WORM_RONTOKBR.AT
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)
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
43,520 bytes
EXE
Yes
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
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
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_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
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
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""
- From: Hidden = "0"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
- From: HideFileExt = "1"
To: HideFileExt = ""1""
- From: HideFileExt = "1"
- In HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\SafeBoot
- From: AlternateShell = "c_45372k.com"
To: AlternateShell = ""cmd.exe""
- From: AlternateShell = "c_45372k.com"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
- From: Shell = "Explorer.exe %Windows%\o4453727.exe"
To: Shell = ""Explorer.exe""
- From: Shell = "Explorer.exe %Windows%\o4453727.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,""
- From: Userinit = "%System%\userinit.exe,%Windows%\j6453722.exe"
Step 7
Search and delete these components
- %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
- %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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