TROJ_ZCLICK.WRH

June 28, 2014
 Analysis by: Odessy Silva
 ALIASES:

PWS:Win32/Zbot (Microsoft), Trojan-PSW.Win32.LdPinch.bdxl (Kaspersky), PWSZbot-FBNB!E49C6793FFAA (McAfee)

 PLATFORM:

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

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

  • Threat Type: Trojan

  • Destructiveness: No

  • Encrypted: Yes

  • In the wild: Yes

  OVERVIEW

Infection Channel:

Downloaded from the Internet, Dropped by other malware

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:

324,608 bytes

File Type:

EXE

Memory Resident:

Yes

Payload:

Downloads files, Steals information

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 copies of itself into the affected system:

  • %System%\{random filename 2}.exe
  • %Application Data%\{random foldername}\{random filename}.exe

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %Application Data% is the current user's Application Data folder, which is usually C:\Documents and Settings\{user name}\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Roaming on Windows Vista and 7.)

It drops the following files:

  • %Tasks%\Security Center Update - {number}.job

Autostart Technique

This Trojan adds the following registry entries to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{random entry} = "%Application Data%\{random folder name}\{random filename}.exe"

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
{random entry} = "%Application Data%\{random folder name}\{random filename}.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\ELowcQ

HKEY_LOCAL_MACHINE\SOFTWARE\{random key}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SecurityCenterServer{number}

HKEY_CURRENT_USER\Software\ELowcQ

HKEY_CURRENT_USER\SOFTWARE\{random key}

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Enum\Root\LEGACY_SECURITYCENTERSERVER{number}

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main\FeatureControl\
FEATURE_BROWSER_EMULATION
{random filename}.exe = "00002af9"

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Control\Safeboot

Download Routine

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

  • http://{BLOCKED}rusn.su
  • http://{BLOCKED}der.com
  • http://{BLOCKED}a-red.com
  • http://{BLOCKED}uret.su
  • http://{BLOCKED}ck.su
  • http://{BLOCKED}t-jetr.com

Information Theft

This Trojan s configuration file contains the following information:

  • Search URL (referrer url)
  • Update URL (new C&C)
  • Click URL (redirection url source)
  • Mutex Name
  • Flash URL

NOTES:

It hooks the following APIs:

  • PlaySoundA
  • PlaySoundW
  • WaveOutWrite
  • MessageBoxA
  • MessageBoxW
  • MessageBoxExA
  • MessageBoxExW
  • MessageBoxIndirectA
  • MessageBoxIndirectW
  • RegCloseKey
  • RegEnumKeyExA
  • RegEnumKeyExW
  • RegEnumValueA
  • RegEnumValueW
  • RegOpenKeyA
  • RegOpenKeyW
  • RegOpenKeyExA
  • RegOpenKeyExW
  • RegCreateKeyA
  • RegCreateKeyW
  • RegCreateKeyExA
  • RegCreateKeyExW
  • RegQueryInfoKeyA
  • RegQueryInfoKeyW
  • RegQueryValueExA
  • RegQueryValueExW
  • GetCursorInfo
  • GetMessagePos
  • GetCursorPos
  • SetCursorPos
  • GetMessageA
  • GetMessageW
  • PeekMessageA
  • PeekMessageW

  SOLUTION

Minimum Scan Engine:

9.700

FIRST VSAPI PATTERN FILE:

10.886.05

FIRST VSAPI PATTERN DATE:

17 Jun 2014

VSAPI OPR PATTERN File:

10.887.00

VSAPI OPR PATTERN Date:

26 Jun 2014

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

Scan your computer with your Trend Micro product and note files detected as TROJ_ZCLICK.WRH

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_LOCAL_MACHINE\SOFTWARE
    • ELowcQ
  • In HKEY_CURRENT_USER\Software
    • ELowcQ
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • {random key}
  • In HKEY_CURRENT_USER\SOFTWARE
    • {random key}
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • SecurityCenterServer{number}
  • In HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\Root
    • LEGACY_SECURITYCENTERSERVER{number}

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\Internet Explorer\Main\FeatureControl\FEATURE_BROWSER_EMULATION
    • {random filename}.exe = "00002af9"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\ Windows\CurrentVersion\Run
    • {random entry} = "%Application Data%\{random folder name}\{random filename}.exe"
  • In HKEY_CURRENT_USER\SOFTWARE\Microsoft\ Windows\CurrentVersion\Run
    • random entry} = "%Application Data%\{random folder name}\{random filename}.exe"

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.
  • %Tasks%\Security Center Update - {number}.job

Step 7

Restart in normal mode and scan your computer with your Trend Micro product for files detected as TROJ_ZCLICK.WRH. 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:

Restore Safe Boot Registry Settings

To restore safe boot registry settings:

  1. Open a text editor like Notepad.
  2. Copy and paste the following script:
    • On Windows 2000:
    • On Windows Server 2003:
    • On Windows XP:
    • On Windows Vista:
    • On Windows 7:
  3. Save this file as RESTORE.REG.
  4. Execute the file RESTORE.REG.


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