PE_URSNIF.E

This file infector arrives via removable drives. 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 drops copies of itself in removable drives. These dropped copies use the names of the folders located on the said drives for their file names.

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

It connects to certain websites to send and receive information. It deletes the initially executed copy of itself.

Arrival Details

This file infector arrives via removable drives.

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 file infector drops the following files:

• %System%\{random filename}.exe - copy of itself

(Note: %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

It creates the following folders:

• %Application Data%\{random folder name}

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.)

Autostart Technique

This file infector 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\spsrv
Start = "2"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\spsrv
DisplayName = "Windows Protection"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\spsrv
ImagePath = "%System%\{random filename}.exe -k"

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{Random Value} = "%Application Data%\{Random Folder}\{Random Filename}.exe"

File Infection

This file infector infects the following file types:

• .DOC
• .DOCX
• .EXE
• .MSI
• .PDF
• .PPT
• .PPTX
• .XLS
• .XLSX

This is the Trend Micro detection for files infected by:

• PE_URSNIF.E-O

Propagation

This file infector drops copies of itself in removable drives. These dropped copies use the names of the folders located on the said drives for their file names.

Dropping Routine

This file infector drops the following files:

• %Application Data%\{random folder name}\{random filename}.exe - detected as PE_URSNIF.E-O

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming 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.)

It executes the dropped file(s). As a result, malicious routines of the dropped files are exhibited on the affected system.

Other Details

This file infector connects to the following website to send and receive information:

• http://{BLOCKED}.{BLOCKED}.178.40/pki/mscorp/crl/msitwww2.crl

It deletes the initially executed copy of itself

NOTES:

The files this malware infects are located in removable drives and network drives.