WORM_YAHLOVER.JW

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.

Arrival Details

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.

Installation

This worm drops the following copies of itself into the affected system:

• %Windows%\chrome9.exe
• %System%\chrome9.exe

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.. %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.)

It drops the following files:

• %User Profile%\Desktop\Search.lnk
• %User Profile%\Favorites\Sioril.lnk
• %User Profile%\My Documents\Search bar.lnk
• %User Profile%\Start Menu\Programs\Startup\Search bar.lnk
• %Windows%\Tasks\At1.job

(Note: %User Profile% is the current user's profile folder, which is usually C:\Windows\Profiles\{user name} on Windows 98 and ME, C:\WINNT\Profiles\{user name} on Windows NT, and C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003.. %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
Yahoo Messengger = "%System%\chrome9.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 chrome9.exe"

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

Other System Modifications

This worm modifies the following registry key(s)/entry(ies) as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Start Page = "http://www.chrome10.com/"

(Note: The default value data of the said registry entry is {default homepage}.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Main
Default_Page_URL = "http://www.chrome10.com/"

(Note: The default value data of the said registry entry is {default homepage}.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Main
Default_Search_URL = "http://www.chrome10.com/"

(Note: The default value data of the said registry entry is {default searchpage}.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Main
Search Page = "http://www.chrome10.com/"

(Note: The default value data of the said registry entry is {default searchpage}.)

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Main
Start Page = "http://www.chrome10.com/"

(Note: The default value data of the said registry entry is {default homepage}.)

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:

• chrome9.exe
• New Folder.exe