ADW_DEFTAB

January 09, 2014
 Analysis by: Jimelle Monteser
 ALIASES:

a variant of Win32/Toolbar.DefaultTab.B application (NOD32)

 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:
 INFORMATION EXPOSURE:

  • Threat Type: Adware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This adware arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites. It arrives as a component bundled with malware/grayware packages.

  TECHNICAL DETAILS

File Size:

50,296 bytes

File Type:

EXE

Memory Resident:

Yes

Initial Samples Received Date:

08 Jan 2014

Arrival Details

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

It arrives as a component bundled with malware/grayware packages.

Installation

This adware drops the following files:

  • {malware path}\DefaultTabBHO.cfg
  • %User Profile%\ntuser.pol
  • %System%\GroupPolicy\gpt.ini
  • %System%\GroupPolicy\User\Registry.pol

(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.. %System% is the Windows system folder, which is usually C:\Windows\System32.)

It creates the following folders:

  • %System%\GroupPolicy
  • %System%\GroupPolicy\Machine
  • %System%\GroupPolicy\User

(Note: %System% is the Windows system folder, which is usually C:\Windows\System32.)

Autostart Technique

This adware adds the following registry keys to install itself as a Browser Helper Object (BHO):

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Ext

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Ext\CLSID

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon\
GPExtensions

HKEY_CURRENT_USER\Software\Microsoft\
Windows NT\CurrentVersion\Winlogon\
GPExtensions\{CLSID}

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowser

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowser\CLSID

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowser\CurVer

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowser.1

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowser.1\CLSID

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowserActiveX

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowserActiveX\CLSID

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowserActiveX\CurVer

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowserActiveX.1

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowserActiveX.1\CLSID

HKEY_LOCAL_MACHINE\Software\Classes\
AppID\DefaultTabBHO.DLL

HKEY_LOCAL_MACHINE\Software\Classes\
AppID\{CLSID}

HKEY_LOCAL_MACHINE\Software\Classes\
CLSID\{CLSID}

HKEY_LOCAL_MACHINE\Software\Classes\
CLSID\{CLSID}\InprocServer32

HKEY_LOCAL_MACHINE\Software\Classes\
CLSID\{CLSID}\ProgID

HKEY_LOCAL_MACHINE\Software\Classes\
CLSID\{CLSID}\Programmable

HKEY_LOCAL_MACHINE\Software\Classes\
CLSID\{CLSID}\TypeLib

HKEY_LOCAL_MACHINE\Software\Classes\
CLSID\{CLSID}\VersionIndependentProgID

HKEY_LOCAL_MACHINE\Software\Classes\
Interface\{CLSID}

HKEY_LOCAL_MACHINE\Software\Classes\
Interface\{CLSID}\ProxyStubClsid

HKEY_LOCAL_MACHINE\Software\Classes\
Interface\{CLSID}\ProxyStubClsid32

KEY_LOCAL_MACHINE\Software\Classes\
Interface\{CLSID}\TypeLib

HKEY_LOCAL_MACHINE\Software\Classes\
TypeLib\{CLSID}

HKEY_LOCAL_MACHINE\Software\Classes\
TypeLib\{CLSID}\1.0

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowser

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowser\CLSID

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowser\CurVer

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowser.1

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowser.1\CLSID

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowserActiveX

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowserActiveX\CLSID

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowserActiveX\CurVer

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowserActiveX.1

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowserActiveX.1\CLSID

HKEY_CLASSES_ROOT\AppID\DefaultTabBHO.DLL

HKEY_CLASSES_ROOT\AppID\{CLSID}

HKEY_CLASSES_ROOT\CLSID\{CLSID}

HKEY_CLASSES_ROOT\CLSID\{CLSID}\
InprocServer32

HKEY_CLASSES_ROOT\CLSID\{CLSID}\
ProgID

HKEY_CLASSES_ROOT\CLSID\{CLSID}\
Programmable

HKEY_CLASSES_ROOT\CLSID\{CLSID}\
TypeLib

HKEY_CLASSES_ROOT\CLSID\{CLSID}\
VersionIndependentProgID

HKEY_CLASSES_ROOT\Interface\{CLSID}

HKEY_CLASSES_ROOT\Interface\{CLSID}\
ProxyStubClsid

HKEY_CLASSES_ROOT\Interface\{CLSID}\
ProxyStubClsid32

HKEY_CLASSES_ROOT\Interface\{CLSID}\
TypeLib

HKEY_CLASSES_ROOT\TypeLib\{CLSID}

HKEY_CLASSES_ROOT\TypeLib\{CLSID}\
1.0

HKEY_CLASSES_ROOT\TypeLib\{CLSID}\
1.0\0

HKEY_CLASSES_ROOT\TypeLib\{CLSID}\
1.0\0\win32

HKEY_CLASSES_ROOT\TypeLib\{CLSID}\
1.0\FLAGS

HKEY_CLASSES_ROOT\TypeLib\{CLSID}\
1.0\HELPDIR

EY_CURRENT_USER\Software\AppDataLow

HKEY_CURRENT_USER\Software\AppDataLow\
Software

HKEY_CURRENT_USER\Software\AppDataLow\
Software\DefaultTab

HKEY_CURRENT_USER\Software\AppDataLow\
Software\DefaultTab\BHO

HKEY_CURRENT_USER\Software\DefaultTab

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\ApprovedExtensionMigration{CLSID}

HKEY_LOCAL_MACHINE\Software\Classes\
TypeLib\{CLSID}\1.0\
0

HKEY_LOCAL_MACHINE\Software\Classes\
TypeLib\{CLSID}\1.0\
0\win32

HKEY_LOCAL_MACHINE\Software\Classes\
TypeLib\{CLSID}\1.0\
FLAGS

HKEY_LOCAL_MACHINE\Software\Classes\
TypeLib\{CLSID}\1.0\
HELPDIR

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{CLSID}

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Ext\
PreApproved\{CLSID}

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\policies\
Ext

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{CLSID}

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Group Policy\
History

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Group Policy\
History\{CLSID}

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Group Policy\
History\{CLSID}\0

Other System Modifications

This adware adds the following registry entries as part of its installation routine:

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowser
Default = "DefaulTab Browser Helper"

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowser\CLSID
Default = "{CLSID}"

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowser\CurVer
Default = "DefaultTabBHO.DefaultTabBrowser.1"

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowser.1
Default = "DefaulTab Browser Helper"

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowser.1\CLSID
Default = "{CLSID}"

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowserActiveX
Default = "DefaultTabBrowserActiveX Class"

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowserActiveX\CLSID
Default = "{CLSID}"

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowserActiveX\CurVer
Default = "DefaultTabBrowserActiveX.1"

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowserActiveX.1
Default = "DefaultTabBrowserActiveX.1 Class"

HKEY_CLASSES_ROOT\DefaultTabBHO.DefaultTabBrowserActiveX.1\CLSID
Default = "{CLSID}"

HKEY_CLASSES_ROOT\AppID\DefaultTabBHO.DLL
AppID = "{AppID}"

HKEY_CLASSES_ROOT\AppID\{CLSID}
Default = "DefaultTabBHO"

HKEY_CLASSES_ROOT\CLSID\{CLSID}
Default = "DefaultTab Browser Helper"

HKEY_CLASSES_ROOT\CLSID\{CLSID}\
InprocServer32
Default = "{malware path}\{malware filename}.dll"

HKEY_CLASSES_ROOT\CLSID\{CLSID}\
InprocServer32
Threading Model = "Apartment"

HKEY_CLASSES_ROOT\CLSID\{CLSID}\
ProgID
Default = "DefaultTabBHO.DefaultTabBrowser.1"

HKEY_CLASSES_ROOT\CLSID\{CLSID}\
TypeLib
Default = "{CLSID}"

HKEY_CLASSES_ROOT\CLSID\{CLSID}\
VersionIndependentProgID
Default = "DefaultTabBHO.DefaultTabBrowser"

HKEY_CLASSES_ROOT\Interface\{CLSID}
Default = "IDefaultTabBrowser"

HKEY_CLASSES_ROOT\Interface\{CLSID}\
TypeLib
Version = "1.0"

HKEY_CLASSES_ROOT\TypeLib\{CLSID}\
1.0
Default = "DefaultTabBHO 1.0 Type Library"

HKEY_CLASSES_ROOT\TypeLib\{CLSID}\
1.0\0\win32
Default = "{malware path}\{malware filename}.dll"

HKEY_CLASSES_ROOT\TypeLib\{CLSID}\
1.0\FLAGS
Default = "0"

HKEY_CLASSES_ROOT\TypeLib\{CLSID}\
1.0\HELPDIR
Default = "{malware path}"

HKEY_CURRENT_USER\Software\DefaultTab
IE ID = "{IE ID}"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{CLSID}
Default = "DefaultTabBHO"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{CLSID}
NoExplorer = "1"

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowser
Default = "DefaulTab Browser Helper"

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowser\CLSID
Default = "{CLSID}"

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowser\CurVer
Default = "DefaultTabBHO.DefaultTabBrowser.1"

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowser.1
Default = "DefaulTab Browser Helper"

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowser.1\CLSID
Default = "{CLSID}"

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowserActiveX
Default = "DefaultTabBrowserActiveX Class"

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowserActiveX\CLSID
Default = "{CLSID}"

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowserActiveX\CurVer
Default = "DefaultTabBrowserActiveX.1"

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowserActiveX.1
Default = "DefaultTabBrowserActiveX.1 Class"

HKEY_LOCAL_MACHINE\Software\Classes\
DefaultTabBHO.DefaultTabBrowserActiveX.1\CLSID
Default = "{CLSID}"

HKEY_LOCAL_MACHINE\Software\Classes\
AppID\DefaultTabBHO.DLL
AppID = "{AppID}"

HKEY_LOCAL_MACHINE\Software\Classes\
AppID\{CLSID}
Default = "DefaultTabBHO"

HKEY_LOCAL_MACHINE\Software\Classes\
CLSID\{CLSID}
Default = "DefaultTab Browser Helper"

HKEY_LOCAL_MACHINE\Software\Classes\
CLSID\{CLSID}\InprocServer32
Default = "{malware path}\{malware filename}.dll"

HKEY_LOCAL_MACHINE\Software\Classes\
CLSID\{CLSID}\InprocServer32
Threading Model = "Apartment"

HKEY_LOCAL_MACHINE\Software\Classes\
CLSID\{CLSID}\ProgID
Default = "DefaultTabBHO.DefaultTabBrowser.1"

HKEY_LOCAL_MACHINE\Software\Classes\
CLSID\{CLSID}\TypeLib
Default = "{CLSID}"

HKEY_LOCAL_MACHINE\Software\Classes\
CLSID\{CLSID}\VersionIndependentProgID
Default = "DefaultTabBHO.DefaultTabBrowser"

HKEY_LOCAL_MACHINE\Software\Classes\
Interface\{CLSID}
Default = "IDefaultTabBrowser"

HKEY_LOCAL_MACHINE\Software\Classes\
Interface\{CLSID}\TypeLib
Version = "1.0"

HKEY_LOCAL_MACHINE\Software\Classes\
TypeLib\{CLSID}\1.0
Default = "DefaultTabBHO 1.0 Type Library"

HKEY_LOCAL_MACHINE\Software\Classes\
TypeLib\{CLSID}\1.0\
0\win32
Default = "{malware path}\{malware filename}.dll"

HKEY_LOCAL_MACHINE\Software\Classes\
TypeLib\{CLSID}\1.0\
FLAGS
Default = "0"

HKEY_LOCAL_MACHINE\Software\Classes\
TypeLib\{CLSID}\1.0\
HELPDIR
Default = "{malware path}"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{CLSID}
Default = "DefaultTabBHO"

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{CLSID}
NoExplorer = "1"

Other Details

This adware connects to the following possibly malicious URL:

  • api.{BLOCKED}tab.com/toolbar/install
  • api.{BLOCKED}tab.com/toolbar/open

  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

Identifying the Grayware Files

Download the latest spyware pattern file and scan your computer. Note the path and file name of all files detected as ADW_DEFTAB.

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Close all opened browser windows

Step 5

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_CLASSES_ROOT
    • DefaultTabBHO.DefaultTabBrowser
  • In HKEY_CLASSES_ROOT
    • DefaultTabBHO.DefaultTabBrowser.1
  • In HKEY_CLASSES_ROOT
    • DefaultTabBHO.DefaultTabBrowserActiveX
  • In HKEY_CLASSES_ROOT
    • DefaultTabBHO.DefaultTabBrowserActiveX.1
  • In HKEY_CLASSES_ROOT\AppID
    • DefaultTabBHO.DLL
  • In HKEY_CLASSES_ROOT\AppID
    • {CLSID}
  • In HKEY_CLASSES_ROOT\CLSID
    • {CLSID}
  • In HKEY_CLASSES_ROOT\Interface
    • {CLSID}
  • In HKEY_CLASSES_ROOT\TypeLib
    • {CLSID}
  • In HKEY_CURRENT_USER\Software
    • AppDataLow
  • In HKEY_CURRENT_USER\Software
    • DefaultTab
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer
    • ApprovedExtensionMigration{CLSID}
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer
    • Browser Helper Objects
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Group Policy
    • History
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies
    • Ext
  • In HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
    • GPExtensions
  • In HKEY_LOCAL_MACHINE\Software\Classes
    • DefaultTabBHO.DefaultTabBrowser
  • In HKEY_LOCAL_MACHINE\Software\Classes
    • DefaultTabBHO.DefaultTabBrowser.1
  • In HKEY_LOCAL_MACHINE\Software\Classes
    • DefaultTabBHO.DefaultTabBrowserActiveX
  • In HKEY_LOCAL_MACHINE\Software\Classes
    • DefaultTabBHO.DefaultTabBrowserActiveX.1
  • In HKEY_LOCAL_MACHINE\Software\Classes\AppID
    • DefaultTabBHO.DLL
  • In HKEY_LOCAL_MACHINE\Software\Classes\AppID
    • {CLSID}
  • In HKEY_LOCAL_MACHINE\Software\Classes\CLSID
    • {CLSID}
  • In HKEY_LOCAL_MACHINE\Software\Classes\Interface
    • {CLSID}
  • In HKEY_LOCAL_MACHINE\Software\Classes\TypeLib
    • {CLSID}
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects
    • {CLSID}
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Ext\PreApproved
    • {CLSID}
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\policies
    • Ext

Step 6

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%\GroupPolicy

Step 7

Search and delete this file

[ Learn More ]
There may be some 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.
  • {malware path}\DefaultTabBHO.cfg
  • %User Profile%\ntuser.pol

Step 8

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