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TROJ_DROPPER.UAU

July 08, 2013
 ALIASES:

Trojan:Win32/Vecebot.A (Microsoft); Trojan.Gen (Symantec); Backdoor.Win32.Vecebot.a (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt)

 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:

462,336 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

08 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:

  • %Program Files%\Common Files\Windows Update Components

(Note: %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\KB834789.tmp
  • %Program Files%\Common Files\Windows Update Components\UsrClass.ini
  • %Program Files%\Common Files\Windows Update Components\wuauserv.dll
  • %Program Files%\Common Files\Windows Update Components\wuauclt.exe
  • %User Temp%\c8.tmp.new

(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.. %Program Files% is the default Program Files folder, usually C:\Program Files in Windows 2000, Server 2003, and XP (32-bit), Vista (32-bit), and 7 (32-bit), or C:\Program Files (x86) in Windows XP (64-bit), Vista (64-bit), and 7 (64-bit).)

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

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%\KB834789.tmp
  • %Program Files%\Common Files\Windows Update Components\UsrClass.ini
  • %Program Files%\Common Files\Windows Update Components\wuauserv.dll
  • %Program Files%\Common Files\Windows Update Components\wuauclt.exe
  • %User Temp%\c8.tmp.new

Step 3

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.
  • %Program Files%\Common Files\Windows Update Components

Step 4

Scan your computer with your Trend Micro product to delete files detected as TROJ_DROPPER.UAU. 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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