TSPY_ZBOT.VZA

August 19, 2013
 Analysis by: Anthony Joe Melgarejo
 ALIASES:

Win32/Spy.Zbot.AAU trojan (ESET)

 PLATFORM:

Windows 2000, Windows XP (32-bit and 64-bit), Windows Server 2003, Windows Vista (32-bit and 64-bit), Windows 7 (32-bit and 64-bit)

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Spyware

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet

This ZBOT variant was used in a spam run which takes advantage of the UK Tax Return deadline. The said spam message purports to come from HM Revenue and Customs in the UK and informs users of a certain VAT return receipt.

This Spyware may be downloaded by other malware/grayware from remote sites.

It may create registry entries under a certain registry key.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

438,272 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

08 Nov 2013

Payload:

Connects to URLs/IPs, Downloads files, Steals information

Arrival Details

This Spyware may be downloaded by the following malware/grayware from remote sites:

  • TROJ_UPATRE.SMB

It may be downloaded from the following remote sites:

  • https://{BLOCKED}asia.com/logos/astore.exe
  • https://{BLOCKED}gfloorrestoration.com/source/logo.exe

Installation

This Spyware drops the following copies of itself into the affected system:

  • %Application Data%\{random folder name}\{random file name}.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(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It creates the following folders:

  • %Application Data%\{random folder name}

(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(32-bit), XP, and Server 2003(32-bit), or C:\Users\{user name}\AppData\Roaming on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit).)

It adds the following mutexes to ensure that only one of its copies runs at any one time:

  • Global\{GUID}
  • Local\{GUID}

It injects threads into the following normal process(es):

  • explorer.exe

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 file name} = "%Application Data%\{random folder name}\{random file name}.exe"

Other System Modifications

This Spyware adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
{random}

HKEY_CURRENT_USER\Software\Microsoft\
WAB

It may create registry entries under the following registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\GloballyOpenPorts\
List
{random port 1}:UDP = "{random port 1}:UDP:*:Enabled:UDP {random port 1}"

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SharedAccess\Parameters\
FirewallPolicy\StandardProfile\GloballyOpenPorts\
List
{random port 2}:TCP = "{random port 2}:TCP:*:Enabled:TCP {random port 2}"

Download Routine

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

  • http://{pseudorandom domain name}.info
  • http://{pseudorandom domain name}.com
  • http://{pseudorandom domain name}.biz
  • http://{pseudorandom domain name}.net
  • http://{pseudorandom domain name}.org
  • http://{pseudorandom domain name}.ru

Information Theft

This Spyware gathers the following data:

  • Data on cookie files (URLs)
  • FTP credentials
  • Online banking credentials
  • Flashplayer data
  • Personal digital cerificates

Other Details

This Spyware connects to the following URL(s) to check for an Internet connection:

  • http://www.google.com
  • http://www.bing.com

It deletes the initially executed copy of itself

NOTES:

The configuration file may contain the following information:

  • Configuration for stealing online banking account credentials (including targeted banks)
  • Download link to an updated copy of its configuration file
  • Download link to an updated copy of itself
  • Site(s) where it will send its stolen information

  SOLUTION

Minimum Scan Engine:

9.300

Step 1

Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.

Step 2

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

Step 3

Remove the malware/grayware file that dropped/downloaded TSPY_ZBOT.VZA. (Note: Please skip this step if the threat(s) listed below have already been removed.)

    • TROJ_UPATRE.SMB

Step 4

Restart in Safe Mode

[ Learn More ]

Step 5

Delete this registry key

[ 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
    • WAB

Step 6

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 file name} = "%Application Data%\{random folder name}\{random file name}.exe"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\GloballyOpenPorts\List
    • {random port 1}:UDP = "{random port 1}:UDP:*:Enabled:UDP {random port 1}"
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\StandardProfile\GloballyOpenPorts\List
    • {random port 2}:TCP = "{random port 2}:TCP:*:Enabled:TCP {random port 2}"

Step 7

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.
  • %Application Data%\{random folder name}

Step 8

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

Step 9

The following created files/folders/registry keys/registry entries cannot be identified by the user since there are no reference values in the created key. The only way it can be identified is by comparing the present system information with a backup. Note that the said components do not have to be deleted since it won't be harmful to the system.

  • HKEY_CURRENT_USER\Software\Microsoft\{random}


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