WORM_OTORUN.EX
Net-Worm.Win32.Kolab.anen (Kaspersky); Backdoor:Win32/IRCbot.gen!K (Microsoft); W32.IRCBot.Gen (Symantec)
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Worm
Destructiveness: No
Encrypted: No
In the wild: Yes
OVERVIEW
This worm arrives by connecting affected removable drives to a system. It arrives via removable drives.
It drops copies of itself into all the removable drives connected to an affected system. It drops an AUTORUN.INF file to automatically execute the copies it drops when a user accesses the drives of an affected system.
TECHNICAL DETAILS
50,703 bytes
EXE
No
21 Sep 2011
Arrival Details
This worm arrives by connecting affected removable drives to a system.
It arrives via removable drives.
Installation
This worm drops the following copies of itself into the affected system:
- %System%\smsc.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.)
Autostart Technique
This worm registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\PrtSmanm
ImagePath = %System%\smsc.exe
Other System Modifications
This worm adds the following registry keys:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\PrtSmanm
It adds the following registry entries as part of its installation routine:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Shell Extensions
systemdates = {malware path and file name}
It modifies the following registry key(s)/entry(ies) as part of its installation routine:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile
EnableFirewall = 0
(Note: The default value data of the said registry entry is 1.)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wscsvc
Start = 4
(Note: The default value data of the said registry entry is 2.)
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wuauserv
Start = 4
(Note: The default value data of the said registry entry is 2.)
Propagation
This worm creates the following folders in all removable drives:
- RECYCLER\S-1-5-21-2214276341-3544434524-6043330-4321
It drops copies of itself into all the removable drives connected to an affected system.
It drops the following copy(ies) of itself in all removable drives:
- {drive}:\RECYCLER\S-1-5-21-2214276341-3544434524-6043330-4321\update.exe
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=RECYCLER\S-1-5-21-2214276341-3544434524-6043330-4321\update.exe
action=
shell\open\command=RECYCLER\S-1-5-21-2214276341-3544434524-6043330-4321\update.exe
shell\open\default=1
shell\explore\Command=RECYCLER\S-1-5-21-2214276341-3544434524-6043330-4321\update.exe
SOLUTION
9.200
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
Restart in Safe Mode
Step 3
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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Shell Extensions
- systemdates = {malware path and file name}
- systemdates = {malware path and file name}
Step 4
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\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile
- From: EnableFirewall = 0
To: EnableFirewall = 1
- From: EnableFirewall = 0
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\wscsvc
- From: Start = 4
To: Start = 2
- From: Start = 4
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\wuauserv
- From: Start = 4
To: Start = 2
- From: Start = 4
Step 5
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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
- PrtSmanm
- PrtSmanm
Step 6
Search and delete AUTORUN.INF files created by WORM_OTORUN.EX that contain these strings
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_OTORUN.EX. 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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