ALIASES:

Program:Win32/Youbak.B (Microsoft); Backdoor.Trojan (Symantec); ARC:QuickBatch, ARC:[Youbak_MSN_PARTNER2036.exe]:Inno (Kaspersky); Trojan.Win32.Generic!BT (Sunbelt); Trojan.Generic.5518470 (FSecure)

 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: 1,078,272 bytes
File Type: EXE
Memory Resident: No
Initial Samples Received Date: 21 Jun 2012

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:

  • %User Temp%\is-S4EKO.tmp
  • %User Temp%\is-RIK4O.tmp
  • %User Temp%\is-RIK4O.tmp\_isetup

(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.)

Dropping Routine

This Trojan drops the following files:

  • %Application Data%\Youbak_MSN_PARTNER2036.exe
  • %User Temp%\is-S4EKO.tmp\Youbak_MSN_PARTNER2036.tmp
  • %User Temp%\is-RIK4O.tmp\_isetup\_RegDLL.tmp
  • %User Temp%\is-RIK4O.tmp\_isetup\_shfoldr.dll

(Note: %Application Data% is the current user's Application Data folder, which is usually C:\Windows\Profiles\{user name}\Application Data on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Application Data on Windows NT, and C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003.. %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.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.200

Step 1

For Windows XP and Windows Server 2003 users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

Step 2

Search and delete these files

[ Learn More ]
There may be some component files 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.
  • %Application Data%\Youbak_MSN_PARTNER2036.exe
  • %User Temp%\is-S4EKO.tmp\Youbak_MSN_PARTNER2036.tmp
  • %User Temp%\is-RIK4O.tmp\_isetup\_RegDLL.tmp
  • %User Temp%\is-RIK4O.tmp\_isetup\_shfoldr.dll

Step 3

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.
  • %User Temp%\is-S4EKO.tmp
  • %User Temp%\is-RIK4O.tmp
  • %User Temp%\is-RIK4O.tmp\_isetup

Step 4

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