Trojan:Win32/Sulunch(Microsoft), W32/AutoRun.RPV!worm(Fortinet), Win32/AutoRun.VB.AIX worm(Eset)
Windows 2000, Windows XP, Windows Server 2003
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.
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:
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
It creates the following folders:
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
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
Microsoft = "%System Root%\Program File\Microsoft\MicrosoftSafety.exe"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Microsoft = "%System Root%\Program File\Microsoft\MicrosoftSafety.exe"
Other System Modifications
This worm adds the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon\
SpecialAccounts\UserList
SYS_4321 = "0"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\LanmanServer\Shares
SYS_A$ = "CSCFlags=0"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\LanmanServer\Shares
SYS_C$ = "CSCFlags=0"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\LanmanServer\Shares
SYS_D$ = "CSCFlags=0"
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\LanmanServer\Shares
SYS_F$ = "CSCFlags=0"
It modifies the following registry entries:
HKEY_CLASSES_ROOT\Network\SharingHandler
(Default) = ""
(Note: The default value data of the said registry entry is ntshrui.dll.)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
HideFileExt = "1"
(Note: The default value data of the said registry entry is 0.)
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"
(Note: The default value data of the said registry entry is 1.)
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
system
shutdownwithoutlogon = "0"
(Note: The default value data of the said registry entry is 1.)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\ComputerName\ComputerName
ComputerName = "{Computer Name}-"
(Note: The default value data of the said registry entry is {Computer Name}.)
Propagation
This worm creates the following folder in all physical and removable drives:
It drops the following copy of itself in all physical and removable drives:
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:
[autorun]
open=%System Root%\COMM\COMM\svchost.exe
shell\open\command=%System Root%\COMM\COMM\svchost.exe
(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)
NOTES:
This worm closes the window targeting the malware path and opens a new window targeting the created folder, {malware path and file name}.
It also adds the following user account as local administrator:
It also shares the following directory:
This worm drops copy of itself in %Desktop% and removable drives. These dropped copies use the names of the folders located on the said drives/directory for their file names.
It then sets the attributes of the original folders to Hidden to trick the user into clicking the dropped copies.
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_COSMU.ELG
Step 3
Terminate a process file/s detected as WORM_COSMU.ELG
*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.
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.
Step 6
Search and delete these folders
Step 7
Search and delete AUTORUN.INF files created by WORM_COSMU.ELG that contain these strings
[autorun]
open=%System Root%\COMM\COMM\svchost.exe
shell\open\command=%System Root%\COMM\COMM\svchost.exe
Step 8
Scan your computer with your Trend Micro product to delete files detected as WORM_COSMU.ELG. 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.
NOTES:
To delete the user account, SYS_4321:
1. Run cmd.exe
2. Type the following command:
3. To check if the account has been removed successfully, type the following command:
SYS_4321 should not be visible in the list.