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.
It deletes itself after execution.
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 files:
- %User Profile%\{random filename}.exe
- %User Profile%\userdiff.sav
- %System%\userdiff.sav
(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.. %System% is the Windows system folder, which is usually C:\Windows\System32.)
It adds the following processes:
Other System Modifications
This Trojan adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
MSConfig = "%User Profile%\{random filename}.exe \u"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
DeviceControl
DevData = "{hex value}"
It modifies the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe"
(Note: The default value data of the said registry entry is %System%\userinit.exe,.)
Other Details
This Trojan deletes itself after execution.
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 TROJ_KRYPTO.SME using either the Startup Disk or Recovery Console
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To identify and delete the malware/grayware file:
• On Windows XP and Server 2003 systems:
- Scan your computer with your Trend Micro product and then take note of the names of the malware/grayware files detected.
- Click Start>Run. In the Open input box, type secpol.msc and press Enter.
- In the left panel, double-click Local Policies>Security Options.
- In the right panel, double-click Recovery Console: Allow floppy copy and access to all drives and folders.
- Select Enabled and click OK.
- Insert the Windows Installation CD into the CD drive, then restart your computer.
- When prompted, press any key to boot from the CD.
- On the main menu, type r to go to the Recovery Console.
- Type the number that corresponds to the drive and directory that contains Windows (usually C:\WINDOWS) and press Enter.
- Type the Administrator password and press Enter.
- In the input box, type the following then press Enter:
SET AllowAllPaths = TRUE
del "{malware/grayware path and file name}" - Type exit and press Enter to restart the system normally.
• On Windows Vista and 7 systems:
- Scan your computer with your Trend Micro product and then take note of the names of the malware/grayware files detected.
- Insert your Windows Installation DVD in the DVD drive, then Press the restart button.
- When prompted, press any key to boot from the CD.
- Depending on your Windows Installation DVD, you might be required to select the installation language. Then on the Install Windows window, choose your language, locale, and keyboard layout or input method. Click Next, then click Repair your computer.
- Select Use recovery tools that can help fix problems starting Windows. Select your installation of Windows. Click Next.
- If the Startup Repair window appears, click Cancel, Yes, then Finish.
- In the System Recovery Options window, click Command Prompt.
- In the Command Prompt window, type the following then press Enter:
BootRec.exe /fixmbr
del "{malware/grayware path and file name}" - Type exit and press Enter to close the Command Prompt window.
- Click Restart to restart the system normally.
Step 3
Delete this registry value
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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
- MSConfig = %User Profile%\{random filename}.exe \u
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DeviceControl
To delete the registry value this malware created:
- Open Registry Editor. To do this, click Start>Run, type regedit in the text box provided, then press Enter.
- In the left panel of the Registry Editor window, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Run - In the right panel, locate and delete the entry:
MSConfig = %User Profile%\{random filename}.exe \u - In the left panel of the Registry Editor window, double-click the following:
HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>DeviceControl - In the right panel, locate and delete the entry:
DevData = {hex value} - Close Registry Editor.
Step 4
Restore this modified registry value
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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 NT\CurrentVersion\Winlogon
- From: Userinit = %System%\userinit.exe
To: Userinit = %System%\userinit.exe,
To restore the registry value this malware/grayware modified:
- Open Registry Editor. Click Start>Run, type REGEDIT in the text box provided, and then press Enter.
- In the left panel, double-click the following:
HKEY_LOCAL_MACHINE>SOFTWARE>Microsoft>Windows NT>CurrentVersion>Winlogon - In the right panel, locate the registry value:
Userinit = %System%\userinit.exe - Right-click on the value name and choose Modify. Change the value data of this entry to:
Userinit = %System%\userinit.exe, - Close Registry Editor.
Step 5
Search and delete these files
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There may be some files 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.
- %User Profile%\{random filename}.exe
- %User Profile%\userdiff.sav
- %System%\userdiff.sav
To delete malware/grayware files:
- Search for the following files:
- %User Profile%\{random filename}.exe
- %User Profile%\userdiff.sav
- %System%\userdiff.sav
Note: To do a search for the following files, right-click Start then click Search... or Find..., depending on the version of Windows you are running. For each file to be deleted, type its file name in the Named input box. In the Look In drop-down list, select My Computer, then press Enter. - Once located, select the file then press SHIFT+DELETE to permanently delete the file.
- Repeat the said steps for all files listed.
Step 6
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_KRYPTO.SME. 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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