Trojan.Win32.SKEEYAH.WLDC

May 04, 2020
 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:

413,696 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

04 May 2020

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:

  • %System%\svchost.exe %All Users Profile%\dh2b82b2b.exe
  • "%AppDataLocal%\ldd7E73.tmp.bat" "{malware file path and name}"
  • %AppDataLocal%\ldd7E73.tmp.bat "{malware file path and name}"

(Note: %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). . %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Local on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It creates the following folders:

  • %Application Data%\f50dca1e

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming 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
IntelPowerAgent4 = "rundll32.exe shell32.dll, ShellExec_RunDLL %All Users Profile%\DH2B82~1.EXE"

Other System Modifications

This Trojan modifies the following file(s):

  • {malware file path and name}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Windows
3492473c = "{random characters}"

Dropping Routine

This Trojan drops the following files:

  • %AppDataLocal%\ldd7E73.tmp.bat
  • %Application Data%\f50dca1e\3_info.txt
  • %Application Data%\f50dca1e\3_cert.pfx
  • {malware file path and name}
  • %Application Data%\f50dca1e\1_info.txt
  • %Application Data%\f50dca1e\2_cert.pfx
  • %All Users Profile%\dh2b82b2b.exe
  • %Application Data%\f50dca1e\cmdline.txt
  • %Application Data%\f50dca1e\2_info.txt
  • %Application Data%\f50dca1e\4_cert.pfx
  • %Application Data%\f50dca1e\1_cert.pfx
  • %Application Data%\f50dca1e\4_info.txt

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

  • http://download.{BLOCKED}supdate.com
  • http://{BLOCKED}idomen.com

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.SKEEYAH.WLDC

[ 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 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
    • IntelPowerAgent4 = "rundll32.exe shell32.dll, ShellExec_RunDLL %All Users Profile%\DH2B82~1.EXE"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows
    • 3492473c = "{random characters}"

Step 5

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.
  • %AppDataLocal%\ldd7E73.tmp.bat
  • %Application Data%\f50dca1e\3_info.txt
  • %Application Data%\f50dca1e\3_cert.pfx
  • {malware file path and name}
  • %Application Data%\f50dca1e\1_info.txt
  • %Application Data%\f50dca1e\2_cert.pfx
  • %All Users Profile%\dh2b82b2b.exe
  • %Application Data%\f50dca1e\cmdline.txt
  • %Application Data%\f50dca1e\2_info.txt
  • %Application Data%\f50dca1e\4_cert.pfx
  • %Application Data%\f50dca1e\1_cert.pfx
  • %Application Data%\f50dca1e\4_info.txt

Step 6

Search and delete this folder

[ 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.
  • %Application Data%\f50dca1e

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as Trojan.Win32.SKEEYAH.WLDC. 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.

Step 8

Restore deleted/modified files and/or registry entries from backup

*Note: Only Microsoft-related files/keys/values will be restored. If this malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

    • {malware file path and name}


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