WORM_RONTOKBR.AK
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)
Windows 2000, Windows XP, Windows Server 2003

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
290,816 bytes
EXE
Yes
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
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
Step 3
Enable Registry Editor, Task Manager, and Folder options
Step 4
Delete this registry key
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
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
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""
- From: AlternateShell = "%System%\drivers\intel.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\AeDebug
- From: Auto = "1"
To: Auto = ""0""
- From: Auto = "1"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- From: HideFileExt = "[REG_NONE, size: 4 bytes]"
To: HideFileExt = ""1""
- From: HideFileExt = "[REG_NONE, size: 4 bytes]"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- From: Hidden = "[REG_NONE, size: 4 bytes]"
To: Hidden = ""2""
- From: Hidden = "[REG_NONE, size: 4 bytes]"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
- From: shell = "Explorer.exe %Windows%\csrss.exe"
To: shell = ""Explorer.exe""
- From: shell = "Explorer.exe %Windows%\csrss.exe"
Step 7
Search and delete these components
- %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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