ALIASES:

Virus:Win32/Rungbu.A (Microsoft); W32/Rungbu (McAfee); W32.Dizan.D (Symantec); Worm.Win32.VB.du (Kaspersky); Virus.Win32.Rungbu.gen (v) (Sunbelt); Worm/VB.ZS (AVG)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 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: 46,592 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 08 May 2013

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:

  • %System Root%\Recycled

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Autostart Technique

This Trojan modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = ","

(Note: The default value data of the said registry entry is %Windows%\system32\userinit.exe,.)

Other System Modifications

This Trojan deletes the following files:

  • {malware path and file name}`.!!!

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_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "Explorer.exe "

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
*
QuickTip = "prop:Type;Size"

(Note: The default value data of the said registry entry is prop:Type;Size;Write.)

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
*
TileInfo = "prop:Type;Size"

(Note: The default value data of the said registry entry is prop:Type;Size.)

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
*
InfoTip = "prop:Type;Write;Size"

(Note: The default value data of the said registry entry is prop:Type;DocAuthor;DocTitle;DocSubject;DocComments;Write;Size.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\HideFileExt
UncheckedValue = "1"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\HideFileExt
CheckedValue = "1"

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

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

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\SuperHidden
CheckedValue = "0"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced\Folder\SuperHidden
UncheckedValue = "0"

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

It deletes the following registry keys:

HKEY_CLASSES_ROOT\scrfile\shell\
config\command

HKEY_CLASSES_ROOT\scrfile\shell\
config

HKEY_CLASSES_ROOT\scrfile\shell\
install\command

HKEY_CLASSES_ROOT\scrfile\shell\
install

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.300

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

Identify and delete files detected as PE_RUNGBU.A-O using either the Startup Disk or Recovery Console

[ 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_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 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 NT\CurrentVersion\Winlogon
    • Shell = "Explorer.exe "
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • ShowSuperHidden = "0"

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_LOCAL_MACHINE\SOFTWARE\Classes\*
    • From: QuickTip = "prop:Type;Size"
      To: QuickTip = ""prop:Type;Size;Write""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\*
    • From: TileInfo = "prop:Type;Size"
      To: TileInfo = ""prop:Type;Size""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\*
    • From: InfoTip = "prop:Type;Write;Size"
      To: InfoTip = ""prop:Type;DocAuthor;DocTitle;DocSubject;DocComments;Write;Size""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\HideFileExt
    • UncheckedValue = "1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\HideFileExt
    • From: CheckedValue = "1"
      To: CheckedValue = ""1""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: HideFileExt = "1"
      To: HideFileExt = ""1""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\SuperHidden
    • CheckedValue = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Advanced\Folder\SuperHidden
    • From: UncheckedValue = "0"
      To: UncheckedValue = ""1""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Userinit = ","
      To: Userinit = ""%Windows%\system32\userinit.exe,""

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.
  • %System Root%\Recycled

Step 7

Scan your computer with your Trend Micro product to delete files detected as PE_RUNGBU.A-O. 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.

  • {malware path and file name}`.!!!

Step 9

Restore these deleted registry keys/values from backup

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

  • In HKEY_CLASSES_ROOT\scrfile\shell\config
    • command
  • In HKEY_CLASSES_ROOT\scrfile\shell
    • config
  • In HKEY_CLASSES_ROOT\scrfile\shell\install
    • command
  • In HKEY_CLASSES_ROOT\scrfile\shell
    • install


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