TSPY_ZBOT.YUYADI

 Analysis by: David John Agni

 ALIASES:

W32/Zbot.ABV!tr.spy (Fortinet), Trojan-Spy.Win32.Zbot.kth (Kaspersky), PWS:Win32/Zbot (Microsoft), Win32/Spy.Zbot.ABV trojan (ESET-NOD32)

 PLATFORM:

Windows

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 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 modifies the Internet Explorer Zone Settings.

It deletes the initially executed copy of itself.

  TECHNICAL DETAILS

File Size:

314,368 bytes

File Type:

, EXE

Memory Resident:

Yes

Initial Samples Received Date:

21 May 2015

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 and executes them:

  • %Start Menu%\Programs\Accessories\{random filename 1}.exe

(Note: %Start Menu% is the Start Menu folder, where it usually is C:\Documents and Settings\{user name}\Start Menu on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming\Microsoft\Windows\Start Menu on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

It drops the following files:

  • %Application Data%\Microsoft\Network\Connections\Pbk\_hiddenPbk\{random filename 2}.{random extension 1}
  • %Application Data%\Microsoft\Network\Connections\Pbk\_hiddenPbk\{random filename 3}.{random extension 2}

(Note: %Application Data% is the Application Data folder, where it usually is C:\Documents and Settings\{user name}\Application Data on Windows 2000, Windows Server 2003, and Windows XP (32- and 64-bit); C:\Users\{user name}\AppData\Roaming on Windows Vista (32- and 64-bit), Windows 7 (32- and 64-bit), Windows 8 (32- and 64-bit), Windows 8.1 (32- and 64-bit), Windows Server 2008, and Windows Server 2012.)

Other System Modifications

This spyware adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
{random key 1}

HKEY_CURRENT_USER\Software\Microsoft\
{random key 2}

HKEY_CURRENT_USER\Software\Microsoft\
{random key 3}

HKEY_CURRENT_USER\Software\Microsoft\
{random key 4}

HKEY_CURRENT_USER\Software\Microsoft\
{random key 5}

HKEY_CURRENT_USER\Software\Microsoft\
{random key 6}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
{random key 1}
{random value} = "{hex value}"

Web Browser Home Page and Search Page Modification

This spyware modifies the Internet Explorer Zone Settings.

Other Details

This spyware connects to the following possibly malicious URL:

  • http://{BLOCKED}ogyincorp.com/server1/xxx2.jpg

It deletes the initially executed copy of itself

  SOLUTION

Minimum Scan Engine:

9.750

FIRST VSAPI PATTERN FILE:

11.684.08

FIRST VSAPI PATTERN DATE:

23 May 2015

VSAPI OPR PATTERN File:

11.685.00

VSAPI OPR PATTERN Date:

23 May 2015

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

Note that not all files, folders, and registry keys and entries are installed on your computer during this malware's/spyware's/grayware's execution. This may be due to incomplete installation or other operating system conditions. If you do not find the same files/folders/registry information, please proceed to the next step.

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

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
    • {random key 1}
  • In HKEY_CURRENT_USER\Software\Microsoft
    • {random key 2}
  • In HKEY_CURRENT_USER\Software\Microsoft
    • {random key 3}
  • In HKEY_CURRENT_USER\Software\Microsoft
    • {random key 4}
  • In HKEY_CURRENT_USER\Software\Microsoft
    • {random key 5}
  • In HKEY_CURRENT_USER\Software\Microsoft
    • {random key 6}

Step 5

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\{random key 1}
    • {random value} = "{hex value}"

Step 6

Search and delete this file

[ Learn More ]
There may be some files that are hidden. Please make sure you check the Search Hidden Files and Folders checkbox in the "More advanced options" option to include all hidden files and folders in the search result.
  • %Application Data%\Microsoft\Network\Connections\Pbk\_hiddenPbk\{random filename 2}.{random extension 1}
  • %Application Data%\Microsoft\Network\Connections\Pbk\_hiddenPbk\{random filename 3}.{random extension 2}

Step 7

Reset Internet security settings

[ Learn More ]

Step 8

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