WORM_SOHANAD.ILA

This worm arrives by connecting affected removable drives to a system. It arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It uses Windows Task Scheduler to create a scheduled task that executes the dropped copy.

It disables Task Manager, Registry Editor, and Folder Options.

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 user's Internet Explorer home page into a certain website. This action allows the malware to point to a website which may contain malware, putting the affected computer at greater risk of malware infection. It modifies the user's Internet Explorer search page into a certain website. This action allows the malware to point to a website which may contain malware, putting the affected computer at greater risk of malware infection.

Arrival Details

This worm arrives by connecting affected removable drives to a system.

It may arrive via network shares.

It 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%\gphone.exe
• %System%\gphone.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows.. %System% is the Windows system folder, which is usually C:\Windows\System32.)

It drops the following files:

• %System%\autorun.ini
• %User Temp%\log_{Time stamp}.tx

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.)

It uses Windows Task Scheduler to create a scheduled task that executes the dropped copy.

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
Yahoo Messengger = "%System%\gphone.exe"

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "Explorer.exe gphone.exe"

(Note: The default value data of the said registry entry is Explorer.exe.)

The scheduled task executes the malware at the following period:

• every day 9:00 AM

Other System Modifications

This worm adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings
GlobalUserOffline = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Schedule
AtTaskMaxHours = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
WorkgroupCrawler\Shares
shared = "\New Folder.exe"

It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableRegistryTools = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NofolderOptions = "1"

It deletes the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
IEProtection =

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
BkavFw =

Propagation

This worm searches for folders in all physical and removable drives then drops copies of itself inside the folder as {folder name}.EXE.

It drops the following copies of itself in all physical and removable drives:

• gphone.exe
• New Folder.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=gphone.exe
Shellexecute=gphone.exe
Shell\Open\command=gphone.exe
Shell=Open

It sends messages that contain links to sites hosting remote copies of itself using the following instant-messaging (IM) applications:

• Google Talk
• Yahoo! Messenger

Process Termination

This worm terminates the following processes if found running in the affected system's memory:

• [FireLion]
• Bkav2006
• cmd.exe
• game_y.exe
• Registry
• System Configuration
• Windows Task

Web Browser Home Page and Search Page Modification

This worm modifies the user's Internet Explorer home page to the following websites:

• http://{BLOCKED}.googlepages.com/google.html

It modifies the user's Internet Explorer search engine into the following websites:

• http://{BLOCKED}.googlepages.com/google.html

Dropping Routine

This worm sets the attributes of its dropped file(s) to the following:

• Hidden
• Read-Only
• System

Download Routine

This worm connects to the following URL(s) to download its component file(s):

• http://{BLOCKED}9.googlepages.com/setting.ini

It saves the files it downloads using the following names:

• %System%\setting.ini

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

NOTES:

This worm checks for the presence of the file C:\disk.txt.If the said text file exists, it does not drop copies of itself in physical and removable drives, and in network shares. Note that the path to the said file is hardcoded.

For its propagation, it checks if Yahoo! Messenger is installed. If not, it downloads the legitimate installer from the URL http://rd.software.yahoo.com/msgr/8/msgr8us.exe. It adds the user name rnd009 into the contacts list of the logged-in Yahoo! Messenger account.

It sends the following messages in Google Talk and Yahoo! Messenger:

• Happiness is a choice that requires effort at times http://{BLOCKED}.googlepages.com/google.html
• Happiness is not a destination. It is a method of http://{BLOCKED}.googlepages.com/google.html
• Hey Please help me to test my new cam application
• Hey what are you doing Please test my new webcam using private application
• If you want truly to understand something, try to change it http://{BLOCKED}.googlepages.com/google.html
• Now search your google in a HYBRID\DYNAMIC way http://{BLOCKED}.googlepages.com/google.html
• The wisest mind has something yet to learn http://{BLOCKED}.googlepages.com/google.html
• View my private cam via secured connection
• View my webcam (private secured connection using privateCam
• Waiting for you, view my private cam via secured connection

This worm reads the following registry key to check for network shares:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\WorkgroupCrawler\Shares

It then drops the following copies of itself in network shares:

• New Folder.exe
• gphone.exe

It also drops an AUTORUN.INF to automatically execute dropped copies when network drives are accessed. The dropped AUTORUN.INF is detected as MAL_OTORUN2.

This worm deletes all System Restore points.

The file it downloads contains a list of URLs where the malware may download an updated copy of itself.