ALIASES:

TrojanSpy:MSIL/Golroted.B (Microsoft); Trojan.Gen.2 (Symantec); Trojan.Win32.Vimditator.gsf (Kaspersky); Troj/Malit-EX, Mal/MalitRar-B (Sophos); Trojan.Win32.Generic.pak!cobra (Sunbelt)

 PLATFORM:

Windows

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

  • Threat Type: Worm

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This worm 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: 1,281,168 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 07 Mar 2015

Arrival Details

This worm 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 worm creates the following folders:

  • %System Root%\Documents and Settings\Wilbert
  • %User Profile%\c259zy3

(Note: %System Root% is the Windows root folder, where it usually is C:\ on all Windows operating system versions.. %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.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
%User Profile%\c259zy3 = "%User Profile%\c259zy3\amgxnizu.vbs"

Other System Modifications

This worm modifies the following file(s):

  • %Application Data%\GDIPFONTCACHEV1.DAT

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.)

It adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
ESENT\Process\RegSvcs

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
ESENT\Process\RegSvcs\
DEBUG

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
GDIPlus
FontCachePath = "%Application Data%"

(Note: The default value data of the said registry entry is %User Profile%\Local Settings\Application Data.)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Eventlog\Application\
ESENT
EventMessageFile = "%System%\ESENT.dll"

(Note: The default value data of the said registry entry is {random values}.)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Eventlog\Application\
ESENT
CategoryMessageFile = "%System%\ESENT.dll"

(Note: The default value data of the said registry entry is {random values}.)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Eventlog\Application\
ESENT
CategoryCount = "1"

(Note: The default value data of the said registry entry is 10.)

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Services\Eventlog\Application\
ESENT
TypesSupported = "7"

(Note: The default value data of the said registry entry is 7.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = "1"

(Note: The default value data of the said registry entry is 2.)

Dropping Routine

This worm drops the following files:

  • __tmp_rar_sfx_access_check_33875
  • xkapmssjyn.QLM
  • xtodpqrmdcpb.exe
  • qekxbvg
  • tnedz.KCC
  • %User Profile%\Application Data\pid.txt
  • %User Profile%\Application Data\pidloc.txt

(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 Details

This worm connects to the following possibly malicious URL:

  • {BLOCKED}.248.172

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.700

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

Restart in Safe Mode

[ Learn More ]

Step 3

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\Microsoft\ESENT\Process
    • RegSvcs
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\ESENT\Process\RegSvcs
    • DEBUG

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\RunOnce
    • %User Profile%\c259zy3 = "%User Profile%\c259zy3\amgxnizu.vbs"

Step 5

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_CURRENT_USER\Software\Microsoft\GDIPlus
    • From: FontCachePath = "%Application Data%"
      To: FontCachePath = ""%User Profile%\Local Settings\Application Data""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Eventlog\Application\ESENT
    • From: EventMessageFile = "%System%\ESENT.dll"
      To: EventMessageFile = ""{random values}""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Eventlog\Application\ESENT
    • From: CategoryMessageFile = "%System%\ESENT.dll"
      To: CategoryMessageFile = ""{random values}""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Eventlog\Application\ESENT
    • From: CategoryCount = "1"
      To: CategoryCount = ""10""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Services\Eventlog\Application\ESENT
    • From: TypesSupported = "7"
      To: TypesSupported = ""7""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: Hidden = "1"
      To: Hidden = ""2""

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.
  • __tmp_rar_sfx_access_check_33875
  • xkapmssjyn.QLM
  • xtodpqrmdcpb.exe
  • qekxbvg
  • tnedz.KCC
  • %User Profile%\Application Data\pid.txt
  • %User Profile%\Application Data\pidloc.txt

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.
  • %System Root%\Documents and Settings\Wilbert
  • %User Profile%\c259zy3

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_GOLROTED.YUW. 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 9

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.

    • %Application Data%\GDIPFONTCACHEV1.DAT


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