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TROJ_DLOADR.MVB

February 14, 2013
 ALIASES:

Trojan.Win32.Wecod.ys (Kaspersky)

 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:

422,400 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

28 Jan 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:

  • %User Profile%\Application Data\TEMP

(Note: %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.)

Other System Modifications

This Trojan adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\LowRegistry\Worior

HKEY_LOCAL_MACHINE\Software\Licenses

HKEY_CLASSES_ROOT\CLSID\{8F577DD6-A889-B773-13C5-1FBA13C51FBA}

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{8F577DD6-A889-B773-13C5-1FBA13C51FBA}\InprocServer32

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{8F577DD6-A889-B773-13C5-1FBA13C51FBA}\NotInsertable

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{8F577DD6-A889-B773-13C5-1FBA13C51FBA}\ProgID

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{8F577DD6-A889-B773-13C5-1FBA13C51FBA}\VersionIndependentProgID

It adds the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\LowRegistry\Worior
Inform = "True"

HKEY_LOCAL_MACHINE\SOFTWARE\Licenses
{R7C0DB872A3F777C0} = "{random values}"

HKEY_LOCAL_MACHINE\SOFTWARE\Licenses
{K7C0DB872A3F777C0} = "{random values}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{8F577DD6-A889-B773-13C5-1FBA13C51FBA}\InprocServer32
ThreadingModel = "Both"

HKEY_LOCAL_MACHINE\SOFTWARE\Licenses
{I1E98067EA9E38090} = "{random values}"

HKEY_LOCAL_MACHINE\SOFTWARE\Licenses
{01E98067EA9E38090} = "{random values}"

It modifies the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
RFC1156Agent\CurrentVersion\Parameters
TrapPollTimeMilliSecs = "3a98"

(Note: The default value data of the said registry entry is 3a98.)

It deletes the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{8F577DD6-A889-B773-13C5-1FBA13C51FBA}\Version

Dropping Routine

This Trojan drops the following files:

  • %User Temp%\aut1.tmp
  • %User Temp%\aut2.tmp
  • rEvents.dll
  • %User Temp%\0jnUqSj6
  • %User Temp%\0jnUqSj6602_

(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.)

Other Details

This Trojan connects to the following possibly malicious URL:

  • http://s3-sa-east-1.{BLOCKED}aws.com/mocalaoo/Geral.rar

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\Microsoft\Internet Explorer\LowRegistry
    • Worior
  • In HKEY_LOCAL_MACHINE\Software
    • Licenses
  • In HKEY_CLASSES_ROOT\CLSID
    • {8F577DD6-A889-B773-13C5-1FBA13C51FBA}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{8F577DD6-A889-B773-13C5-1FBA13C51FBA}
    • InprocServer32
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{8F577DD6-A889-B773-13C5-1FBA13C51FBA}
    • NotInsertable
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{8F577DD6-A889-B773-13C5-1FBA13C51FBA}
    • ProgID
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{8F577DD6-A889-B773-13C5-1FBA13C51FBA}
    • VersionIndependentProgID

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\Internet Explorer\LowRegistry\Worior
    • Inform = "True"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Licenses
    • {R7C0DB872A3F777C0} = "{random values}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Licenses
    • {K7C0DB872A3F777C0} = "{random values}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{8F577DD6-A889-B773-13C5-1FBA13C51FBA}\InprocServer32
    • ThreadingModel = "Both"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Licenses
    • {I1E98067EA9E38090} = "{random values}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Licenses
    • {01E98067EA9E38090} = "{random values}"

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\RFC1156Agent\CurrentVersion\Parameters
    • From: TrapPollTimeMilliSecs = "3a98"
      To: TrapPollTimeMilliSecs = ""3a98""

Step 5

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%\aut1.tmp
  • %User Temp%\aut2.tmp
  • rEvents.dll
  • %User Temp%\0jnUqSj6
  • %User Temp%\0jnUqSj6602_

Step 6

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.
  • %User Profile%\Application Data\TEMP

Step 7

Scan your computer with your Trend Micro product to delete files detected as TROJ_DLOADR.MVB. 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 8

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_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{8F577DD6-A889-B773-13C5-1FBA13C51FBA}
    • Version


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