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TROJ_ZACCESS.UI

October 09, 2012
 Analysis by: Cris Nowell Pantanilla
 PLATFORM:

Windows 2000, Windows XP, Windows Server 2003

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Dropped by other malware, Downloaded from the Internet

This Trojan 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:

192,000 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

28 Jun 2012

Payload:

Connects to URLs/IPs, Downloads files, Modifies system registry

Arrival Details

This Trojan 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 Trojan drops the following files:

  • %Application Data%\{082f346d-1afd-ef95-7a41-5848b36bed23}\@ - list of peer IP addresses
  • %Windows%\Installer\{082f346d-1afd-ef95-7a41-5848b36bed23}\@ - list of peer IP addresses
  • %Application Data%\{082f346d-1afd-ef95-7a41-5848b36bed23}\n - also detected as TROJ_ZACCESS.UI
  • %Windows%\Installer\{082f346d-1afd-ef95-7a41-5848b36bed23}\n - also detected as TROJ_ZACCESS.UI

(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.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

It creates the following folders:

  • %Application Data%\{082f346d-1afd-ef95-7a41-5848b36bed23}
  • %Application Data%\{082f346d-1afd-ef95-7a41-5848b36bed23}\L
  • %Application Data%\{082f346d-1afd-ef95-7a41-5848b36bed23}\U
  • %Windows%\Installer\{082f346d-1afd-ef95-7a41-5848b36bed23}
  • %Windows%\Installer\{082f346d-1afd-ef95-7a41-5848b36bed23}\L
  • %Windows%\Installer\{082f346d-1afd-ef95-7a41-5848b36bed23}\U

(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.. %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

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

  • svchost.exe
  • explorer.exe

Other System Modifications

This Trojan adds the following registry entries as part of its installation routine:

HKEY_CURRENT_USER\Software\Classes\
CLSID\{42aedc87-2188-41fd-b9a3-0c966feabec1}\InprocServer32
(Default) = "%Application Data%\{082f346d-1afd-ef95-7a41-5848b36bed23}\n."

It modifies the following registry entries:

HKEY_CLASSES_ROOT\CLSID\{42aedc87-2188-41fd-b9a3-0c966feabec1}\
InProcServer32
(Default) = "%Application Data%\{082f346d-1afd-ef95-7a41-5848b36bed23}\n."

(Note: The default value data of the said registry entry is "%SystemRoot%\system32\shdocvw.dll".)

HKEY_CLASSES_ROOT\CLSID\{42aedc87-2188-41fd-b9a3-0c966feabec1}\
InProcServer32
ThreadingModel = "Both"

(Note: The default value data of the said registry entry is "Apartment".)

HKEY_CLASSES_ROOT\CLSID\{F3130CDB-AA52-4C3A-AB32-85FFC23AF9C1}\
InprocServer32
(Default) = "\.\globalroot\systemroot\Installer\{082f346d-1afd-ef95-7a41-5848b36bed23}\n."

(Note: The default value data of the said registry entry is "%Windows%\system32\wbem\wbemess.dll".)

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{F3130CDB-AA52-4C3A-AB32-85FFC23AF9C1}\InprocServer32
(Default) = "\.\globalroot\systemroot\Installer\{082f346d-1afd-ef95-7a41-5848b36bed23}\n."

(Note: The default value data of the said registry entry is "%Windows%\system32\wbem\wbemess.dll".)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}unter.co/count.php

NOTES:

This Trojan accesses the following site to know its location:

  • http://{BLOCKED}s.{BLOCKED}g.com/geo/txt/city.php

It may also create a hidden connection to a remote web site as an ad-click fraud routine.

It may connect to a peer using port 16464 to download other malware or updated copies of itself.

  SOLUTION

Minimum Scan Engine:

9.200

FIRST VSAPI PATTERN FILE:

9.222.06

FIRST VSAPI PATTERN DATE:

28 Jun 2012

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

Restart in Safe Mode

[ 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_CURRENT_USER\Software\Classes\CLSID
    • {42aedc87-2188-41fd-b9a3-0c966feabec1}

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_CLASSES_ROOT\CLSID\{42aedc87-2188-41fd-b9a3-0c966feabec1}\InProcServer32
    • From: (Default) = "%Application Data%\{082f346d-1afd-ef95-7a41-5848b36bed23}\n."
      To: (Default) = "%SystemRoot%\system32\shdocvw.dll"
  • In HKEY_CLASSES_ROOT\CLSID\{42aedc87-2188-41fd-b9a3-0c966feabec1}\InProcServer32
    • From: ThreadingModel = "Both"
      To: ThreadingModel = "Apartment"
  • In HKEY_CLASSES_ROOT\CLSID\{F3130CDB-AA52-4C3A-AB32-85FFC23AF9C1}\InprocServer32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{F3130CDB-AA52-4C3A-AB32-85FFC23AF9C1}\InprocServer32

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%\{082f346d-1afd-ef95-7a41-5848b36bed23}
%Windows%\Installer\{082f346d-1afd-ef95-7a41-5848b36bed23}

Step 6

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