TROJ_STARTPAGE.Y
Trojan:Win32/Startpage.Y (Microsoft), Trojan.Win32.StartPage.y (Kaspersky), Trojan.Bootconf (Symantec), StartPage-Q (McAfee), W32/Startpage.FL (Authentium), Trojan.StartPage.Y (Bitdefender), W32/StartPage.TH!tr (Fortinet), Trojan.Win32.StartPage (Ikarus), Win32/StartPage.NAB trojan (Eset), Trojan W32/Startpage_based.gen (Norman),
Windows 2000, Windows XP, Windows Server 2003
Threat Type: Trojan
Destructiveness: No
Encrypted: No
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.
It modifies the affected system's HOSTS files. This prevents users from accessing certain websites.
However, as of this writing, the said sites are inaccessible.
TECHNICAL DETAILS
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.
Installation
This Trojan drops the following files:
- %Windows%\Web\oslogo.bmp
(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)
Other System Modifications
This Trojan adds the following registry entries as part of its installation routine:
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer
Search = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387 "
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer
SearchURL = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387 "
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Search
SearchAssistant = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387 "
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Search
CustomizeSearch = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387 "
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Styles
User Stylesheet = "%Windows%\Web\oslogo.bmp"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Styles
Use My Stylesheet = "1"
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Default_Search_URL = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387 "
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Search Bar = "http://www.{BLOCKED}search.com/z/c/x1.cgi?656387 "
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
HOMEOldSP = "http://www.{BLOCKED}search.com/z/a/x1.cgi?656387 "
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Default_Page_URL = "http://www.{BLOCKED}search.com/z/a/x1.cgi?656387 "
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer
Search = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387 "
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Styles
User Stylesheet = "%Windows%\Web\oslogo.bmp"
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Styles
Use My Stylesheet = "1"
It modifies the following registry key(s)/entry(ies) as part of its installation routine:
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Start Page = "http://www.{BLOCKED}search.com/z/a/x1.cgi?656387 about:blank"
(Note: The default value data of the said registry entry is {default}.)
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Main
Search Page = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387 "
(Note: The default value data of the said registry entry is {default}.)
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Main
Default_Search_URL = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387 "
(Note: The default value data of the said registry entry is {default homepage}.)
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Main
Search Page = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387 "
(Note: The default value data of the said registry entry is {default homepage}.)
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Search
SearchAssistant = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387 "
(Note: The default value data of the said registry entry is {default}.)
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Internet Explorer\Search
CustomizeSearch = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387 "
(Note: The default value data of the said registry entry is {default}.)
It adds the following registry keys as part of its installation routine:
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Search
HKEY_CURRENT_USER\Software\Microsoft\
Internet Explorer\Styles
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
ZoneMap\Domains\{BLOCKED}search.com
HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Internet Settings\
ZoneMap\Domains\msn.com
HOSTS File Modification
This Trojan adds the following strings to the Windows HOSTS file:
- {random numbers} auto.search.msn.com
Other Details
However, as of this writing, the said sites are inaccessible.
SOLUTION
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
Delete this registry key
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_CURRENT_USER\Software\Microsoft\Internet Explorer
- Search
- Search
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer
- Styles
- Styles
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap\Domains
- {BLOCKED}search.com
- {BLOCKED}search.com
- In HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings\ZoneMap\Domains
- msn.com
- msn.com
Step 3
Delete this registry value
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\Internet Explorer
- Search = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
- Search = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer
- SearchURL = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
- SearchURL = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
- Default_Search_URL = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
- Default_Search_URL = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
- Search Bar = "http://www.{BLOCKED}search.com/z/c/x1.cgi?656387"
- Search Bar = "http://www.{BLOCKED}search.com/z/c/x1.cgi?656387"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
- HOMEOldSP = "http://www.{BLOCKED}search.com/z/a/x1.cgi?656387"
- HOMEOldSP = "http://www.{BLOCKED}search.com/z/a/x1.cgi?656387"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
- Default_Page_URL = "http://www.{BLOCKED}search.com/z/a/x1.cgi?656387"
- Default_Page_URL = "http://www.{BLOCKED}search.com/z/a/x1.cgi?656387"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer
- Search = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
- Search = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Styles
- User Stylesheet = "%Windows%\Web\oslogo.bmp"
- User Stylesheet = "%Windows%\Web\oslogo.bmp"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Styles
- Use My Stylesheet = "1"
- Use My Stylesheet = "1"
Step 4
Restore this modified registry value
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\Internet Explorer\Main
- From: Start Page = "http://www.{BLOCKED}search.com/z/a/x1.cgi?656387"
To: Start Page = {default}
- From: Start Page = "http://www.{BLOCKED}search.com/z/a/x1.cgi?656387"
- In HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Main
- From: Search Page = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
To: Search Page = {default}
- From: Search Page = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main
- From: Default_Search_URL = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
To: Default_Search_URL = {default homepage}
- From: Default_Search_URL = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Main
- From: Search Page = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
To: Search Page = {default homepage}
- From: Search Page = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Search
- From: SearchAssistant = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
To: SearchAssistant = {default}
- From: SearchAssistant = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
- In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer\Search
- From: CustomizeSearch = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
To: CustomizeSearch = {default}
- From: CustomizeSearch = "http://www.{BLOCKED}search.com/z/b/x1.cgi?656387"
Step 5
Remove these strings added by the malware/grayware/spyware in the HOSTS file
- {random numbers} auto.search.msn.com
Step 6
Search and delete this file
- %Windows%\Web\oslogo.bmp
Step 7
Scan your computer with your Trend Micro product to delete files detected as TROJ_STARTPAGE.Y. 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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