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TROJ_ZCLICK.GAV

July 30, 2014
 Modified by: Jaime Benigno Reyes
 ALIASES:

PWS:Win32/Zbot.ALZ (Microsoft); Trojan-Spy.Win32.Zbot.tqgi (Kaspersky)

 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:

  • In the wild: Yes

  OVERVIEW

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:

282,750 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

30 Jul 2014

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 and executes them:

  • %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:

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

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.. %Windows% is the Windows folder, which is usually C:\Windows.)

Autostart Technique

This Trojan registers itself as a system service to ensure its automatic execution at every system startup by adding the following registry entries:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\
Services\SecurityCenterServer{number}
ImagePath = "%System%\{random filename 2}.exe -service %Application Data%\{random foldername}\{random filename}.exe"

It 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}

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\{random key}
License = "444"

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}-vaper.su
  • http://{BLOCKED}.{BLOCKED}.92.230:8080
  • http://{BLOCKED}.{BLOCKED}.228.220:443

  SOLUTION

Minimum Scan Engine:

9.700

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

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

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_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services
    • SecurityCenterServer{number}
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • ELowcQ
  • In HKEY_LOCAL_MACHINE\SOFTWARE
    • {random key}

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_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 7

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

Step 8

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