TSPY_ZBOT.WEL

December 05, 2013
 Analysis by: Alvin Bacani
 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This spyware may arrive bundled with malware packages as a malware component. 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 lowers the security setting of Internet Explorer.

  TECHNICAL DETAILS

File Size:

1,125,457 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

05 Dec 2013

Arrival Details

This spyware may arrive bundled with malware packages as a malware component.

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 spyware drops the following component file(s):

  • %Application Data%\Microsoft\Address Book\{current user}.wab
  • %Application Data%\{random folder}\{random filename}.{random extension}

(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.)

It drops the following copies of itself into the affected system:

  • %Application Data%\{random folder}\{random filename}.exe

(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.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{random filename} = %Application Data%\{random folder}\{random filename}.exe

Other System Modifications

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

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4
FirstRun = "1"

HKEY_CURRENT_USER\Software\Microsoft\
{random letters}
{random number} = {random data}

It creates the following registry entry(ies) to bypass Windows Firewall:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\AuthorizedApplications\
List
%WINDOWS%\explorer.exe = "%WINDOWS%\explorer.exe:*:Enabled:Windows Explorer"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\DomainProfile\AuthorizedApplications\
List
%Windows%\explorer.exe = "%Windows%\explorer.exe:*:Enabled:Windows Explorer"

Web Browser Home Page and Search Page Modification

This spyware lowers the security setting of Internet Explorer.

Other Details

This spyware connects to the following possibly malicious URL:

  • http://{BLOCKED}r.{BLOCKED}deal.com/web/config/index.php
  • http://{BLOCKED}6.com/exe/install_flash_player.exe
  • http://{BLOCKED}6.com/exe/ups_invoice_execsummary.doc