WORM_RONTOKBR.AK


 ALIASES:

Worm:Win32/Voterai.A (Microsoft); W32/Rontokbro.gen@MM (McAfee); W32.SillyFDC (Symantec); Worm.Win32.AutoRun.tz (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Win32.Worm.VB.HA (FSecure)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 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.

It disables Task Manager, Registry Editor, and Folder Options.

  TECHNICAL DETAILS

File Size:

290,816 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

01 Dec 2012

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.

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
kb = "%System%\auto.txt"

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
shell = "Explorer.exe %Windows%\csrss.exe"

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

Other System Modifications

This worm adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Policies\
Explorer

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows NT\SystemRestore

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows NT\SystemRestore
DisableConfig = "[REG_NONE, size: 4 bytes]"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows NT\SystemRestore
DisableSR = "[REG_NONE, size: 4 bytes]"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows\Installer
LimitSystemRestoreCheckpointing = "[REG_NONE, size: 4 bytes]"

HKEY_LOCAL_MACHINE\SOFTWARE\Policies\
Microsoft\Windows\Installer
DisableMSI = "[REG_NONE, size: 4 bytes]"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "[REG_NONE, size: 4 bytes]"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\
Control\SafeBoot
AlternateShell = "%System%\drivers\intel.exe"

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\AeDebug
Auto = "1"

(Note: The default value data of the said registry entry is 0.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
HideFileExt = "[REG_NONE, size: 4 bytes]"

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = "[REG_NONE, size: 4 bytes]"

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

It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
Nofolderoptions = "[REG_NONE, size: 4 bytes]"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer
NoFolderOptions = "[REG_NONE, size: 4 bytes]"

Dropping Routine

This worm drops the following files:

  • %Windows%\Autorun.inf
  • %Windows%\csrss.exe
  • %System%\drivers\intel.exe
  • %System Root%\camp.exe
  • %System Root%\AUTORUN.INF

(Note: %Windows% is the Windows folder, which is usually C:\Windows.. %System% is the Windows system folder, which is usually C:\Windows\System32.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Identify and delete files detected as WORM_RONTOKBR.AK using either the Startup Disk or Recovery Console

[ Learn More ]

Step 3

Enable Registry Editor, Task Manager, and Folder options

[ Learn More ]
By doing this step, you also enable other applications/programs disabled by this malware/grayware/spyware.

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\Microsoft\Windows\CurrentVersion\Policies
    • Explorer
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT
    • SystemRestore

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • kb = "%System%\auto.txt"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\SystemRestore
    • DisableConfig = "[REG_NONE, size: 4 bytes]"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows NT\SystemRestore
    • DisableSR = "[REG_NONE, size: 4 bytes]"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Installer
    • LimitSystemRestoreCheckpointing = "[REG_NONE, size: 4 bytes]"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows\Installer
    • DisableMSI = "[REG_NONE, size: 4 bytes]"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • ShowSuperHidden = "[REG_NONE, size: 4 bytes]"

Step 6

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\SYSTEM\ControlSet001\Control\SafeBoot
    • From: AlternateShell = "%System%\drivers\intel.exe"
      To: AlternateShell = ""cmd.exe""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\AeDebug
    • From: Auto = "1"
      To: Auto = ""0""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: HideFileExt = "[REG_NONE, size: 4 bytes]"
      To: HideFileExt = ""1""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: Hidden = "[REG_NONE, size: 4 bytes]"
      To: Hidden = ""2""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: shell = "Explorer.exe %Windows%\csrss.exe"
      To: shell = ""Explorer.exe""

Step 7

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.
  • %Windows%\Autorun.inf
  • %Windows%\csrss.exe
  • %System%\drivers\intel.exe
  • %System Root%\camp.exe
  • %System Root%\AUTORUN.INF

Step 8

Scan your computer with your Trend Micro product to delete files detected as WORM_RONTOKBR.AK. 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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