Analysis by: Jay Garcia
ALIASES:

Win32:UnwantedSig [PUP] (Avast); PUA:Win32/MyWebSearch (Microsoft)

 PLATFORM:

Windows

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

  • Threat Type: Potentially Unwanted Application

  • Destructiveness: No

  • Encrypted:

  • In the wild: Yes

  OVERVIEW

This Potentially Unwanted Application 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: 385,552 bytes
File Type: EXE
Initial Samples Received Date: 14 Mar 2019

Arrival Details

This Potentially Unwanted Application 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 Potentially Unwanted Application drops the following files:

  • %User Temp%\nsh786A.tmp\nsDialogs.dll
  • %User Temp%\nsh786A.tmp\System.dll
  • %User Temp%\nsh786A.tmp\MDC_msi_bg-copy_1501792562604.bmp
  • %User Temp%\nsh786A.tmp\cancel_blue_1473358017200.bmp
  • %User Temp%\nsh786A.tmp\Install_ENG_1436200260055.bmp
  • %User Temp%\nsh786A.tmp\reporting
  • %User Temp%\nsh786A.tmp\installerParams
  • %User Temp%\CabBDF3.tmp
  • %User Temp%\TarBDF4.tmp
  • %User Temp%\nsh786A.tmp\secondary_bg.png
  • %User Temp%\nsh786A.tmp\secondary_accept.png
  • %User Temp%\nsh786A.tmp\secondary_decline.png
  • %User Temp%\nsh786A.tmp\MDC_msi_bg-copy_1501792573865.bmp
  • %AppDataLocal%\MyDigitalCalendarTooltab\TooltabExtension.dll

(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, 7, and 8.. %AppDataLocal% is the Local Application Data folder, which is usually C:\Documents and Settings\{user name}\Local Settings\Application Data on Windows 2000, XP, and Server 2003, or C:\Users\{user name}\AppData\Local on Windows Vista, 7, and 8.)

Other System Modifications

This Potentially Unwanted Application adds the following registry keys:

HKEY_CURRENT_USER\Software\MyDigitalCalendar

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\TabbedBrowsing

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
MyDigitalCalendarTooltab Uninstall Internet Explorer

It adds the following registry entries:

HKEY_CURRENT_USER\Software\MyDigitalCalendar
Start Page = http://hp.{BLOCKED}y.com/mydigitalcalendar/ttab02/index.html?n=7857F972&p2=^COP^mni000^TTAB02&ptb=201AB8B3-57F1-4E5E-AE7E-66F837C64A4E&coid=063a79206fb5455b9e4c12a0c489f767

HKEY_CURRENT_USER\Software\MyDigitalCalendar
UnInstallSurveyUrl = http://@{downloadDomain}.dl.{BLOCKED}y.com/uninstall.jhtml?surveyUrl=http%3A%2F%2Fwww.research.net%2Fr%2FHYSCVNM%3Fc%3D201AB8B3-57F1-4E5E-AE7E-66F837C64A4E%26ptb%3D^COP^mni000^TTAB02

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\TabbedBrowsing
NewTabPageShow = 1

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
MyDigitalCalendarTooltab
HelpLink = http://support.{BLOCKED}ark.com/

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
MyDigitalCalendarTooltab Uninstall Internet Explorer
Publisher = Mindspark Interactive Network, Inc.

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
MyDigitalCalendarTooltab Uninstall Internet Explorer
UninstallString = Rundll32.exe "%AppDataLocal%\MyDigitalCalendarTooltab\TooltabExtension.dll" U uninstall:MyDigitalCalendar

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Uninstall\
MyDigitalCalendarTooltab Uninstall Internet Explorer
DisplayName = MyDigitalCalendar Internet Explorer Homepage and New Tab

It modifies the following registry entries:

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Start Page = http://hp.{BLOCKED}y.com/mydigitalcalendar/ttab02/index.html?n=7857F972&p2=^COP^mni000^TTAB02&ptb=201AB8B3-57F1-4E5E-AE7E-66F837C64A4E&coid=063a79206fb5455b9e4c12a0c489f767

Other Details

This Potentially Unwanted Application connects to the following possibly malicious URL:

  • http://anx.{BLOCKED}ark.com/anx.gif?anxa=CAPDownloadProcess&anxe=Error&errorCode=-8&errorType=nsisError&errorDetails=b207e4987757c39062e962091566a57491e514db%2Eexe&platform=vicinio&anxv=2.7.1.3000&anxd=2018-05-18&coid=063a79206fb5455b9e4c12a0c489f767&refPartner=^COP^mni000^TTAB02&refSub=&anxl=en-US&anxr=-2039556187&refCobrand=COP&refCampaign=mni000&refTrack=TTAB02&refCountry=
  • https://dp.tb.{BLOCKED}k.com/installerParams.jhtml?coId=063a79206fb5455b9e4c12a0c489f767
  • http://anx.{BLOCKED}ark.com/anx.gif?anxa=CAPDownloadProcess&anxe=Error&errorCode=-13&errorType=nsisError&errorDetails=EmptyPartnerId&platform=vicinio&anxv=2.7.1.3000&anxd=2018-05-18&coid=063a79206fb5455b9e4c12a0c489f767&refPartner=^COP^mni000^TTAB02&refSub=&anxl=en-US&anxr=2044792959&refCobrand=COP&refCampaign=mni000&refTrack=TTAB02&refCountry=