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TSPY_ZBOT.DOCM
Aliases: a variant of Win32/Injector.BAAV trojan (Eset)
Malware type: Spyware
Destructive: No
Platform: Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)
Encrypted: Yes
In the wild: Yes

Overview


Infection Channel: Downloaded from the Internet, Dropped by other malware, Spammed via email

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.

Technical Details


File size: 209,124 bytes
File type: EXE
Memory resident: Yes
Initial samples received date: 19 Mar 2014
Payload: Connects to URLs/IPs, Downloads files

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

Solution


Minimum scan engine: 9.700
First VSAPI Pattern File: 10.674.06
First VSAPI Pattern Release Date: 19 Mar 2014
VSAPI OPR Pattern Version: 10.675.00
VSAPI OPR Pattern Release Date: 20 Mar 2014

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Restart in Safe Mode

[ Learn more ]

Step 3

Delete this registry key

[ Learn more ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.


 
  • In HKEY_CURRENT_USER\Software\Microsoft
    • WAB
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer
    • Privacy

Step 4

Delete this registry value

[ Learn more ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.


  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • {random} = "%Application Data%\{random folder 3}\{random file name}.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • %Windows%\explorer.exe = "%Windows%\explorer.exe:*:Enabled:Windows Explorer"

Step 5

Search and delete these folders

[ Learn more ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.
  • %Application Data%\{random folder 1}
  • %Application Data%\{random folder 2}
  • %Application Data%\{random folder 3}
  • %Application Data%\Microsoft\Address Book

Step 6

Reset Internet security settings

[ Learn more ]

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TSPY_ZBOT.DOCM. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.

Step 8

The following created registry key(s) cannot be identified by the user since there are no reference values in the created key. The only way it can be identified is by comparing the present keys with a backup of the system registry. Note that the said key(s) do not have to be deleted since it won't be harmful to the system:

  • HKEY_CURRENT_USER\Software\Microsoft\{random key}


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