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WORM_ZBOT.GJ
Aliases: PWS:Win32/Zbot (Microsoft); Trojan-Spy.Win32.Zbot.maes
Malware type: Worm
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: Dropped by other malware, Downloaded from the Internet, Propagates via removable drives

This worm 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.

It attempts to steal sensitive online banking information, such as user names and passwords. This routine risks the exposure of the user's account information, which may then lead to the unauthorized use of the stolen data.

Technical Details


File size: 288,256 bytes
File type: EXE
Memory resident: Yes
Initial samples received date: 06 Jun 2013
Payload: Steals information, Downloads files

Arrival Details

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

  • %Application Data%\{Random Folder 1}\{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.)

It drops the following component file(s):

  • %Application Data%\{Random Folder 2}\{Random Filename and Extension}
  • %Application Data%\{Random Folder 3}\{Random Filename and 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.)

Autostart Technique

This worm 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 1}\{Random Filename}.exe

Other System Modifications

This worm 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 worm lowers the security setting of Internet Explorer.

Download Routine

This worm connects to the following website(s) to download and execute a malicious file:

  • http://{BLOCKED}vers.ru/sexy/files/build.exe

Information Theft

This worm attempts to steal sensitive online banking information, such as user names and passwords. This routine risks the exposure of the user's account information, which may then lead to the unauthorized use of the stolen data.

Its configuration file contains the following information:

  • http://{BLOCKED}ionhunter.ru/sexy/file.php
  • http://{BLOCKED}funsite.ru/sexy/file.php

Other Details

The configuration file may contain URLs that it access to download an updated copy of itself and to send its gathered information.

NOTES:

It then drops a .LNK file (Shortcut file) on the removable drive, which points to the path and filename of the dropped copy of the malware on the removable drive.

Solution


Minimum scan engine: 9.300
First VSAPI Pattern File: 9.972.03
First VSAPI Pattern Release Date: 10 Jun 2013
VSAPI OPR Pattern Version: 9.973.00
VSAPI OPR Pattern Release Date: 11 Jun 2013

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 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 1}\{Random Filename}.exe
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
    • "%Windows%"\explorer.exe = "%Windows%"\explorer.exe:*:Enabled:Windows Explorer

Step 4

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}

Step 5

Reset Internet security settings

[ Learn more ]

Step 6

Scan your computer with your Trend Micro product to delete files detected as WORM_ZBOT.GJ. 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.


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Analysis By: Rika Joi Gregorio

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