TSPY_ZBOT.SMIE

 Analysis by: Christopher Daniel So

 ALIASES:

VirTool:Win32/DelfInject.gen!L (Microsoft); Spy-Agent.dp.gen (McAfee)

 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted: No

  • 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.

  TECHNICAL DETAILS

File Size:

Varies

File Type:

PE

Memory Resident:

Yes

Initial Samples Received Date:

25 Feb 2011

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:

  • %System%\twext.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

It drops the following files:

  • %System%\twain_32\local.ds
  • %System%\twain_32\user.ds
  • %System Root%\Documents and Settings\LocalService\Application Data\twain_32\user.ds
  • %System Root%\Documents and Settings\NetworkService\Application Data\twain_32\user.ds

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It creates the following folders:

  • %System%\twain_32
  • %System Root%\Documents and Settings\LocalService\Application Data\twain_32
  • %System Root%\Documents and Settings\NetworkService\Application Data\twain_32

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

Autostart Technique

This spyware modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Userinit = "%System%\userinit.exe,%System%\twext.exe,"

(Note: The default value data of the said registry entry is %System%\userinit.exe,.)

Other System Modifications

This spyware adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Network
UID = "TEU-WINXPSP2_{random hexadecimal number}"

  SOLUTION

Minimum Scan Engine:

8.900

FIRST VSAPI PATTERN FILE:

7.876.04

FIRST VSAPI PATTERN DATE:

04 Mar 2011

VSAPI OPR PATTERN File:

7.877.00

VSAPI OPR PATTERN Date:

04 Mar 2011

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

Identify and delete files detected as TSPY_ZBOT.SMIE using either the Startup Disk or Recovery Console

[ 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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Network
    • UID = "TEU-WINXPSP2_{random hexadecimal number}"

Step 4

Restore this modified 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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Userinit = "%System%\userinit.exe,%System%\twext.exe,"
      To: Userinit = "%System%\userinit.exe,"

Step 5

Search and delete this folder

[ 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.
  • %System%\twain_32
  • %System Root%\Documents and Settings\LocalService\Application Data\twain_32
  • %System Root%\Documents and Settings\NetworkService\Application Data\twain_32

Step 6

Scan your computer with your Trend Micro product to delete files detected as TSPY_ZBOT.SMIE. 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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