TSPY_ZBOT.DOCM

This ZBOT variant is embedded in a .DOCM or macro-enabled document file, which arrives as spammed email attachment.

To get a one-glance comprehensive view of the behavior of this Spyware, refer to the Threat Diagram shown below.

This spyware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It is injected into all running processes to remain memory resident.

It modifies Internet Explorer security settings. This puts the affected computer at greater risk, as it allows malicious URLs to be accessed by the computer.

It deletes itself after execution.

Arrival Details

This spyware 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 copies of itself into the affected system and executes them:

• %Application Data%\{random folder 3}\{random file name}.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.)

It drops the following files:

• %Application Data%\{random folder 1}\{random file name}.{random extension}
• %Application Data%\{random folder 2}\{random file name}.{random extension}
• %Application Data%\Microsoft\Address Book\{user name}.wab
• %Application Data%\Microsoft\Address Book\{user name}.wab~

(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 creates the following folders:

• %Application Data%\{random folder 1}
• %Application Data%\{random folder 2}
• %Application Data%\{random folder 3}
• %Application Data%\Microsoft\Address Book

(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 is injected into all running processes to remain memory resident.

It adds the following mutexes to ensure that only one of its copies runs at any one time:

• Global\{GUID}
• Local\{GUID}

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} = "%Application Data%\{random folder 3}\{random file name}.exe"

Other System Modifications

This spyware adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
{random key}

HKEY_CURRENT_USER\Software\Microsoft\
WAB

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4\WAB File Name

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Privacy

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
{random key}
{random} = "{random}"

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4
OlkContactRefresh = "0"

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4
OlkFolderRefresh = "0"

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

HKEY_CURRENT_USER\Software\Microsoft\
WAB\WAB4\WAB File Name
(Default) = "%Application Data%\Microsoft\Address Book\{user name}.wab"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Privacy
CleanCookies = "0"

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"

Web Browser Home Page and Search Page Modification

This spyware modifies Internet Explorer zone settings.

Download Routine

This spyware connects to the following URL(s) to download its configuration file:

• https://{BLOCKED}reto.ru/mobile/index.php

Other Details

This spyware connects to the following URL(s) to check for an Internet connection:

• http://www.google.com/webhp

It deletes itself after execution.

NOTES:

The configuration file may contain URLs where it downloads an updated copy of itself and where it sends its gathered information.

It may also contain URLs of its target online banking and finance-related sites from where it steals the information.

It may also gather the following information from the affected system:

• Data on cookie files (URLs)
• Email-related information such as account names, email addresses, passwords, server data, and server port
• Email information stored in the user’s Windows Address Book (WAB) file