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.
O6 - IE Options access restricted by Administrator
What it looks like:
O6 - HKCU\Software\Policies\Microsoft\Internet Explorer\Restrictions present
What to do:
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.
O7 - Regedit access restricted by Administrator
What it looks like:
O7 - HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System, DisableRegedit=1
What to do:
Always have HijackThis fix this, unless your system administrator has put this restriction into place.
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.
O9 - Extra buttons on main IE toolbar, or extra items in IE 'Tools' menu
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.
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, or Spybot S&D from Kolla.de.
Note that 'unknown' files in the LSP stack will not be fixed by HijackThis, for safety issues.
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.
O12 - IE plugins
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).
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:
These are always bad. Have HijackThis fix them.
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.
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.
O16 - ActiveX Objects (aka Downloaded 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 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.
Javacool's SpywareBlaster has a huge database of malicious ActiveX objects that can be used for looking up CLSIDs. (Right-click the list to use the Find function.)