WORM_AUTORUN.IYK
Mal/SillyFDC-A(Sophos), W32/AutoRun.BSCV!worm(Fortinet), Win32.Worm.Autorun(Ikarus), a variant of Win32/Small.NCC worm(Eset)
Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

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 drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.
It deletes itself after execution.
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.
Installation
This worm drops the following copies of itself into the affected system and executes them:
- %System%\{malware file name}.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
It drops the following files:
- %System Root%\D_20866.nsl
- {malware path}\ralog.dll
- {Drive letter}:\D_20866.nsl
- {Drive letter}:\D_20876.nsl
- {Drive letter}:\D_20877.nsl
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
It drops and executes the following files:
- %System%\rar.exe
(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)
It creates the following folders:
- %Application Data%\WinRAR
- %System%\Debug
- %System%\Debug\210271704
- %System%\Debug\new
(Note: %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.. %System% is the Windows system folder, which is usually C:\Windows\System32.)
Autostart Technique
This worm adds the following registry entries to enable its automatic execution at every system startup:
HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Windows
run = "%System%\{malware file name}.exe"
Propagation
This worm creates the following folders in all removable drives:
- {Drive letter}:\System Volume Information
- {Drive letter}:\System Volume Information\com1.{20D04FE0-3AEA-1069-A2D8-08002B30309D}
It drops the following copy(ies) of itself in all removable drives:
- {Drive letter}:\New Folder .exe
- {Drive letter}:\System Volume Information\com1.{20D04FE0-3AEA-1069-A2D8-08002B30309D}\weasvc.pif
It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.
The said .INF file contains the following strings:
\Device\HarddiskVolume3\System Volume Information\_restore{29EDEB88-DF1A-4606-99B7-5C846817BE9D}\RP{incrementing digit}\_restore{29JHGB88-DF1A-4606-99B7-5CGSU17BE9D}\change.log
[Autorun]
\Device\HarddiskVolume3\System Volume Information\_restore{29EDEB88-DF1A-4606-99B7-5C846817BE9D}\RP{incrementing digit}\_restore{29JHGB88-DF1A-4606-99B7-5CGSU17BE9D}\change.log
open=
\Device\HarddiskVolume3\System Volume Information\_restore{29EDEB88-DF1A-4606-99B7-5C846817BE9D}\RP{incrementing digit}\_restore{29JHGB88-DF1A-4606-99B7-5CGSU17BE9D}\change.log
shell\open\Command=system~1\com1.{20D04FE0-3AEA-1069-A2D8-08002B30309D}\weasvc.pif
\Device\HarddiskVolume3\System Volume Information\_restore{29EDEB88-DF1A-4606-99B7-5C846817BE9D}\RP{incrementing digit}\_restore{29JHGB88-DF1A-4606-99B7-5CGSU17BE9D}\change.log
shell\open\Default=1
\Device\HarddiskVolume3\System Volume Information\_restore{29EDEB88-DF1A-4606-99B7-5C846817BE9D}\RP{incrementing digit}\_restore{29JHGB88-DF1A-4606-99B7-5CGSU17BE9D}\change.log
shell\explore\Command=system~1\com1.{20D04FE0-3AEA-1069-A2D8-08002B30309D}\weasvc.pif
\Device\HarddiskVolume3\System Volume Information\_restore{29EDEB88-DF1A-4606-99B7-5C846817BE9D}\RP{incrementing digit}\_restore{29JHGB88-DF1A-4606-99B7-5CGSU17BE9D}\change.log
Other Details
This worm deletes itself after execution.
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
Scan your computer with your Trend Micro product and note files detected as WORM_AUTORUN.IYK
Step 3
Terminate a process file/s detected as WORM_AUTORUN.IYK
*Note: If the detected file/s is/are not displayed in theWindows Task Manager, continue doing the next steps.
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 NT\CurrentVersion\Windows
- run = "%System%\{malware file name}.exe"
- run = "%System%\{malware file name}.exe"
Step 5
Search and delete these folders
- %Application Data%\WinRAR
- %System%\Debug
- {Drive letter}:\System Volume Information
Step 6
Search and delete this file
- %System%\rar.exe
- %System Root%\D_20866.nsl
- {malware path}\ralog.dll
- {Drive letter}:\D_20866.nsl
- {Drive letter}:\D_20876.nsl
- {Drive letter}:\D_20877.nsl
Step 7
Search and delete AUTORUN.INF files created by WORM_AUTORUN.IYK that contain these strings
\Device\HarddiskVolume3\System Volume Information\_restore{29EDEB88-DF1A-4606-99B7-5C846817BE9D}\RP{incrementing digit}\_restore{29JHGB88-DF1A-4606-99B7-5CGSU17BE9D}\change.log
[Autorun]
\Device\HarddiskVolume3\System Volume Information\_restore{29EDEB88-DF1A-4606-99B7-5C846817BE9D}\RP{incrementing digit}\_restore{29JHGB88-DF1A-4606-99B7-5CGSU17BE9D}\change.log
open=
\Device\HarddiskVolume3\System Volume Information\_restore{29EDEB88-DF1A-4606-99B7-5C846817BE9D}\RP{incrementing digit}\_restore{29JHGB88-DF1A-4606-99B7-5CGSU17BE9D}\change.log
shell\open\Command=system~1\com1.{20D04FE0-3AEA-1069-A2D8-08002B30309D}\weasvc.pif
\Device\HarddiskVolume3\System Volume Information\_restore{29EDEB88-DF1A-4606-99B7-5C846817BE9D}\RP{incrementing digit}\_restore{29JHGB88-DF1A-4606-99B7-5CGSU17BE9D}\change.log
shell\open\Default=1
\Device\HarddiskVolume3\System Volume Information\_restore{29EDEB88-DF1A-4606-99B7-5C846817BE9D}\RP{incrementing digit}\_restore{29JHGB88-DF1A-4606-99B7-5CGSU17BE9D}\change.log
shell\explore\Command=system~1\com1.{20D04FE0-3AEA-1069-A2D8-08002B30309D}\weasvc.pif
\Device\HarddiskVolume3\System Volume Information\_restore{29EDEB88-DF1A-4606-99B7-5C846817BE9D}\RP{incrementing digit}\_restore{29JHGB88-DF1A-4606-99B7-5CGSU17BE9D}\change.log
Step 8
Scan your computer with your Trend Micro product to delete files detected as WORM_AUTORUN.IYK. 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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