ALIASES:

TrojanDownloader:Win32/Carberp.J (Microsoft); RDN/Downloader.a!md (McAfee); Trojan-Downloader.Win32.Agent.fugw (Kaspersky); Trojan.Win32.Generic.pak!cobra (Sunbelt); Trojan horse Generic21.KB (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.

It deletes itself after execution.

  TECHNICAL DETAILS

File Size: 279,769 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 10 Jul 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 creates the following folders:

  • %System Root%\Documents and Settings\Wilbert
  • %Application Data%\Google
  • %Application Data%\Google\Update
  • %System Root%\DOCUME~1
  • %System Root%\DOCUME~1\Wilbert
  • %User Profile%\LOCALS~1
  • %User Temp%\nst7.tmp

(Note: %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.. %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.. %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.)

Other System Modifications

This Trojan deletes the following files:

  • %User Temp%\nsy1.tmp
  • %User Temp%\nst7.tmp

(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 keys:

HKEY_CURRENT_USER\SOFTWARE\Google\
Google Updater

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Google\
Google Updater
value = "20110207"

HKEY_CURRENT_USER\Software\Google\
Google Updater
GUID = "23ab6de3-782a-4d70-a004-f249116ade3b"

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\nsd3.tmp
  • %User Temp%\nst7.tmp\System.dll
  • %User Temp%\nst7.tmp\nsProcess.dll
  • %User Temp%\nst7.tmp\nsSCM.dll
  • %Application Data%\Google\Update\GoogleUpdateBeta.exe

(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.. %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.)

Other Details

This Trojan deletes itself after execution.

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

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\Google
    • Google Updater

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\Google\Google Updater
    • value = "20110207"
  • In HKEY_CURRENT_USER\Software\Google\Google Updater
    • GUID = "23ab6de3-782a-4d70-a004-f249116ade3b"

Step 4

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.
  • %User Temp%\nsd3.tmp
  • %User Temp%\nst7.tmp\System.dll
  • %User Temp%\nst7.tmp\nsProcess.dll
  • %User Temp%\nst7.tmp\nsSCM.dll
  • %Application Data%\Google\Update\GoogleUpdateBeta.exe

Step 5

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.
  • %System Root%\Documents and Settings\Wilbert
  • %Application Data%\Google
  • %Application Data%\Google\Update
  • %System Root%\DOCUME~1
  • %System Root%\DOCUME~1\Wilbert
  • %User Profile%\LOCALS~1
  • %User Temp%\nst7.tmp

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPPER.HPT. 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%\nsy1.tmp
  • %User Temp%\nst7.tmp


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