TROJ_REFROS.SMUJ
Backdoor:Win32/Bifrose.AE (Microsoft); Trojan.Gen (Symantec); Trojan-Spy.Win32.Zbot.bhfu (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt)
Windows 2000, Windows XP, Windows Server 2003
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
149,867 bytes
EXE
Yes
09 Nov 2011
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 drops the following copies of itself into the affected system:
- %System%\Win32\Win32.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
It creates the following folders:
- %System%\Win32
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
Autostart Technique
This Trojan adds the following registry entries to enable its automatic execution at every system startup:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{35F5436C-D1C7-2E0B-ACBD-D83D2600C47A}
stubpath = "%System%\Win32\Win32.exe s"
Other System Modifications
This Trojan deletes the following files:
- %System%\Win32\Win32.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
It adds the following registry keys:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Active Setup\Installed Components\{35F5436C-D1C7-2E0B-ACBD-D83D2600C47A}
HKEY_LOCAL_MACHINE\SOFTWARE\Yahoo
HKEY_CURRENT_USER\SOFTWARE\Yahoo
It adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Yahoo
nck = {random values}
HKEY_CURRENT_USER\Software\Yahoo
klg = {random values}
HKEY_CURRENT_USER\Software\Yahoo
plg1 = {random values}
Dropping Routine
This Trojan drops the following files:
- %User Profile%\Application Data\addons.dat
(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.)
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
Restart in Safe Mode
Step 3
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\Active Setup\Installed Components
- {35F5436C-D1C7-2E0B-ACBD-D83D2600C47A}
- In HKEY_LOCAL_MACHINE\SOFTWARE
- Yahoo
- In HKEY_CURRENT_USER\SOFTWARE
- Yahoo
Step 4
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\Active Setup\Installed Components\{35F5436C-D1C7-2E0B-ACBD-D83D2600C47A}
- stubpath="%System%\Win32\Win32.exe s"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Yahoo
- nck={random values}
- In HKEY_CURRENT_USER\Software\Yahoo
- klg={random values}
- In HKEY_CURRENT_USER\Software\Yahoo
- plg1={random values}
Step 5
Search and delete this folder
Step 6
Search and delete this file
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_REFROS.SMUJ. 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. %System%\Win32\Win32.exe
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