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HijackThis Log Tutorial
Based on the original tutorial by Merijn Bellekom (Copyright © All rights reserved). Adapted with permission of the author.
AumHa.org customization last updated by James A. Eshelman March 2, 2009 E.V.

On the AumHa Forums and many other support Web sites, a lot of people new to browser hijacking post topics asking for help analyzing logs from HijackThis, because they don’t understand what stuff is good and what is bad. This is a basic guide as to what the log means, and some tips on reading it yourself.


OVERVIEW

Each line in a HijackThis log starts with a section name. (For technical information on this, click ‘Info’ in the main window and scroll down. Highlight a line and click ‘More info on this item’.) For practical information, click the section name you need help with:

R0, R1, R2, R3 - IE Start & Search pages

What it looks like:

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.google.com/
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://www.google.com/
R2 - (this type is not used by HijackThis yet)
R3 - Default URLSearchHook is missing

What are these?
R0 items are changed Registry values.
R1 items are created Registry values.
R2 items are created Registry keys.
R3 items are created extra Registry values where only one should exist.

What to do:
If you recognize the URL at the end as your homepage or search engine, it’s OK. If you don’t, check it and have HijackThis fix it.
For the R3 items, always fix them unless it mentions a program you recognize, like Copernic.

[Need more details? Check the R0, R1, R2, R3 help on BleepingComputer.com. – Mr. E.]

F0, F1, F2, F3 - Autoloading programs from INI files

What it looks like:

F0 - system.ini: Shell=Explorer.exe Openme.exe
F1 - win.ini: run=hpfsched

What are these?
F0 items are changed INI file values.
F1 items are created INI file values.
F2 items are changed INI file values mapped to the Registry.
F3 items are created INI file values mapped to the Registry.

What to do:
The F0 items are always bad, so fix them.
The F1 items are usually very old programs that are safe, so you should find some more info on the filename to see if it’s good or bad.
Pacman’s Startup List can help with identifying an item. [If that site is down, try these alternatives: Windows Startup Online Repository (based on PacMan’s site); AnswersThatWork; and Kephyr’s File Database; or download the current offline copy from PacMan. – Mr. E.]

[Need more details? Check the F0, F1, F2, F3 help on BleepingComputer.com. – Mr. E.]

N1, N2, N3, N4 - Netscape/Mozilla Start & Search page

What it looks like:

N1 - Netscape 4: user_pref("browser.startup.homepage", "www.google.com"); (C:\Program Files\Netscape\Users\default\prefs.js)
N2 - Netscape 6: user_pref("browser.startup.homepage", "http://www.google.com"); (C:\Documents and Settings\User\Application Data\Mozilla\Profiles\defaulto9t1tfl.slt\prefs.js)
N2 - Netscape 6: user_pref("browser.search.defaultengine", "engine://C%3A%5CProgram%20Files%5CNetscape%206%5Csearchplugins%5CSBWeb_02.src"); (C:\Documents and Settings\User\Application Data\Mozilla\Profiles\defaulto9t1tfl.slt\prefs.js)

What are these?
N0 items are changes in prefs.js of Netscape 4.x.
N1 items are changes in prefs.js of Netscape 6.
N2 items are changes in prefs.js of Netscape 7.
N3 items are changes in prefs.js of Mozilla.

What to do:
Usually the Netscape and Mozilla homepage and search page are safe. They rarely get hijacked, only Lop.com has been known to do this. Should you see an URL you don’t recognize as your homepage or search page, have HijackThis fix it.

Specifically, N1 indicates pref.js changes in Netscape 4.x, N2 in Netscape 6, N3 in Netscape 7, and N4 in Mozilla.

[Need more details? Check the N1, N2, N3, N4 help on BleepingComputer.com. – Mr. E.]

O1 - Hostsfile redirections

What it looks like:

O1 - Hosts: 216.177.73.139 auto.search.msn.com
O1 - Hosts: 216.177.73.139 search.netscape.com
O1 - Hosts: 216.177.73.139 ieautosearch
O1 - Hosts file is located at C:\Windows\Help\hosts

What to do:
This hijack will redirect the address to the right to the IP address to the left. If the IP does not belong to the address, you will be redirected to a wrong site everytime you enter the address. You can always have HijackThis fix these, unless you knowingly put those lines in your Hosts file.
The last item sometimes occurs on Windows 2000/XP with a Coolwebsearch infection. Always fix this item, or have CWShredder repair it automatically.

[Need more details? Check the O1 help on BleepingComputer.com. – Mr. E.]

O2 - Browser Helper Objects (BHOs)

What it looks like:

O2 - BHO: Yahoo! Companion BHO - {13F537F0-AF09-11d6-9029-0002B31F9E59} - C:\PROGRAM FILES\YAHOO!\COMPANION\YCOMP5_0_2_4.DLL
O2 - BHO: (no name) - {1A214F62-47A7-4CA3-9D00-95A3965A8B4A} - C:\PROGRAM FILES\POPUP ELIMINATOR\AUTODISPLAY401.DLL (file missing)
O2 - BHO: MediaLoads Enhanced - {85A702BA-EA8F-4B83-AA07-07A5186ACD7E} - C:\PROGRAM FILES\MEDIALOADS ENHANCED\ME1.DLL

What to do:
If you don’t directly recognize a Browser Helper Object’s name, use TonyK’s BHO & Toolbar List to find it by the class ID (CLSID, the number between curly brackets) and see if it’s good or bad. In the BHO List, ‘X’ means spyware and ‘L’ means safe. If that site is down, a different version of the same list can be found on SysInfo.org.

[Need more details? Check the O2 help on BleepingComputer.com. – Mr. E.]

O3 - IE toolbars

What it looks like:

O3 - Toolbar: &Yahoo! Companion - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - C:\PROGRAM FILES\YAHOO!\COMPANION\YCOMP5_0_2_4.DLL
O3 - Toolbar: Popup Eliminator - {86BCA93E-457B-4054-AFB0-E428DA1563E1} - C:\PROGRAM FILES\POPUP ELIMINATOR\PETOOLBAR401.DLL (file missing)
O3 - Toolbar: rzillcgthjx - {5996aaf3-5c08-44a9-ac12-1843fd03df0a} - C:\WINDOWS\APPLICATION DATA\CKSTPRLLNQUL.DLL

What to do:
If you don’t directly recognize a Browser Helper Object’s name, use TonyK’s BHO & Toolbar List to find it by the class ID (CLSID, the number between curly brackets) and see if it’s good or bad. In the BHO List, ‘X’ means spyware and ‘L’ means safe. If that site is down, a different version of the same list can be found on SysInfo.org.

If it’s not on the list and the name seems a random string of characters and the file is in the ‘Application Data’ folder (like the last one in the examples above), it’s probably Lop.com, and you definately should have HijackThis fix it.

[Need more details? Check the O3 help on BleepingComputer.com. – Mr. E.]

O4 - Autoloading programs from Registry or Startup group

What it looks like:

O4 - HKLM\..\Run: [ScanRegistry] C:\WINDOWS\scanregw.exe /autorun
O4 - HKLM\..\Run: [SystemTray] SysTray.Exe
O4 - HKLM\..\Run: [ccApp] "C:\Program Files\Common Files\Symantec Shared\ccApp.exe"
O4 - Startup: Microsoft Office.lnk = C:\Program Files\Microsoft Office\Office\OSA9.EXE
O4 - Global Startup: winlogon.exe

What to do:
Use one of the following references (or Google) to find the entry and see if it’s good or bad: Kephyr’s File Database; Windows Startup Online Repository (also based on PacMan’s site); and AnswersThatWork; or download the current offline copy from PacMan. – Mr. E.]
If the item shows a program sitting in a Startup group (like the last item above), HijackThis cannot fix the item if this program is still in memory. Use the Windows Task Manager (TASKMGR.EXE) to close the process prior to fixing.

[Need more details? Check the O4 help on BleepingComputer.com. – Mr. E.]

O5 - IE Options not visible in Control Panel

What it looks like:

O5 - control.ini: inetcpl.cpl=no

What to do:
Unless you or your system administrator have knowingly hidden the icon from Control Panel, have HijackThis fix it.

[Need more details? Check the O5 help on BleepingComputer.com. – Mr. E.]

O6 - IE Options access restricted by Administrator

What it looks like:

O6 - HKCU\Software\Policies\Microsoft\Internet Explorer\Restrictions present

What to do:
These items depict the disabling of Internet Options ‘Main’ tab via Policy controls. Unless you have the Spybot S&D option ‘Lock homepage from changes’ active, or your system administrator put this into place, have HijackThis fix this.

[Need more details? Check the O6 help on BleepingComputer.com. – Mr. E.]

O7 - Regedit access restricted by Administrator

What it looks like:

O7 - HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System, DisableRegedit=1

What to do:
These items depict the disabling of RegEdit via Policy controls. Always have HijackThis fix this, unless your system administrator has put this restriction into place.

[Need more details? Check the O7 help on BleepingComputer.com. – Mr. E.]

O8 - Extra items in IE right-click menu

What it looks like:

O8 - Extra context menu item: &Google Search - res://C:\WINDOWS\DOWNLOADED PROGRAM FILES\GOOGLETOOLBAR_EN_1.1.68-DELEON.DLL/cmsearch.html
O8 - Extra context menu item: Yahoo! Search - file:///C:\Program Files\Yahoo!\Common/ycsrch.htm
O8 - Extra context menu item: Zoom &In - C:\WINDOWS\WEB\zoomin.htm
O8 - Extra context menu item: Zoom O&ut - C:\WINDOWS\WEB\zoomout.htm

What to do:
If you don’t recognize the name of the item in the right-click menu in IE, have HijackThis fix it.

[Need more details? Check the O8 help on BleepingComputer.com. – Mr. E.]

O9 - Extra buttons on main IE toolbar, or extra menu items

What it looks like:

O9 - Extra button: Messenger (HKLM)
O9 - Extra ‘Tools’ menuitem: Messenger (HKLM)
O9 - Extra button: AIM (HKLM)

What to do:
If you don’t recognize the name of the button or menuitem, have HijackThis fix it.

[Need more details? Check the O9 help on BleepingComputer.com. – Mr. E.]

O10 - Winsock hijackers

What it looks like:

O10 - Hijacked Internet access by New.Net
O10 - Broken Internet access because of LSP provider ‘c:\progra~1\common~2\toolbar\cnmib.dll’ missing
O10 - Unknown file in Winsock LSP: c:\program files\newton knows\vmain.dll

What to do:
It’s best to fix these using LSPFix from Cexx.org.
[In Windows XP SP2, the command netsh winsock reset reportedly will fix this without the need of LSPFix. – Mr. E.]
Note that ‘unknown’ files in the LSP stack will not be fixed by HijackThis, for safety issues.

[Need more details? Check the O10 help on BleepingComputer.com. – Mr. E.]

O11 - Extra group in IE ‘Advanced Options’ window

What it looks like:

O11 - Options group: [CommonName] CommonName

What to do:
The only hijacker as of now that adds its own options group to the IE Advanced Options window is CommonName. So you can always have HijackThis fix this.

[Need more details? Check the O11 help on BleepingComputer.com. – Mr. E.]

O12 - IE plugins for file extensions or MIME types

What it looks like:

O12 - Plugin for .spop: C:\Program Files\Internet Explorer\Plugins\NPDocBox.dll
O12 - Plugin for .PDF: C:\Program Files\Internet Explorer\PLUGINS\nppdf32.dll

What to do:
Most of the time these are safe. Only OnFlow adds a plugin here that you don’t want (.ofb).

[Need more details? Check the O12 help on BleepingComputer.com. – Mr. E.]

O13 - IE DefaultPrefix hijack

What it looks like:

O13 - DefaultPrefix: http://www.pixpox.com/cgi-bin/click.pl?url=
O13 - WWW Prefix: http://prolivation.com/cgi-bin/r.cgi?
O13 - WWW. Prefix: http://ehttp.cc/?

What to do:
This shows changes made in how Windows interprets URLs entered without a preceding http:// etc. One tactic of some malware is to change these as a form of browser redirection. These are always bad unless you have knowingly made a change in browser behavior. Have HijackThis fix any changes that you didn’t make.

[Need more details? Check the O13 help on BleepingComputer.com. – Mr. E.]

O14 - ‘Reset Web Settings’ hijack

What it looks like:

O14 - IERESET.INF: START_PAGE_URL=http://www.searchalot.com

What to do:
If the URL is not the provider of your computer or your ISP, have HijackThis fix it.

[Need more details? Check the O14 help on BleepingComputer.com. – Mr. E.]

O15 - Unwanted sites in Trusted Zone

What it looks like:

O15 - Trusted Zone: http://free.aol.com
O15 - Trusted Zone: *.coolwebsearch.com
O15 - Trusted Zone: *.msn.com

What to do:
Most of the time only AOL and Coolwebsearch silently add sites to the Trusted Zone. If you didn’t add the listed domain to the Trusted Zone yourself, have HijackThis fix it.

[Need more details? Check the O15 help on BleepingComputer.com. – Mr. E.]

O16 - ActiveX Objects (aka Downloaded ActiveX Program Files)

What it looks like:

O16 - DPF: Yahoo! Chat - http://us.chat1.yimg.com/us.yimg.com/i/chat/applet/c381/chat.cab
O16 - DPF: {D27CDB6E-AE6D-11CF-96B8-444553540000} (Shockwave Flash Object) - http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab

What to do:
If you don’t directly recognize the name of the ActiveX object, start with Google to learn something about it.

In general, if you don’t recognize the name of the object, or the URL it was downloaded from, have HijackThis fix it. If the name or URL contains words like ‘dialer’, ‘casino’, ‘free_plugin’ etc, definitely fix it.

[Need more details? Check the O16 help on BleepingComputer.com. – Mr. E.]

O17 - Lop.com domain hijacks

What it looks like:

O17 - HKLM\System\CCS\Services\VxD\MSTCP: Domain = aoldsl.net
O17 - HKLM\System\CCS\Services\Tcpip\Parameters: Domain = W21944.find-quick.com
O17 - HKLM\Software\..\Telephony: DomainName = W21944.find-quick.com
O17 - HKLM\System\CCS\Services\Tcpip\..\{D196AB38-4D1F-45C1-9108-46D367F19F7E}: Domain = W21944.find-quick.com
O17 - HKLM\System\CS1\Services\Tcpip\Parameters: SearchList = gla.ac.uk
O17 - HKLM\System\CS1\Services\VxD\MSTCP: NameServer = 69.57.146.14,69.57.147.175

What to do:
If the domain is not from your ISP or company network, have HijackThis fix it. The same goes for the ‘SearchList’ entries.
For the ‘NameServer’ (DNS servers) entries, Google for the IP or IPs and it will be easy to see if they are good or bad.

[Need more details? Check the O17 help on BleepingComputer.com. – Mr. E.]

O18 - Extra protocols and protocol hijackers

What it looks like:

O18 - Protocol: relatedlinks - {5AB65DD4-01FB-44D5-9537-3767AB80F790} - C:\PROGRA~1\COMMON~1\MSIETS\msielink.dll
O18 - Protocol: mctp - {d7b95390-b1c5-11d0-b111-0080c712fe82}
O18 - Protocol hijack: http - {66993893-61B8-47DC-B10D-21E0C86DD9C8}

What to do:
If you don’t directly recognize an O18 item, start with Google to learn something about it. Only a few hijackers show up here, such as ‘cn’ (CommonName), ‘ayb’ (Lop.com) and ‘relatedlinks’ (Huntbar), you should have HijackThis fix those.
Other things that show up as O18 in HijackThis are either not confirmed safe yet, or are hijacked (i.e. the CLSID has been changed) by spyware. In the last case, have HijackThis fix it.

[Need more details? Check the O18 help on BleepingComputer.com. – Mr. E.]

O19 - User style sheet hijack

What it looks like:

O19 - User style sheet: c:\WINDOWS\Java\my.css

What to do:
In the case of a browser slowdown and frequent popups, have HijackThis fix this item if it shows up in the log. However, since only Coolwebsearch does this, it’s better to use CWShredder to fix it.

[Need more details? Check the O19 help on BleepingComputer.com. – Mr. E.]

O20 - AppInit_DLLs Registry value autorun

What it looks like:

O20 - AppInit_DLLs: msconfd.dll

What to do:
If you don’t directly recognize a DLL’s name, start with Google to learn something about it.

Further Information: This Registry value located at HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Windows loads a DLL into memory when the user logs in, after which it stays in memory until logoff. Very few legitimate programs use it (Norton CleanSweep uses APITRAP.DLL), most often it is used by trojans or agressive browser hijackers.
In case of a ‘hidden’ DLL loading from this Registry value (only visible when using ‘Edit Binary Data’ option in Regedit) the dll name may be prefixed with a pipe ‘|’ to make it visible in the log.

[Need more details? Check the O20 help on BleepingComputer.com. – Mr. E.]

O21 - ShellServiceObjectDelayLoad (SSODL) autorun

What it looks like:

O21 - SSODL - AUHOOK - {11566B38-955B-4549-930F-7B7482668782} - C:\WINDOWS\System\auhook.dll

What to do:
If you don’t directly recognize an O21 item, start with Google to learn something about it.

ShellServiceObjectDelayLoad is an undocumented autorun method, normally used by a few Windows system components. Items listed at HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\ShellServiceObjectDelayLoad are loaded by Explorer when Windows starts. HijackThis uses a whitelist of several very common SSODL items, so whenever an item is displayed in the log it is unknown and possibly malicious. Treat with extreme care.

[Need more details? Check the O21 help on BleepingComputer.com. – Mr. E.]

O22 - SharedTaskScheduler autorun

What it looks like:

O22 - SharedTaskScheduler: (no name) - {3F143C3A-1457-6CCA-03A7-7AA23B61E40F} - c:\windows\system32\mtwirl32.dll

What to do:
If you don’t directly recognize an O22 item, start with Google to learn something about it.

Shared Task Scheduler is an undocumented autorun for Windows NT/2000/XP only, which is used very rarely. So far only CWS.Smartfinder uses it. Treat with care.

[Need more details? Check the O22 help on BleepingComputer.com. – Mr. E.]

O23 - Services

What it looks like:

O23 - Service: Ati HotKey Poller - Unknown - C:\WINDOWS\System32\Ati2evxx.exe
O23 - Service: WZCBDL Service - D-Link - F:\Program Files\WZCBDL Service\WZCBDLS.exe

What to do:
This is the listing of non-Microsoft services. The list should be the same as the one you see in the MSCONFIG utility of Windows XP. If you don’t directly recognize an O23 item, start with Google to learn something about it.

Several Trojan hijackers use a homemade service in addition to other startups to reinstall themselves. The full name is usually important-sounding, like “Network Security Service,” “Workstation Logon Service,” or “Remote Procedure Call Helper,” but the internal name (between brackets) is a string of garbage, like 'O?rtȲ$'. The second part of the line is the owner of the file at the end, as seen in the file’s properties. NOTE: Fixing an O23 item will only stop the service and disable it. The service needs to be deleted from the Registry manually or with another tool. In HijackThis 1.99.1 or higher, the button “Delete NT Service” in the Misc Tools section can be used for this.

“Services” in Windows NT 4, Windows 2000, Windows XP, and Windows Server 2003 are a special type of program essential to the system and required for proper system functioning. Service processes are started before the user logs in and are protected by Windows. They can only be stopped from the Services dialogue in the Administrative Tools window (or from a Run box, just type SERVICES.MSC). Accordingly, malware that registers itself as a service is subsequently also harder to kill.

One useful site for checking out individual services is the Windows 2000 Services Tweak guide.

O24 - ActiveX Desktop Components

What it looks like:

O24 - Desktop Component 0: (Security) - %windir%\index.html
O24 - Desktop Component 1: (no name) - %Windir%\warnhp.html

What to do:
These are embedded Active Desktop items. Have HijackThis remove any that you don’t recognize.

[Need more details? Check the O24 help on BleepingComputer.com. – Mr. E.]


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