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TROJ_SMALL.GT

October 12, 2012
 ALIASES:

Trojan:Win32/Startpage.RA (Microsoft); Generic.bfr!ci (McAfee); Trojan.Startpage (Symantec); PAK:FSG, Trojan-Downloader.Win32.Agent.jn (Kaspersky); Trojan-Downloader.Win32.Femad.gen (fs) (Sunbelt); Packer.FSG.A (FSecure)

 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:

28,944 bytes

File Type:

EXE

Memory Resident:

No

Initial Samples Received Date:

25 Jan 2012

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.

Autostart Technique

This Trojan registers itself as a BHO to ensure its automatic execution every time Internet Explorer is used by adding the following registry keys:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Browser Helper Objects\{ED7893AD-F566-4702-B1E9-CE3201BDCD87}

Other System Modifications

This Trojan deletes the following files:

  • %Windows%\msn.hta
  • %System Root%\filter.log

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.. %System Root% is the root folder, which is usually C:\. It is also where the operating system is located.)

It adds the following registry keys:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
SearchAssistant Uninstall

HKEY_CLASSES_ROOT\CLSID\{1976A8B3-8E7E-482E-BDDF-AE39F8856C97}\
InProcServer32

HKEY_CLASSES_ROOT\PROTOCOLS\Filter\
text/html

HKEY_CLASSES_ROOT\PROTOCOLS\Filter\
text/plain

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Search

HKEY_LOCAL_MACHINE\Software\Microsoft\
Internet Explorer\New Windows

HKEY_CLASSES_ROOT\CLSID\{ED7893AD-F566-4702-B1E9-CE3201BDCD87}\
InProcServer32

It adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
SearchAssistant Uninstall
DisplayName = "Search Assistant Uninstall"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Uninstall\
SearchAssistant Uninstall
UninstallString = "regsvr32 /s /u %System%\miki.dll"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{1976A8B3-8E7E-482E-BDDF-AE39F8856C97}\InProcServer32
ThreadingModel = "Apartment"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
PROTOCOLS\Filter\text/html
CLSID = "{1976A8B3-8E7E-482E-BDDF-AE39F8856C97}"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
PROTOCOLS\Filter\text/plain
CLSID = "{1976A8B3-8E7E-482E-BDDF-AE39F8856C97}"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Start Page = "about:blank"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
HOMEOldSP = "about:blank"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Search Bar = "res://%User Temp%\sp.dll/sp.html"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Search Page = "about:blank"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Use Search Asst = "no"

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

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Search
SearchAssistant = "about:blank"

HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\New Windows
PopupMgr = "no"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Main
Start Page = "about:blank"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Main
HOMEOldSP = "about:blank"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Main
Search Bar = "res://%User Temp%\sp.dll/sp.html"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Main
Search Page = "about:blank"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Main
Use Search Asst = "no"

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

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Search
SearchAssistant = "about:blank"

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\New Windows
PopupMgr = "no"

HKEY_LOCAL_MACHINE\SOFTWARE\Classes\
CLSID\{ED7893AD-F566-4702-B1E9-CE3201BDCD87}\InProcServer32
ThreadingModel = "Apartment"

Dropping Routine

This Trojan drops the following files:

  • %System%\miki.dll
  • %User Temp%\sp.dll
  • %System%\sqlppmo.dll

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003.. %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.)

This report is generated via an automated analysis system.

  SOLUTION

Minimum Scan Engine:

9.200

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

Close all opened browser windows

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.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall
    • SearchAssistant Uninstall
  • In HKEY_CLASSES_ROOT\CLSID\{1976A8B3-8E7E-482E-BDDF-AE39F8856C97}
    • InProcServer32
  • In HKEY_CLASSES_ROOT\PROTOCOLS\Filter
    • text/html
  • In HKEY_CLASSES_ROOT\PROTOCOLS\Filter
    • text/plain
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer
    • Search
  • In HKEY_LOCAL_MACHINE\Software\Microsoft\Internet Explorer
    • New Windows
  • In HKEY_CLASSES_ROOT\CLSID\{ED7893AD-F566-4702-B1E9-CE3201BDCD87}
    • InProcServer32

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_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\SearchAssistant Uninstall
    • DisplayName="Search Assistant Uninstall"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\SearchAssistant Uninstall
    • UninstallString="regsvr32 /s /u %System%\miki.dll"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{1976A8B3-8E7E-482E-BDDF-AE39F8856C97}\InProcServer32
    • ThreadingModel="Apartment"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\PROTOCOLS\Filter\text/html
    • CLSID="{1976A8B3-8E7E-482E-BDDF-AE39F8856C97}"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\PROTOCOLS\Filter\text/plain
    • CLSID="{1976A8B3-8E7E-482E-BDDF-AE39F8856C97}"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Start Page="about:blank"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • HOMEOldSP="about:blank"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Search Bar="res://%User Temp%\sp.dll/sp.html"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Search Page="about:blank"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Use Search Asst="no"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
    • Use Custom Search URL="1"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Search
    • SearchAssistant="about:blank"
  • In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\New Windows
    • PopupMgr="no"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main
    • Start Page="about:blank"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main
    • HOMEOldSP="about:blank"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main
    • Search Bar="res://%User Temp%\sp.dll/sp.html"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main
    • Search Page="about:blank"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main
    • Use Search Asst="no"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main
    • Use Custom Search URL="1"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Search
    • SearchAssistant="about:blank"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\New Windows
    • PopupMgr="no"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\Classes\CLSID\{ED7893AD-F566-4702-B1E9-CE3201BDCD87}\InProcServer32
    • ThreadingModel="Apartment"

Step 5

Search and delete these files

[ Learn More ]
There may be some component 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.
  • %System%\miki.dll
  • %User Temp%\sp.dll
  • %System%\sqlppmo.dll

Step 6

Scan your computer with your Trend Micro product to delete files detected as TROJ_SMALL.GT. 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 7

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.

  • %Windows%\msn.hta
  • %System Root%\filter.log


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