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 modifies the affected system's HOSTS files. This prevents users from accessing certain websites.
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.
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
SystemDLL.MICROSOFT = “{malware path}\{malware filename}”
HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows \CurrentVersion\Run
SystemDLL.MICROSOFT = “{malware path}\{malware filename}”
Other System Modifications
This worm adds the following registry entries:
HKEY_CURRENT_USER\Software\Microsoft\
Windows \CurrentVersion\Policies\
System"
DisableTaskMgr = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Windows \CurrentVersion\Explorer\
Advanced
Hidden = "0"
Propagation
This worm 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={Drive Letter}:\HDDFile.com
shellexecute={Drive Letter}:\
It uses any of the following Simple Mail Transfer Protocol (SMTP) servers:
Process Termination
This worm terminates the following processes if found running in the affected system's memory:
- anubis
- ashWebSv
- avgemc
- bdagent
- cpf
- avp
- keyscrambler
- mbam
- egui
- npfmsg
- ollydbg
- outpost
- vpcmapvmsrvc
- wireshark
HOSTS File Modification
This worm modifies the affected system's HOSTS files to prevent a user from accessing the following websites:
- www.virustotal.com
- www.bitdefender.com
- www.virusscan.jotti.org
- www.scanner.novirusthanks.org
- www.chip.de
- www.vscan.novirusthanks.org
- www.avira.de
- www.avast.com
Stolen Information
The stolen information is saved in the following file:
- %User Temp%\firefox.txt
- %User Temp%\data.txt
- %User Temp%\mess.txt
- %User Temp%\astlog.txt
- %User Temp%\mailpv.txt
- %User Temp%\RouterPassView.txt
- %User Temp%\iepv.txt
- %User Temp%\OperPassView.txt
- %User Temp%\ChromePass.txt
(Note: %User Temp% is the user's temporary folder, where it usually is C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Local\Temp on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)
NOTES:
This worm is infected with PE_SALITY.
It drops the following copy of itself on other drives aside from %SystemRoot%:
- {Drive Letter}:\HDDFile.com
It retrieves the following information from the system:
- passwords covered by asterisks on open windows
- Chrome usernames and passwords
- Dial-up usernames and passwords
- Firefox usernames and passwords
- IE usernames and passwords
- Opera usernames and passwords
- router usernames and passwords
- account details from the following email clients:
Outlook Express
Microsoft Outlook 2000
Microsoft Outlook 2002/2003/2007/2010
Windows Mail
Windows Live Mail
IncrediMail
Eudora
Netscape 6.x/7.x
Mozilla Thunderbird
Group Mail Free
Yahoo! Messenger application
MSN/Windows/Live Messenger application
Gmail Notifier application
Google Desktop
Google Talk
- passwords from the following instant messaging applications:
MSN Messenger
Windows Messenger
Windows Live Messenger
Yahoo Messenger
Google Talk
ICQ Lite 4.x/5.x/2003
AOL Instant Messenger
AIM 6.x
AIM Pro
Trillian
Trillian Astra
Miranda
GAIM/Pidgin
MySpace IM
PaltalkScene
Digsby
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
[ Learn More ]
[ back ]
To restart in Safe Mode:
• For Windows 2000 users
- Restart your computer.
- Press F8 when you see the Starting Windows bar at the bottom of the screen.
- Choose the Safe Mode option from the Windows Advanced Options menu then press Enter.
• For Windows XP users
- Restart your computer.
- Press F8 after the Power-On Self Test (POST) routine is done. If the Windows Advanced Options menu does not appear, try restarting then pressing F8 several times when the POST screen appears.
- Choose the Safe Mode option from the Windows Advanced Options menu then press Enter.
• For Windows Server 2003 users
- Restart your computer.
- Press F8 after Windows starts up. If the Windows Advanced Options menu does not appear, try restarting again and pressing F8 several times afterward.
- On the Windows Advanced Option menu, use the arrow keys to select Safe Mode then press Enter.
• For Windows Vista, Windows 7, and Windows Server 2008 users
- Restart your computer.
- Press F8 after the Power-On Self Test (POST) routine is done. If the Advanced Boot Options menu does not appear, try restarting and then pressing F8 several times after the POST screen is displayed.
- On the Advanced Boot Options menu, use the arrow keys to select the Safe Mode option, and then press Enter.
• For Windows 8, Windows 8.1, and Windows Server 2012 users
- Access the Charms bar by moving your mouse pointer to the upper right corner of the screen.
- Move your mouse pointer down and click Settings>Change your PC Settings.
- In the left panel, click General.
- In the right panel, scroll down to the bottom to find the Advanced startup section, then click the Restart now button and wait for the system to restart.
- In the Advanced Startup menu, click Troubleshoot>Advanced Options>Startup Settings>Restart and wait for the system to restart.
- In the Startup Settings menu, press 4 to enable safe mode.
Step 4
Delete this registry value
[ Learn More ]
[ back ]
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
- SystemDLL.MICROSOFT = “{malware path}\{malware filename}”
- In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
- SystemDLL.MICROSOFT = “{malware path}\{malware filename}”
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\System"
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
To delete the registry value this malware created:
- Open Registry Editor. To do this:
» For Windows 2000, Windows XP, and Windows Server 2003 users, click Start>Run, type regedit in the text box provided, and then press Enter.
» For Windows Vista, Windows 7, and Windows Server 2008 users, click the Start button, type regedit in the Search input field then press Enter.
» For Windows 8, Windows 8.1, and Windows Server 2012 users, right-click on the lower left corner of the screen, click Run, type regedit in the text box provided, and then press Enter. - In the left panel of the Registry Editor window, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Run - In the right panel, locate and delete the entry:
SystemDLL.MICROSOFT = “{malware path}\{malware filename}” - In the left panel of the Registry Editor window, double-click the following:
HKEY_LOCAL_MACHINE>Software>Microsoft>Windows>CurrentVersion>Run - In the right panel, locate and delete the entry:
SystemDLL.MICROSOFT = “{malware path}\{malware filename}” - In the left panel of the Registry Editor window, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Policies>System" - In the right panel, locate and delete the entry:
DisableTaskMgr = "1" - In the left panel of the Registry Editor window, double-click the following:
HKEY_CURRENT_USER>Software>Microsoft>Windows>CurrentVersion>Explorer>Advanced - In the right panel, locate and delete the entry:
Hidden = "0" - Close Registry Editor.
Step 5
Search and delete AUTORUN.INF files created by WORM_SKYSTLR.A that contain these strings
[ Learn More ]
[ back ]
- [autorun]
- open={Drive Letter}:\HDDFile.com
- shellexecute={Drive Letter}:\
To identify and delete AUTORUN.INF files created:
For Windows 2000, Windows XP, and Windows Server 2003:
- Right-click the Start button then choose Search... or Find..., depending on the version of Windows you are running.
- In the File name* input box, type:
AUTORUN.INF - In the Look in: drop-down list, select a drive, then press Enter.
- Select the file, then open using Notepad.
- Check if the following lines are present in the file:
- [autorun]
- open={Drive Letter}:\HDDFile.com
- shellexecute={Drive Letter}:\
- If the lines are present, delete the file.
- Repeat steps 3 to 6 for the remaining AUTORUN.INF files in other remaining removable drives.
- Close Search Results.
*Note: The file name input box title varies depending on the Windows version (e.g.
Search for files or folders named or
All or part of the file name.).
For Windows Vista, Windows 7, Windows Server 2003, Windows 8, Windows 8.1, and Windows Server 2012:
- Open a Windows Explorer window.
- For Windows Vista, 7, and Server 2008 users, click Start>Computer.
- For Windows 8, 8.1, and Server 2012 users, right-click on the lower left corner of the screen, then click File Explorer.
- In the Search Computer/This PC input box, type:
AUTORUN.INF - Select the file, then open using Notepad.
- Check if the following lines are present in the file:
- [autorun]
- open={Drive Letter}:\HDDFile.com
- shellexecute={Drive Letter}:\
- If the lines are present, delete the file.
- Repeat steps 3 to 5 for the remaining AUTORUN.INF files in other remaining removable drives.
- Close Search Results.
Step 6
Search and delete this file
[ Learn More ]
[ back ]
There may be some files that are hidden. Please make sure you check the
Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
- %User Temp%\firefox.txt
- %User Temp%\data.txt
- %User Temp%\mess.txt
- %User Temp%\astlog.txt
- %User Temp%\mailpv.txt
- %User Temp%\RouterPassView.txt
- %User Temp%\iepv.txt
- %User Temp%\OperPassView.txt
- %User Temp%\ChromePass.txt
To manually delete a malware/grayware file from an affected system:
• For Windows 2000, Windows XP, and Windows Server 2003:
- Right-click Start then click Search....
- In the File name* input box, type the following:
- %User Temp%\firefox.txt
- %User Temp%\data.txt
- %User Temp%\mess.txt
- %User Temp%\astlog.txt
- %User Temp%\mailpv.txt
- %User Temp%\RouterPassView.txt
- %User Temp%\iepv.txt
- %User Temp%\OperPassView.txt
- %User Temp%\ChromePass.txt
- In the Look In drop-down list, select My Computer then press Enter.
- Once located, select the file then press SHIFT+DELETE to delete it.
*Note: The file name input box title varies depending on the Windows version (e.g. Search for files or folders named or All or part of the file name.).
• For Windows Vista, Windows 7, Windows Server 2008, Windows 8, Windows 8.1, and Windows Server 2012:
- Open a Windows Explorer window.
- For Windows Vista, 7, and Server 2008 users, click Start>Computer.
- For Windows 8, 8.1, and Server 2012 users, right-click on the lower left corner of the screen, then click File Explorer.
- In the Search Computer/This PC input box, type:
- %User Temp%\firefox.txt
- %User Temp%\data.txt
- %User Temp%\mess.txt
- %User Temp%\astlog.txt
- %User Temp%\mailpv.txt
- %User Temp%\RouterPassView.txt
- %User Temp%\iepv.txt
- %User Temp%\OperPassView.txt
- %User Temp%\ChromePass.txt
- Once located, select the file then press SHIFT+DELETE to delete it.
*Note: Read the following Microsoft page if these steps do not work on Windows 7.
Step 7
Remove these strings added by the malware/grayware/spyware in the HOSTS file
[ Learn More ]
[ back ]
- 127.0.0.1 www.virustotal.com
- 127.0.0.1 www.bitdefender.com
- 127.0.0.1 www.virusscan.jotti.org
- 127.0.0.1 www.scanner.novirusthanks.org
- 127.0.0.1 www.chip.de
- 127.0.0.1 www.vscan.novirusthanks.org
- 127.0.0.1 www.avira.de
- 127.0.0.1 www.avast.com
To edit the HOSTS file:
- Open the following file using a text editor such as Notepad:
%System%\drivers\etc\HOSTS
(Note: %System% is the Windows system folder, which is usually C:\WINNT\System32 on Windows 2000, and C:\Windows\System32 on Windows XP and later.) - Delete the following entry/ies:
- 127.0.0.1 www.virustotal.com
- 127.0.0.1 www.bitdefender.com
- 127.0.0.1 www.virusscan.jotti.org
- 127.0.0.1 www.scanner.novirusthanks.org
- 127.0.0.1 www.chip.de
- 127.0.0.1 www.vscan.novirusthanks.org
- 127.0.0.1 www.avira.de
- 127.0.0.1 www.avast.com
- Save the file and close the text editor.
Step 8
Restart in normal mode and scan your computer with your Trend Micro product for files detected as WORM_SKYSTLR.A. 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.
Did this description help? Tell us how we did.