Analysis by: Kathleen Notario
 PLATFORM:

Windows 98, ME, NT, 2000, XP, Server 2003

 OVERALL RISK RATING:
 REPORTED INFECTION:
 SYSTEM IMPACT RATING:
 INFORMATION EXPOSURE:

  • Threat Type: Adware

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This adware may be dropped by other malware.

It modifies the user's Internet Explorer home page into a certain website. This action allows the malware to point to a website which may contain malware, putting the affected computer at greater risk of malware infection.

  TECHNICAL DETAILS

File Size: 913,408 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 30 Jul 2010

Arrival Details

This adware may be dropped by the following malware:

  • TROJ_DLOADR.TAN

Autostart Technique

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects
{random CLSID} =

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

It creates the following registry entries to enable automatic execution of dropped component at every system startup:

HKEY_CLASSES_ROOT\CLSID
{random CLSID}\\InprocServer32 = (default) = "%System%\{random filename}.dll"

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

Other System Modifications

This adware adds the following registry keys:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Search Bar = "http://www.tangosearch.com/?useie5=1&q=" =

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

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Use Custom Search URL = "1" =

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Main
Search Bar = "http://www.tangosearch.com/?useie5=1&q=" =

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Main
Use Custom Search URL = "1" =

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Toolbar
{random CLSID} = "0" =

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

Web Browser Home Page and Search Page Modification

This adware modifies the user's Internet Explorer home page to the following websites:

  • http://{BLOCKED}angotoolbar.com

  SOLUTION

Minimum Scan Engine: 8.900

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

Remove malware files dropped/downloaded by ADW_TANGO

Step 3

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. Before you could do this, you must restart in Safe Mode. For instructions on how to do this, you may refer to this page If the preceding step requires you to restart in safe mode, you may proceed to edit the system registry.

  • In HKEY_CLASSES_ROOT\CLSID
    • {random CLSID}
  • In HKEY_CURRENT_USER\Software
    • IEBarProperties
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer
    • SearchScopes
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer
    • SearchScopes
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\Browser Helper Objects
    • {random CLSID}
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall
    • {random CLSID}

Step 4

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_CLASSES_ROOT\CLSID\{random CLSID}\InprocServer32
    • (default) = %System%\{random filename}.dll
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Search Bar = http://www.tangosearch.com/?useie5=1&q= Use Custom Search URL = 1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main
    • Search Bar = http://www.tangosearch.com/?useie5=1&q= Use Custom Search URL = 1
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Toolbar
    • {random CLSID} = 0

Step 5

Reset the Internet Explorer Home and Search pages

[ Learn More ]

Step 6

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