TROJ_DROPPER.QQA

June 06, 2014
 ALIASES:

Trojan.ADH (Symantec); Trojan.Win32.Inject.nlha (Kaspersky); Mal/MalitRar-C (Sophos); Trojan.Win32.Generic!BT (Sunbelt); Trojan horse Generic10_c.CKCD (AVG)

 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:

  • 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:

1,093,917 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

06 Jun 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 creates the following folders:

  • \Documents and Settings
  • \Documents and Settings\Wilbert
  • \Documents and Settings\Wilbert\nUa94M
  • %User Profile%\Windows\yA1hdaEZ
  • %Windows%\InstallDir

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %Windows% is the Windows folder, which is usually C:\Windows.)

Autostart Technique

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

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
mZo12U = "%User Profile%\nUa94M\vbc.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
HKLM = "%Windows%\InstallDir\windofirewallr.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
HKCU = "%Windows%\InstallDir\windofirewallr.exe"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\SOFTWARE\yA1hdaEZ

It adds the following registry entries:

HKEY_CURRENT_USER\Software\yA1hdaEZ
ServerStarted = "5/29/2014 1:43:07 AM"

HKEY_CURRENT_USER\Software\yA1hdaEZ
InstalledServer = "%Windows%\InstallDir\windofirewallr.exe"

Dropping Routine

This Trojan drops the following files:

  • __tmp_rar_sfx_access_check_43078
  • vbc.exe
  • eHlui.tyhr
  • %User Profile%\yA1hdaEZ\yA1hdaEZ.nfo
  • %User Temp%\x.html
  • %User Profile%\yA1hdaEZ\yA1hdaEZ.svr
  • %Windows%\InstallDir\windofirewallr.exe

(Note: %User Profile% is the current user's profile folder, which is usually C:\Documents and Settings\{user name} on Windows 2000, XP, and Server 2003, or C:\Users\{user name} on Windows Vista and 7.. %User Temp% is the current user's Temp folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Temp on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local\Temp on Windows Vista and 7.. %Windows% is the Windows folder, which is usually C:\Windows.)

This report is generated via an automated analysis system.

  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

Restart in Safe Mode

[ Learn More ]

Step 3

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
    • yA1hdaEZ

Step 4

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\RunOnce
    • mZo12U = "%User Profile%\nUa94M\vbc.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • HKLM = "%Windows%\InstallDir\windofirewallr.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • HKCU = "%Windows%\InstallDir\windofirewallr.exe"
  • In HKEY_CURRENT_USER\Software\yA1hdaEZ
    • ServerStarted = "5/29/2014 1:43:07 AM"
  • In HKEY_CURRENT_USER\Software\yA1hdaEZ
    • InstalledServer = "%Windows%\InstallDir\windofirewallr.exe"

Step 5

Search and delete these components

[ Learn More ]
There may be some components 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.
  • __tmp_rar_sfx_access_check_43078
  • vbc.exe
  • eHlui.tyhr
  • %User Profile%\yA1hdaEZ\yA1hdaEZ.nfo
  • %User Temp%\x.html
  • %User Profile%\yA1hdaEZ\yA1hdaEZ.svr
  • %Windows%\InstallDir\windofirewallr.exe

Step 6

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.
  • \Documents and Settings
  • \Documents and Settings\Wilbert
  • \Documents and Settings\Wilbert\nUa94M
  • %User Profile%\Windows\yA1hdaEZ
  • %Windows%\InstallDir

Step 7

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