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TROJ_DLOADER.NUQ

April 25, 2013
 ALIASES:

TrojanDownloader:Win32/Small.gen!F (Microsoft); PWS-Bluedit (McAfee); Downloader (Symantec); Trojan-Downloader.Win32.VB.ees (Kaspersky); Trojan.Win32.Generic.pak!cobra (Sunbelt); Trojan horse PSW.Generic6.HWI (AVG)

 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


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:

36,864 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

25 Apr 2013

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.

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
IESet = "IExplorer.dll .dbt"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\RunServices
IESet = "IExplorer.dll .dbt"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
IESet = "IExplorer.dll .dbt"

Other System Modifications

This Trojan adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\RunServices

HKEY_CLASSES_ROOT\.dbt

HKEY_CLASSES_ROOT\DBTFILE\shell\
open\command

It deletes the following registry keys:

HKEY_CLASSES_ROOT\DBTFILE

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.300

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
    • RunServices
  • In HKEY_CLASSES_ROOT
    • .dbt
  • In HKEY_CLASSES_ROOT\DBTFILE\shell\open
    • command

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • IESet = "IExplorer.dll .dbt"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices
    • IESet = "IExplorer.dll .dbt"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • IESet = "IExplorer.dll .dbt"

Step 5

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

Step 6

Restore these deleted registry keys/values from backup

*Note: Only Microsoft-related keys/values will be restored. If the malware/grayware also deleted registry keys/values related to programs that are not from Microsoft, please reinstall those programs on your computer.

  • In HKEY_CLASSES_ROOT
    • DBTFILE


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