WORM_OTORUN.ZYN
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.
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
1,415,146 bytes
EXE
Yes
17 Nov 2011
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:
- %Windows%\J_Y.exe
- %Windows%\J_Y.WoRm.Jpg
(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)
It drops the following component file(s):
- %System%\dllcache\brofnet.cm
- %System%\dllcache\cweener.xr
- %System%\dllcache\date.avi
- %System%\dllcache\mrahamX.pro
- %System%\dllcache\NET14.COM
- %System%\dllcache\nvsvc32.com
- %System%\dllcache\PLURPP.COM
- %System%\dllcache\reotspnwy16.dll
- %System%\dllcache\secux32.exe
- %System%\dllcache\SuStur32.exe
- %System%\dllcache\varnal16.ber
- %System%\dllcache\xorebro.pif
It drops the following copies of itself into the affected system:
- %Windows%\J_Y.exe
- %Windows%\J_Y.WoRm.Jpg
(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)
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
J_Y = "%Windows%\J_Y.exe"
Other System Modifications
This worm adds the following registry keys:
HKEY_CLASSES_ROOT\.cha
HKEY_CLASSES_ROOT\ChatFile
HKEY_CLASSES_ROOT\irc\Shell\
open\ddeexec
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
.cha
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
ChatFile
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SRVStarter_sys32
It modifies the following registry entries:
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "Explorer.exe J_Y.exe"
(Note: The default value data of the said registry entry is Explorer.exe.)
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
mIRC
UninstallString = ""%System%\dllcache\nvsvc32.com" -uninstall"
(Note: The default value data of the said registry entry is %Program Files%\mIRC\uninstall.exe _?=%Program Files%\mIRC.)
Propagation
This worm drops the following copies of itself in all physical and removable drives:
- J_Y.exe
- J_Y.WoRm.Jpg
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]
shellexecute=WScript //d //b //H:WScript /e:vbscript J_Y.jpg
SOLUTION
9.200
8.580.04
17 Nov 2011
8.581.00
18 Nov 2011
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
Scan your computer with your Trend Micro product and note files detected as WORM_OTORUN.ZYN
Step 3
Restart in Safe Mode
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\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
- From: Shell = "Explorer.exe J_Y.exe"
To: Shell = "Explorer.exe"
- From: Shell = "Explorer.exe J_Y.exe"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\mIRC
- From: UninstallString = ""%System%\dllcache\nvsvc32.com" -uninstall"
To: UninstallString = "%Program Files%\mIRC\uninstall.exe _?=%Program Files%\mIRC"
- From: UninstallString = ""%System%\dllcache\nvsvc32.com" -uninstall"
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_CLASSES_ROOT
- .cha
- .cha
- In HKEY_CLASSES_ROOT
- ChatFile
- ChatFile
- In HKEY_CLASSES_ROOT\irc\Shell\open
- ddeexec
- ddeexec
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes
- .cha
- .cha
- In HKEY_LOCAL_MACHINE\SOFTWARE\Classes
- ChatFile
- ChatFile
- In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
- SRVStarter_sys32
- SRVStarter_sys32
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- J_Y
- J_Y
Step 6
Search and delete this file
- %System%\dllcache\brofnet.cm
- %System%\dllcache\cweener.xr
- %System%\dllcache\date.avi
- %System%\dllcache\mrahamX.pro
- %System%\dllcache\NET14.COM
- %System%\dllcache\nvsvc32.com
- %System%\dllcache\PLURPP.COM
- %System%\dllcache\reotspnwy16.dll
- %System%\dllcache\secux32.exe
- %System%\dllcache\SuStur32.exe
- %System%\dllcache\varnal16.ber
- %System%\dllcache\xorebro.pif
Step 7
Search and delete AUTORUN.INF files created by WORM_OTORUN.ZYN that contain these strings
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_OTORUN.ZYN. 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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