Analysis by: Jasen Sumalapao
ALIASES:

PWS:Win32/Zbot (Microsoft), Trojan-Spy.Win32.Zbot.dyzr (Kaspersky), Infostealer (Symantec), Trojan.Win32.Generic!BT (Sunbelt), W32/Zbot.DYZR!tr (Fortinet)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

 OVERALL RISK RATING:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

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 uses a file name similar to a legitimate file to pass as a legitimate file.

It modifies the Internet Explorer Zone Settings.

  TECHNICAL DETAILS

File Size: 210,433 bytes
Initial Samples Received Date: 10 Jul 2012

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 file(s)/component(s):

  • %Application Data%\{Random Folder2}\{Random Filename2}.lol
  • %Application Data%\{Random Folder2}\{Random Filename2}.zoy

(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 copies of itself into the affected system:

  • %Application Data%\{Random Folder1}\{Random Filename1}.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 uses a file name similar to a legitimate file to pass as a legitimate file.

Autostart Technique

This spyware creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{Random Key} = %Application Data%\{Random Folder1}\{Random Filename1}.exe

Other System Modifications

This spyware 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.