WORM_SILLY.LR
Trojan:Win32/Otran (Microsoft); Generic.dx!exx (McAfee); W32.SillyDC (Symantec); Trojan.Win32.Scar.nux, Trojan.Win32.Scar.nux (Kaspersky); ERROR (Sunbelt); Win32.Worm.VB.NXN (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.
TECHNICAL DETAILS
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 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 tcpip.exe"
(Note: The default value data of the said registry entry is Explorer.exe.)
Other System Modifications
This worm deletes the following files:
- %System%\taskmgr.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.)
It adds the following registry keys:
HKEY_CURRENT_USER\Software\Microsoft\
Windows Script\Settings
It adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows Script\Settings
JITDebug = "0"
Dropping Routine
This worm drops the following files:
- %System%\send.vbs
- %System Root%\taskmrg.exe
- %System%\db.dll
(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.. %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
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_SILLY.LR using either the Startup Disk or Recovery Console
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_CURRENT_USER\Software\Microsoft\Windows Script
- Settings
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_CURRENT_USER\Software\Microsoft\Windows Script\Settings
- JITDebug = "0"
Step 5
Restore this modified 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 NT\CurrentVersion\Winlogon
- From: Shell = "Explorer.exe tcpip.exe"
To: Shell = ""Explorer.exe""
- From: Shell = "Explorer.exe tcpip.exe"
Step 6
Search and delete these files
- %System%\send.vbs
- %System Root%\taskmrg.exe
- %System%\db.dll
Step 7
Scan your computer with your Trend Micro product to delete files detected as WORM_SILLY.LR. 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%\taskmgr.exe
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