TSPY_ZBOT.DBJ
PWS:Win32/Zbot (Microsoft); Trojan-Spy.Win32.Zbot.cqpr (Kaspersky)
Windows 2000, Windows, XP, Windows Server 2003

Threat Type: Spyware
Destructiveness: No
Encrypted:
In the wild: Yes
OVERVIEW
This spyware monitors the browser activities of the affected system, specifically the address bar. It may also insert additional fields in forms to obtain other information from the user.
This spyware arrives as attachment to mass-mailed email messages. 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 modifies the Internet Explorer Zone Settings.
As of this writing, the said sites are inaccessible.
TECHNICAL DETAILS
Arrival Details
This spyware arrives as attachment to mass-mailed email messages.
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 copies of itself into the affected system:
- %Application Data%\{random folder name 1}\{random file name 1}.exe
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)
It drops the following files:
- %Application Data%\{random folder name 2}\{random file name 2}.{3 random alphabetic character extension name} - encrypted data
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)
It creates the following folders:
- %Application Data%\{random folder name 1}
- %Application Data%\{random folder name 2}
(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.)
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
{GUID} = "%Application Data%\{random folder name 1}\{random file name 1}.exe"
Other System Modifications
This spyware adds the following registry keys as part of its installation routine:
HKEY_CURRENT_USER\Software\Microsoft\
{random key}
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 the Internet Explorer Zone Settings.
Download Routine
This spyware connects to the following URL(s) to download its configuration file:
- http://{BLOCKED}fox.ru/mychristmax.php
As of this writing, the said sites are inaccessible.
NOTES:
The configuration file contains a list of banking websites that will be monitored by the malware. It also contains the drop zone and the URL where a backup configuration file can be downloaded.
Information Theft
It monitors the browser activities of the affected system, specifically the address bar. It may also insert additional fields in forms to obtain other information from the user.
SOLUTION
Step 1
For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.
Step 2
Restart in Safe Mode
Step 3
Delete this registry value
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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\AuthorizedApplications\List
- %Windows%\explorer.exe = %Windows%\explorer.exe:*:Enabled:Windows Explorer
- %Windows%\explorer.exe = %Windows%\explorer.exe:*:Enabled:Windows Explorer
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
- {GUID} = %Application Data%\{random folder name 1}\{random file name 1}.exe
- {GUID} = %Application Data%\{random folder name 1}\{random file name 1}.exe
Step 4
Delete this registry key
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
- {random key}
- {random key}
Step 5
Search and delete these folders
- %Application Data%\{random folder name 1}
- %Application Data%\{random folder name 2}
Step 6
Reset Internet security settings
Step 7
Restart in normal mode and scan your computer with your Trend Micro product for files detected as TSPY_ZBOT.DBJ. 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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