W32/Agobot-OS

Please follow the instructions for removing worms.

Check your administrator passwords and review network security.

Replace the Hosts file from a backup or edit it in Notepad to remove the changes that the worm has made.

You will also need to edit the following registry entries, if they are present. Please read the warning about editing the registry.

At the taskbar, click Start|Run. Type 'Regedit' and press Return. The registry editor opens.

Before you edit the registry, you should make a backup. On the 'Registry' menu, click 'Export Registry File'. In the 'Export range' panel, click 'All', then save your registry as Backup.

Locate the HKEY_LOCAL_MACHINE entries:

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Fenio Startups
fnesvc32.exe

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices
Fenio Startups
fnesvc32.exe

and delete them if they exist.

Close the registry editor.

W32/Agobot-OS is an IRC backdoor Trojan and network worm.

W32/Agobot-OS is capable of spreading to computers on the local network protected by weak passwords.

When first run, W32/Agobot-OS copies itself to the Windows system folder as fnesvc32.exe and creates the following registry entries to run itself each time a user logs on:

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
Fenio Startups
fnesvc32.exe

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices
Fenio Startups
fnesvc32.exe

The backdoor component runs continuously in the background providing backdoor access to the computer through IRC channels.

W32/Agobot-OS attempts to terminate and disable various anti-virus and security related programs and modifies the HOSTS file located at %SYSTEM%\Drivers\etc\HOSTS, mapping selected anti-virus websites to the loopback address 127.0.0.1 in an attempt to prevent access to these sites. Typically the following mappings will be appended to the HOSTS file:

127.0.0.1 www.symantec.com
127.0.0.1 securityresponse.symantec.com
127.0.0.1 symantec.com
127.0.0.1 www.sophos.com
127.0.0.1 sophos.com
127.0.0.1 www.mcafee.com
127.0.0.1 mcafee.com
127.0.0.1 liveupdate.symantecliveupdate.com
127.0.0.1 www.viruslist.com
127.0.0.1 viruslist.com
127.0.0.1 viruslist.com
127.0.0.1 f-secure.com
127.0.0.1 www.f-secure.com
127.0.0.1 kaspersky.com
127.0.0.1 www.avp.com
127.0.0.1 www.kaspersky.com
127.0.0.1 avp.com
127.0.0.1 www.networkassociates.com
127.0.0.1 networkassociates.com
127.0.0.1 www.ca.com
127.0.0.1 ca.com
127.0.0.1 mast.mcafee.com
127.0.0.1 my-etrust.com
127.0.0.1 www.my-etrust.com
127.0.0.1 download.mcafee.com
127.0.0.1 dispatch.mcafee.com
127.0.0.1 secure.nai.com
127.0.0.1 nai.com
127.0.0.1 www.nai.com
127.0.0.1 update.symantec.com
127.0.0.1 updates.symantec.com
127.0.0.1 us.mcafee.com
127.0.0.1 liveupdate.symantec.com
127.0.0.1 customer.symantec.com
127.0.0.1 rads.mcafee.com
127.0.0.1 trendmicro.com
127.0.0.1 www.trendmicro.com

W32/Agobot-OS will also hide all files which contain the string 'soun'.

Sophos's anti-virus products include proactive protection technology, which can defend against new threats without requiring an update. Sophos customers have been protected against W32/Agobot-OS (detected as W32/Agobot-Gen) since version 3.86.