WORM_RONTOKBR.AT


 ALIASES:

Worm:Win32/Brontok.DC@mm (Microsoft); W32/Rontokbro.gen@MM (McAfee); W32.Rontokbro.U@mm (Symantec); Email-Worm.Win32.Brontok.n (Kaspersky); Trojan.Win32.Generic!SB.0 (Sunbelt); MemScan:Win32.Worm.Brontok.J (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:

43,520 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

15 Oct 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.

Installation

This worm drops the following copies of itself into the affected system:

  • %System%\s7005\smss.exe
  • %Windows%\j6453722.exe
  • %System%\c_45372k.com
  • %System%\s7005\zh591580484y.exe
  • %Windows%\o4453727.exe
  • %Windows%\_default45372.pif
  • %Application Data%\dv6158040x\yesbron.com

It creates the following folders:

  • %System%\s7005
  • %System%\s7005\Spread.Mail.Bro
  • %System%\s7005\Spread.Sent.Bro
  • %Application Data%\dv6158040x
  • %Windows%\Wi16752

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.. %Windows% is the Windows folder, which is usually C:\Windows.)

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\Run
f2553Wil = "%System%\s7005\zh591580484y.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
A7323r = "%Windows%\j6453722.exe"

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%\o4453727.exe"

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe,%Windows%\j6453722.exe"

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

Other System Modifications

This worm modifies the following file(s):

  • %System%\drivers\etc\hosts

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It deletes the following files:

  • %System%\s7005\zh591580484y.exemsatr.bin

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\run

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\run

HKEY_CURRENT_USER\Software\Brontok

It adds the following registry entries:

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
Explorer\run
A7323r = "%Windows%\_default45372.pif"

HKEY_CURRENT_USER\Software\Brontok
Version = "Brontok.C[22]"

HKEY_CURRENT_USER\Software\Brontok
Developer = "JowoBot #VM Community"

HKEY_CURRENT_USER\Software\Brontok
Released = "09-03-06"

HKEY_CURRENT_USER\Software\Brontok
Message = "Look @ %System Root%\Baca Bro !!!.txt"

HKEY_CURRENT_USER\Software\Brontok
Dedicated 2 = "Spizaetus Cirrhatus"

It modifies the following registry entries:

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

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

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\SYSTEM\ControlSet001\
Control\SafeBoot
AlternateShell = "c_45372k.com"

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

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableRegistryTools = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer\run
f2553Wil = "%Application Data%\dv6158040x\yesbron.com"

Dropping Routine

This worm drops the following files:

  • %System%\s7005\winlogon.exe
  • %System%\s7005\lsass.exe
  • %Windows%\Wi16752\qm7890.exe
  • %System%\s7005\m7890.exe
  • %System Root%\Baca Bro !!!.txt
  • %System%\s7005\c.bron.tok.txt
  • %System%\s7005\smss.exe
  • %Windows%\j6453722.exe
  • %System%\c_45372k.com
  • %System%\s7005\zh591580484y.exe
  • %Windows%\o4453727.exe
  • %Windows%\_default45372.pif
  • %Application Data%\dv6158040x\yesbron.com
  • %System%\s7005\zh591580484y.exemsatr.bin
  • %System%\s7005\services.exe
  • %System%\s7005\csrss.exe
  • %Application Data%\jalak-931580415-bali.com

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

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 WORM_RONTOKBR.AT 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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies
    • System
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
    • run
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
    • run
  • In HKEY_CURRENT_USER\Software
    • Brontok

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • f2553Wil = "%System%\s7005\zh591580484y.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • A7323r = "%Windows%\j6453722.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • ShowSuperHidden = "0"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\Explorer\run
    • A7323r = "%Windows%\_default45372.pif"
  • In HKEY_CURRENT_USER\Software\Brontok
    • Version = "Brontok.C[22]"
  • In HKEY_CURRENT_USER\Software\Brontok
    • Developer = "JowoBot #VM Community"
  • In HKEY_CURRENT_USER\Software\Brontok
    • Released = "09-03-06"
  • In HKEY_CURRENT_USER\Software\Brontok
    • Message = "Look @ %System Root%\Baca Bro !!!.txt"
  • In HKEY_CURRENT_USER\Software\Brontok
    • Dedicated 2 = "Spizaetus Cirrhatus"

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_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: Hidden = "0"
      To: Hidden = ""2""
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • From: HideFileExt = "1"
      To: HideFileExt = ""1""
  • In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot
    • From: AlternateShell = "c_45372k.com"
      To: AlternateShell = ""cmd.exe""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Shell = "Explorer.exe %Windows%\o4453727.exe"
      To: Shell = ""Explorer.exe""
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Userinit = "%System%\userinit.exe,%Windows%\j6453722.exe"
      To: Userinit = ""%Windows%\system32\userinit.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.
  • %System%\s7005\winlogon.exe
  • %System%\s7005\lsass.exe
  • %Windows%\Wi16752\qm7890.exe
  • %System%\s7005\m7890.exe
  • %System Root%\Baca Bro !!!.txt
  • %System%\s7005\c.bron.tok.txt
  • %System%\s7005\smss.exe
  • %Windows%\j6453722.exe
  • %System%\c_45372k.com
  • %System%\s7005\zh591580484y.exe
  • %Windows%\o4453727.exe
  • %Windows%\_default45372.pif
  • %Application Data%\dv6158040x\yesbron.com
  • %System%\s7005\zh591580484y.exemsatr.bin
  • %System%\s7005\services.exe
  • %System%\s7005\csrss.exe
  • %Application Data%\jalak-931580415-bali.com

Step 8

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%\s7005
  • %System%\s7005\Spread.Mail.Bro
  • %System%\s7005\Spread.Sent.Bro
  • %Application Data%\dv6158040x
  • %Windows%\Wi16752

Step 9

Scan your computer with your Trend Micro product to delete files detected as WORM_RONTOKBR.AT. 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 10

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.

    • %System%\drivers\etc\hosts

Step 11

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.

  • %System%\s7005\zh591580484y.exemsatr.bin


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