TROJ_DROPPE.FW

October 24, 2013
 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:

113,664 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

24 Oct 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.

Installation

This Trojan drops the following copies of itself into the affected system:

  • {malware path and file name}.dll
  • %Application Data%\71IVdLUNoO\DHeF268s4.exe

(Note: %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 creates the following folders:

  • %Application Data%\71IVdLUNoO

(Note: %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.)

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\Run
DHeF268s4.exe = "%Application Data%\71IVdLUNoO\DHeF268s4.exe"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
DHeF268s4.exe = "%Application Data%\71IVdLUNoO\DHeF268s4.exe"

It modifies the following registry entries to ensure it automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "cmd.exe"

(Note: The default value data of the said registry entry is Explorer.exe.)

Other System Modifications

This Trojan deletes the following files:

  • %User Temp%\JFy3UobB3
  • %User Temp%\pxTrqmx8
  • %User Temp%\iPnfSBrIXw
  • %User Temp%\Q0iIjYVZMPQ
  • %User Temp%\RMt48KJaIPX
  • %User Temp%\BwGzJSefIy
  • %User Temp%\uEcVl1MrX0

(Note: %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.)

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Command Processor
Autorun = "%Application Data%\71IVdLUNoO\DHeF268s4.exe"

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon
Shell = "cmd.exe"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Command Processor
Autorun = "%Application Data%\71IVdLUNoO\DHeF268s4.exe"

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://{BLOCKED}5.eu/indexrc4.php?{random characters}

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

Identify and delete files detected as TROJ_DROPPE.FW using either the Startup Disk or Recovery Console

[ 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\Microsoft\Windows\CurrentVersion\Run
    • DHeF268s4.exe = "%Application Data%\71IVdLUNoO\DHeF268s4.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • DHeF268s4.exe = "%Application Data%\71IVdLUNoO\DHeF268s4.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Command Processor
    • Autorun = "%Application Data%\71IVdLUNoO\DHeF268s4.exe"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
    • Shell = "cmd.exe"

Step 4

Restore these modified registry values

[ Learn More ]

Important:Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this only if you know how to or you can seek your system administrator's help. You may also check out this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Command Processor
    • Autorun = "%Application Data%\71IVdLUNoO\DHeF268s4.exe"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon
    • From: Shell = "cmd.exe"
      To: Shell = ""Explorer.exe""

Step 5

Search and delete this folder

[ 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%\71IVdLUNoO

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPPE.FW. 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 7

Restore this file from backup only Microsoft-related files will be restored. If this malware/grayware also deleted files related to programs that are not from Microsoft, please reinstall those programs on you computer again.

  • %User Temp%\JFy3UobB3
  • %User Temp%\pxTrqmx8
  • %User Temp%\iPnfSBrIXw
  • %User Temp%\Q0iIjYVZMPQ
  • %User Temp%\RMt48KJaIPX
  • %User Temp%\BwGzJSefIy
  • %User Temp%\uEcVl1MrX0


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