.Trojan-psw.Fakeransom.Lmua (Tencent), Hoax.Win32.FakeRansom.cm (Kaspersky)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Joke Program

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Joke Program arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

  TECHNICAL DETAILS

File Size: 402,437 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 20 Jan 2018

Arrival Details

This Joke Program arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This Joke Program drops the following copies of itself into the affected system:

  • %Desktop%\#Decryptor.exe

(Note: %Desktop% is the desktop folder, where it usually is C:\Documents and Settings\{user name}\Desktop in Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\Desktop in Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Autostart Technique

This Joke Program adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
#Decryptor = {malware filename}

NOTES:

Once executed, this joke program displays a window that prompts the user with decryption of the user's files while also asking for a ransom to save encrypted files. It does not, however, encrypt any files.

  SOLUTION

Minimum Scan Engine: 9.850
SSAPI PATTERN File: 1.913.00
SSAPI PATTERN Date: 20 Jan 2018

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Terminate this process

[ Learn More ]

  1. For Windows 98 and ME users, the Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
  2. If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
  3. If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.
DATA_GENERIC
  • Select the malware/grayware/spyware process, then press either the End Task or the End Process button, depending on the version of Windows you are using.
  • To check if the malware/grayware/spyware process has been terminated, close Task Manager, and then open it again.
  • Close Task Manager.

    • Step 4

    Delete this registry value

    [ Learn More ]

    Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

     
    • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
      • #Decryptor = {malware filename}

    Step 5

    Scan your computer with your Trend Micro product to delete files detected as JOKE_FAKERANSOM. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check the following Trend Micro Support pages for more information:


    Did this description help? Tell us how we did.