ALIASES:

Trojan.Blueso!gen (Symantec); Troj/Malit-EX, Mal/MalitRar-B (Sophos); Trojan horse Ransomer.DOR (AVG)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It disables Task Manager, Registry Editor, and Folder Options.

  TECHNICAL DETAILS

File Size: 849,412 bytes
File Type: EXE
Memory Resident: Yes
Initial Samples Received Date: 08 Sep 2014

Arrival Details

This backdoor 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 backdoor creates the following folders:

  • \Documents and Settings
  • \Documents and Settings\Wilbert
  • \Documents and Settings\Wilbert\3c9n37mr
  • %User Profile%\10.0\Forms
  • %User Profile%\10.0\Collab
  • %User Profile%\10.0\Security
  • %User Profile%\Security\CRLCache

(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.)

Autostart Technique

This backdoor adds the following registry entries to enable its automatic execution at every system startup:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\RunOnce
3c9n37mr = "\DOCUME~1\Wilbert\3c9n37mr\abtx.vbs"

Other System Modifications

This backdoor deletes the following files:

  • %User Startup%\desktop.ini
  • %User Profile%\10.0\ReaderMessages-journal
  • %Application Data%\Adobe\Acrobat\10.0\SharedDataEvents-journal

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.. %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.. %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 adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System

HKEY_CURRENT_USER\Software\Adobe\
Adobe Acrobat\10.0

HKEY_CURRENT_USER\Software\Adobe\
Adobe Synchronizer\10.0

HKEY_LOCAL_MACHINE\System\Acrobatbrokerserverdispatchercpp789

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Installer\
Migrated

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Originals

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\AVGeneral

HKEY_CURRENT_USER\Software\Adobe\
Adobe Synchronizer\10.0\Acrobat.com

HKEY_CURRENT_USER\Software\Adobe\
Adobe Synchronizer\10.0\Acrobat.com.v2

HKEY_CURRENT_USER\Software\Adobe\
Adobe Acrobat\10.0\DiskCabs

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cDocumentCenter

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cDocumentCenter\cSettings

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cEmailDistribution

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cEmailDistribution\cSettings

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cInitiationWizardFirstLaunch

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Security

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Security\
cHandlers

HKEY_LOCAL_MACHINE\Software\Adobe\
Acrobat Reader\10.0\AdobeViewer

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\policies\
system
EnableLUA = "0"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
ShowSuperHidden = "0"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Installer\
Migrated
{AC76BA86-7AD7-1033-7B44-AA0000000001} = "1"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Originals
bDisplayedSplash = "1"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\AVGeneral
bLastExitNormal = "0"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cDocumentCenter
bAlwaysUseServer = "0"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cDocumentCenter
bAlwaysUseServerFD = "0"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cDocumentCenter
bDefault = "1"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cDocumentCenter
bDefaultFD = "1"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cDocumentCenter
tDistMethod = "UPLOAD"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cDocumentCenter\cSettings
tcSetting = "https://api.{BLOCKED}e.acrobat.com"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cDocumentCenter
tUI = "Acrobat.com (Recommended)"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cDocumentCenter
tURL = "urn://ns.{BLOCKED}e.com/Collaboration/SharedReview/Acrobat.com"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cEmailDistribution
bAlwaysUseServerFD = "0"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cEmailDistribution
bDefaultFD = "0"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cEmailDistribution
tDistMethod = "EMAIL"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cEmailDistribution
tUI = "Manually collect responses in my email inbox"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cEmailDistribution
tURL = "urn://ns.{BLOCKED}e.com/Collaboration/Forms/Email"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cInitiationWizardFirstLaunch
bIsFirstLaunchER = "1"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cInitiationWizardFirstLaunch
bIsFirstLaunchFD = "1"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cInitiationWizardFirstLaunch
bIsFirstLaunchSF = "1"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cInitiationWizardFirstLaunch
bIsFirstLaunchSR = "1"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Collab\
cInitiationWizardFirstLaunch
bIsFirstLaunchUF = "1"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\Security\
cHandlers
aPrivKey = "Adobe.PPKLite"

HKEY_LOCAL_MACHINE\SOFTWARE\Adobe\
Acrobat Reader\10.0\AdobeViewer
EULA = "1"

HKEY_CURRENT_USER\Software\Adobe\
Acrobat Reader\10.0\AdobeViewer
EULA = "1"

It creates the following registry entry(ies) to disable Task Manager, Registry Tools and Folder Options:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System
DisableTaskMgr = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NoFolderOptions = "1"

It deletes the following registry keys:

HKEY_CURRENT_USER\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run\
OptionalComponents\IMAIL

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run\
OptionalComponents\MAPI

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run\
OptionalComponents\MSFS

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run\
OptionalComponents

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run

Dropping Routine

This backdoor drops the following files:

  • __tmp_rar_sfx_access_check_66953
  • xotsouerhvvg.LEG
  • ebjpxjdbwm.exe
  • shxwnp.UGF
  • jhlhglofomb.HIS
  • Payment_Advice(2).pdf
  • %User Startup%\start.lnk
  • %Application Data%\Adobe\Color\ACECache11.lst
  • %Application Data%\Adobe\Acrobat\10.0\UserCache.bin
  • %User Temp%\Temporary Internet Files
  • %User Temp%\Temporary Internet Files\Content.IE5
  • %User Temp%\Temporary Internet Files\Content.IE5\EL8ZRUR8
  • %User Temp%\Temporary Internet Files\Content.IE5\C3GXUF8B
  • %User Temp%\Temporary Internet Files\Content.IE5\TMHP3LT9
  • %User Temp%\Temporary Internet Files\Content.IE5\R6MEDUE0
  • %User Temp%\Cookies
  • %User Temp%\History
  • %User Temp%\History\History.IE5
  • %User Profile%\10.0\rdrmessage.zip
  • %User Profile%\10.0\Forms
  • %User Profile%\10.0\Collab
  • %User Profile%\10.0\Security
  • %User Profile%\Security\CRLCache
  • %Windows%\Microsoft.NET\Framework\v2.0.50727\.Identifier

(Note: %User Startup% is the current user's Startup folder, which is usually C:\Windows\Profiles\{user name}\Start Menu\Programs\Startup on Windows 98 and ME, C:\WINNT\Profiles\{user name}\Start Menu\Programs\Startup on Windows NT, and C:\Documents and Settings\{User name}\Start Menu\Programs\Startup.. %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 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.. %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.. %Windows% is the Windows folder, which is usually C:\Windows.)

Other Details

This backdoor connects to the following possibly malicious URL:

  • http://acroipm.{BLOCKED}e.com/10/rdr/ENU/win/nooem/none/message.zip
  • {BLOCKED}0.1
  • {BLOCKED}21.19
  • {BLOCKED}.170.134

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine: 9.700

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

Restart in Safe Mode

[ Learn More ]

Step 3

Enable Registry Editor, Task Manager, and Folder options

[ Learn More ]
By doing this step, you also enable other applications/programs disabled by this malware/grayware/spyware.

Step 4

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\Windows\CurrentVersion\Policies
    • System
  • In HKEY_CURRENT_USER\Software\Adobe\Adobe Acrobat
    • 10.0
  • In HKEY_CURRENT_USER\Software\Adobe\Adobe Synchronizer
    • 10.0
  • In HKEY_LOCAL_MACHINE\System
    • Acrobatbrokerserverdispatchercpp789
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Installer
    • Migrated
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0
    • Originals
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0
    • AVGeneral
  • In HKEY_CURRENT_USER\Software\Adobe\Adobe Synchronizer\10.0
    • Acrobat.com
  • In HKEY_CURRENT_USER\Software\Adobe\Adobe Synchronizer\10.0
    • Acrobat.com.v2
  • In HKEY_CURRENT_USER\Software\Adobe\Adobe Acrobat\10.0
    • DiskCabs
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0
    • Collab
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab
    • cDocumentCenter
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cDocumentCenter
    • cSettings
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab
    • cEmailDistribution
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cEmailDistribution
    • cSettings
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab
    • cInitiationWizardFirstLaunch
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0
    • Security
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Security
    • cHandlers
  • In HKEY_LOCAL_MACHINE\Software\Adobe\Acrobat Reader\10.0
    • AdobeViewer

Step 5

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\RunOnce
    • 3c9n37mr = "\DOCUME~1\Wilbert\3c9n37mr\abtx.vbs"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\policies\system
    • EnableLUA = "0"
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Advanced
    • ShowSuperHidden = "0"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Installer\Migrated
    • {AC76BA86-7AD7-1033-7B44-AA0000000001} = "1"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Originals
    • bDisplayedSplash = "1"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\AVGeneral
    • bLastExitNormal = "0"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cDocumentCenter
    • bAlwaysUseServer = "0"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cDocumentCenter
    • bAlwaysUseServerFD = "0"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cDocumentCenter
    • bDefault = "1"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cDocumentCenter
    • bDefaultFD = "1"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cDocumentCenter
    • tDistMethod = "UPLOAD"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cDocumentCenter\cSettings
    • tcSetting = "https://api.{BLOCKED}e.acrobat.com"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cDocumentCenter
    • tUI = "Acrobat.com (Recommended)"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cDocumentCenter
    • tURL = "urn://ns.{BLOCKED}e.com/Collaboration/SharedReview/Acrobat.com"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cEmailDistribution
    • bAlwaysUseServerFD = "0"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cEmailDistribution
    • bDefaultFD = "0"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cEmailDistribution
    • tDistMethod = "EMAIL"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cEmailDistribution
    • tUI = "Manually collect responses in my email inbox"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cEmailDistribution
    • tURL = "urn://ns.{BLOCKED}e.com/Collaboration/Forms/Email"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cInitiationWizardFirstLaunch
    • bIsFirstLaunchER = "1"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cInitiationWizardFirstLaunch
    • bIsFirstLaunchFD = "1"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cInitiationWizardFirstLaunch
    • bIsFirstLaunchSF = "1"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cInitiationWizardFirstLaunch
    • bIsFirstLaunchSR = "1"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Collab\cInitiationWizardFirstLaunch
    • bIsFirstLaunchUF = "1"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\Security\cHandlers
    • aPrivKey = "Adobe.PPKLite"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Adobe\Acrobat Reader\10.0\AdobeViewer
    • EULA = "1"
  • In HKEY_CURRENT_USER\Software\Adobe\Acrobat Reader\10.0\AdobeViewer
    • EULA = "1"

Step 6

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.
  • __tmp_rar_sfx_access_check_66953
  • xotsouerhvvg.LEG
  • ebjpxjdbwm.exe
  • shxwnp.UGF
  • jhlhglofomb.HIS
  • Payment_Advice(2).pdf
  • %User Startup%\start.lnk
  • %Application Data%\Adobe\Color\ACECache11.lst
  • %Application Data%\Adobe\Acrobat\10.0\UserCache.bin
  • %User Temp%\Temporary Internet Files
  • %User Temp%\Temporary Internet Files\Content.IE5
  • %User Temp%\Temporary Internet Files\Content.IE5\EL8ZRUR8
  • %User Temp%\Temporary Internet Files\Content.IE5\C3GXUF8B
  • %User Temp%\Temporary Internet Files\Content.IE5\TMHP3LT9
  • %User Temp%\Temporary Internet Files\Content.IE5\R6MEDUE0
  • %User Temp%\Cookies
  • %User Temp%\History
  • %User Temp%\History\History.IE5
  • %User Profile%\10.0\rdrmessage.zip
  • %User Profile%\10.0\Forms
  • %User Profile%\10.0\Collab
  • %User Profile%\10.0\Security
  • %User Profile%\Security\CRLCache
  • %Windows%\Microsoft.NET\Framework\v2.0.50727\.Identifier

Step 7

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.
  • \Documents and Settings
  • \Documents and Settings\Wilbert
  • \Documents and Settings\Wilbert\3c9n37mr
  • %User Profile%\10.0\Forms
  • %User Profile%\10.0\Collab
  • %User Profile%\10.0\Security
  • %User Profile%\Security\CRLCache

Step 8

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_SHOTODOR.UQ. 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 9

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 Startup%\desktop.ini
  • %User Profile%\10.0\ReaderMessages-journal
  • %Application Data%\Adobe\Acrobat\10.0\SharedDataEvents-journal

Step 10

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_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion
    • Run
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\OptionalComponents
    • IMAIL
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\OptionalComponents
    • MAPI
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\OptionalComponents
    • MSFS
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    • OptionalComponents
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
    • Run


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