ALIASES:

Trojan:Win32/Skeeyah.A!bit (Microsoft); RDN/Ransom (McAfee); Trojan.Gen (Symantec); Trojan-Ransom.Win32.Snocry.wi (Kaspersky); Troj/Skeeyah-K (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: 734,054 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 07 Aug 2015

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 creates the following folders:

  • %User Profile%\Application Data\gnupg

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)

Other System Modifications

This Trojan deletes the following files:

  • %User Temp%\7za.exe
  • %User Temp%\C30ADA~1.AE7
  • %System Root%/DOCUME~1/Wilbert/LOCALS~1/Temp\pubring.bak

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on 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.. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad\Options

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad\Text

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad\RTF

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad\Word6

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad\Write

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad\IP

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad\Recent File List

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets\
Wordpad\Settings

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
WBEM\WDM
%System%\advapi32.dll[MofResourceName] = "{random characters}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
WBEM\WDM
%System%\DRIVERS\ACPI.sys[ACPIMOFResource] = "{random characters}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
WBEM\WDM
%System%\DRIVERS\mssmbios.sys[MofResource] = "{random characters}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
WBEM\WDM
%System%\DRIVERS\intelppm.sys[PROCESSORWMI] = "{random characters}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
WBEM\WDM
%System%\DRIVERS\ipnat.sys[IPNATMofResource] = "{random characters}"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
WBEM\WDM
%System%\Drivers\HTTP.sys[UlMofResource] = "{random characters}"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
WBEM\PROVIDERS\Performance
Performance Refreshed = "0"

(Note: The default value data of the said registry entry is 1.)

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\rdata
  • %User Temp%\text
  • %User Temp%\document.doc
  • update.cmd
  • gpg.exe
  • %User Temp%\41e65d8f.e8ad5491
  • %User Temp%\c30ada7d.ae716421
  • %User Temp%\b528dbf1.cab3c453
  • %User Temp%\49f83a48.a766bd5e
  • %User Temp%\7fbcbc76.f180e30e
  • %User Temp%\aae53d47.vbs
  • %User Temp%\5e763ca9.js
  • %User Temp%\5387da10.cmd
  • %System Root%/DOCUME~1/Wilbert/LOCALS~1/Temp\secring.gpg
  • %System Root%/DOCUME~1/Wilbert/LOCALS~1/Temp\pubring.gpg
  • %System Root%/DOCUME~1/Wilbert/LOCALS~1/Temp\pubring.tmp
  • %System Root%/DOCUME~1/Wilbert/LOCALS~1/Temp\secring.tmp
  • %System Root%/DOCUME~1/Wilbert/LOCALS~1/Temp\trustdb.gpg
  • %System Root%/DOCUME~1/Wilbert/LOCALS~1/Temp\random_seed

(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on 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.. %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • {BLOCKED}0.1
  • {BLOCKED}.40.62

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.750

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

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets
    • Wordpad
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Wordpad
    • Options
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Wordpad
    • Text
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Wordpad
    • RTF
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Wordpad
    • Word6
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Wordpad
    • Write
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Wordpad
    • IP
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Wordpad
    • Recent File List
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Applets\Wordpad
    • Settings

Step 3

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_LOCAL_MACHINE\SOFTWARE\Microsoft\WBEM\WDM
    • %System%\advapi32.dll[MofResourceName] = "{random characters}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WBEM\WDM
    • %System%\DRIVERS\ACPI.sys[ACPIMOFResource] = "{random characters}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WBEM\WDM
    • %System%\DRIVERS\mssmbios.sys[MofResource] = "{random characters}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WBEM\WDM
    • %System%\DRIVERS\intelppm.sys[PROCESSORWMI] = "{random characters}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WBEM\WDM
    • %System%\DRIVERS\ipnat.sys[IPNATMofResource] = "{random characters}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WBEM\WDM
    • %System%\Drivers\HTTP.sys[UlMofResource] = "{random characters}"

Step 4

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WBEM\PROVIDERS\Performance
    • From: Performance Refreshed = "0"
      To: Performance Refreshed = ""1""

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.
  • %User Temp%\rdata
  • %User Temp%\text
  • %User Temp%\document.doc
  • update.cmd
  • gpg.exe
  • %User Temp%\41e65d8f.e8ad5491
  • %User Temp%\c30ada7d.ae716421
  • %User Temp%\b528dbf1.cab3c453
  • %User Temp%\49f83a48.a766bd5e
  • %User Temp%\7fbcbc76.f180e30e
  • %User Temp%\aae53d47.vbs
  • %User Temp%\5e763ca9.js
  • %User Temp%\5387da10.cmd
  • %System Root%/DOCUME~1/Wilbert/LOCALS~1/Temp\secring.gpg
  • %System Root%/DOCUME~1/Wilbert/LOCALS~1/Temp\pubring.gpg
  • %System Root%/DOCUME~1/Wilbert/LOCALS~1/Temp\pubring.tmp
  • %System Root%/DOCUME~1/Wilbert/LOCALS~1/Temp\secring.tmp
  • %System Root%/DOCUME~1/Wilbert/LOCALS~1/Temp\trustdb.gpg
  • %System Root%/DOCUME~1/Wilbert/LOCALS~1/Temp\random_seed

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.
  • %User Profile%\Application Data\gnupg

Step 7

Scan your computer with your Trend Micro product to delete files detected as TROJ_CRYPVAULT.C. 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 this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %User Temp%\7za.exe
  • %User Temp%\C30ADA~1.AE7
  • %System Root%/DOCUME~1/Wilbert/LOCALS~1/Temp\pubring.bak


Did this description help? Tell us how we did.