ALIASES:

Trojan:Win32/CryptInject.AP!MTB (Microsoft); Trojan-FRNA!1CC8DF75FACE (McAfee); Trojan.Win32.Fsysna.ftek (Kaspersky); Mal/GandCrab-G (Sophos); Trojan.Win32.Generic!BT (Sunbelt)

 PLATFORM:

Windows

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Trojan 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: 1,699,840 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 12 Nov 2019

Arrival Details

This Trojan 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 Trojan adds the following processes:

  • "{malware file path and name}"

It creates the following folders:

  • %User Temp%\6893A5D897
  • %All Users Profile%\Windows

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit). )

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
Client Server Runtime Subsystem = "%All Users Profile%\Windows\csrss.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\System32\
Configuration

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
System32\Configuration
xi = "2834C338E6F480BEF778"

HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\
System32\Configuration
xVersion = "4.0.0.1"

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\6893A5D897\state
  • %User Temp%\6893A5D897\lock
  • %User Temp%\6893A5D897\unverified-microdesc-consensus
  • %All Users Profile%\Windows\csrss.exe

(Note: %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local\Temp on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).. %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit). )

Other Details

This Trojan connects to the following possibly malicious URL:

  • {BLOCKED}21.38
  • {BLOCKED}.223.34
  • {BLOCKED}9.206.212
  • {BLOCKED}.244.244
  • {BLOCKED}.193.9
  • {BLOCKED}.32.5
  • {BLOCKED}.0.39

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.850

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn More ]

Step 3

Identify and terminate files detected as Trojan.Win32.SMOKELOAD.SMC.hp

[ Learn More ]
  1. 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.

Step 4

Delete this registry key

[ 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_LOCAL_MACHINE\SOFTWARE\System32
    • Configuration

Step 5

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
    • Client Server Runtime Subsystem = "%All Users Profile%\Windows\csrss.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\System32\Configuration
    • xi = "2834C338E6F480BEF778"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\System32\Configuration
    • xVersion = "4.0.0.1"

Step 6

Search and delete these components

[ Learn More ]
There may be some components that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %User Temp%\6893A5D897\state
  • %User Temp%\6893A5D897\lock
  • %User Temp%\6893A5D897\unverified-microdesc-consensus
  • %All Users Profile%\Windows\csrss.exe

Step 7

Search and delete these folders

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %User Temp%\6893A5D897
  • %All Users Profile%\Windows

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Trojan.Win32.SMOKELOAD.SMC.hp. 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 this Knowledge Base page for more information.


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