WORM_SILLY.SMRP
Virus:Win32/Capsfin.A (MICROSOFT), W32.SillyFDC (NORTON)
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Worm
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
This worm arrives via removable drives. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
It uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.
It bypasses the Windows firewall. This allows the malware to perform its intended routine without being detected by an installed firewall.
TECHNICAL DETAILS
Arrival Details
This worm arrives via removable drives.
It 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 adds the following folders:
- %System%\inf\
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)
It drops the following copies of itself into the affected system:
- %User Profile%\gupd.exe
(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.)
It drops the following files:
- %System%\inf\svchost.exe ( detected as TROJ_COMREROP.AG )
- %Windows%\INETINFO.exe
(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.. %Windows% is the Windows folder, where it usually is C:\Windows on all Windows operating system versions.)
It uses the default Windows folder icon to trick users into opening the file. Double-clicking the file executes this malware.
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
gtalkupdate = "%User Profile%\gupd.exe"
Other System Modifications
This worm adds the following registry entries as part of its installation routine:
HKEY_CURRENT_USER\Software\Chilkat Software, Inc.\
ChilkatMail
Key30 = "{random characters}"
HKEY_LOCAL_MACHINE\SOFTWARE\Chilkat Software, Inc.\
ChilkatMail
Key30 = "{random characters}"
It adds the following registry keys as part of its installation routine:
HKEY_CURRENT_USER\Software\Chilkat Software, Inc.
HKEY_CURRENT_USER\Software\Chilkat Software, Inc.\
ChilkatMail
HKEY_LOCAL_MACHINE\SOFTWARE\Chilkat Software, Inc.
HKEY_LOCAL_MACHINE\SOFTWARE\Chilkat Software, Inc.\
ChilkatMail
It modifies the following registry entries to disable the Windows Firewall settings:
HKEY_LOCAL_MACHINE\System\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%System%\inf\svchost.exe = "%System%\inf\svchost.exe:*:Enabled:@xpsp2res.dll,-22001"
Other Details
This worm connects to the following URL(s) to check for an Internet connection:
- http://www.google.com/index.html
SOLUTION
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
Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.
Step 3
Restart in Safe Mode
Step 4
Search and delete this folder
- %System%\inf\
Step 5
Search and delete this file
- %Windows%\INETINFO.exe
Step 6
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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.
- In HKEY_CURRENT_USER\Software
- Chilkat Software, Inc.
- Chilkat Software, Inc.
- In HKEY_LOCAL_MACHINE\SOFTWARE
- Chilkat Software, Inc.
- Chilkat Software, Inc.
Step 7
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
- gtalkupdate = "%User Profile%\gupd.exe"
- gtalkupdate = "%User Profile%\gupd.exe"
- In HKEY_LOCAL_MACHINE\System\
\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
- %System%\inf\svchost.exe = "%System%\inf\svchost.exe:*:Enabled:@xpsp2res.dll,-22001"
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_SILLY.SMRP. 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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