TSPY_ZBOT.HVA

October 09, 2012
 Analysis by: Kathleen Notario
 ALIASES:

Trojan W32/Zbot.YAI (Norman)

 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.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

195,072 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

16 Nov 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 files:

  • %Application Data%\{random1}\{random}.exe
  • %Application Data%\{random2}\{random}.{random}

(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%\{random1}
  • %Application Data%\{random2}

(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
{random CLSID} = "%Application Data%\{random1}\{random}.exe"

Other System Modifications

This spyware adds the following registry keys as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
{random}

Download Routine

This spyware connects to the following URL(s) to download its configuration file:

  • http://{BLOCKED}n.ru/become.php

Other Details

This spyware deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

8.576.03

FIRST VSAPI PATTERN DATE:

16 Nov 2011

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

Scan your computer with your Trend Micro product and note files detected as TSPY_ZBOT.HVA

Step 3

Restart in Safe Mode

[ Learn More ]

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 CLSID} = "%Application Data%\{random1}\{random}.exe"

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%\{random1}
  • %Application Data%\{random2}

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TSPY_ZBOT.HVA. 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.

NOTES:
The created registry key HKEY_CURRENT_USER\Software\Microsoft\{random} cannot be identified by 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 if the users have one. Note that the key,{random} need not to be deleted since it won't cause the user system any harm.


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