WORM_DOWNAD.FUF

Infection Channel:

Propagates via flashdrives, Copies itself in all available logical drives, Propagates via network shares

This worm arrives via removable drives. It may be dropped by other malware.

It modifies registry entries to disable various system services. This action prevents most of the system functions to be used. It deletes registry entries, causing some applications and programs to not function properly.

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. It exploits software vulnerabilities to propagate to other computers across a network.

It does not have any backdoor routine.

It uses certain lists of user names and passwords to access password-protected shared files.

It prevents users from visiting antivirus-related websites that contain specific strings.

File Size:

162,155 bytes

File Type:

DLL

Initial Samples Received Date:

20 Oct 2010

Payload:

Compromises system security, Compromises network security

Arrival Details

This worm arrives via removable drives.

It may arrive via network shares.

It may be dropped by other malware.

Installation

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

%Application Data%\{random file name}.dll
%System%\{random file name}.dll
%System%\{random number}.tmp
%Program Files%\Internet Explorer\{random file name}.dll
%Program Files%\Movie Maker\{random file name}.dll
%User Temp%\{random file name}.dll

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.. %System% is the Windows system folder, which is usually C:\Windows\System32.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).. %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.)

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\{random characters}
DisplayName = "{random}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random characters}
Type = "32"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random characters}
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random characters}
ErrorControl = "0"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random characters}
ObjectName = "Local System"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random characters}
Description = "{long sentences}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random characters}
ImagePath = "%System Root%\system32\svchost.exe -k netsvcs"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\{random characters}\Parameters
ServiceDll = "%System%\{malware file name}"

It adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random characters} = "rundll32.exe {malware path and file name}, {Parameter}"

Other System Modifications

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Applets
dl = "0"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Applets
ds = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets
ds = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Applets
dl = "0"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\SvcHost
netsvcs = "{original value} {random characters}"

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

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\Tcpip\Parameters
TcpNumConnections = "0x00FFFFFE" - hex values

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

It modifies registry entries to disable the following system services:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\wuauserv
Start = "4"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\WinDefend
Start = "4"