Troj/Madr-B

Please follow the instructions for removing Trojans.

Windows NT/2000/XP/2003

In Windows NT/2000/XP/2003 you will also need to edit the following registry entries. The removal of these entries is optional in Windows 95/98/Me. 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 entry:

HKLM\Software\Microsoft\Windows\CurrentVersion\Run\
Winlogon = <WINDOWS>\system\winlogon.exe

and delete it if it exists.

Each user has a registry area named HKEY_USERS\[code number indicating user]\. For each user locate the entry:

HKU\[code number]\Software\Microsoft\Windows\
CurrentVersion\Run\Winlogon = <WINDOWS>\system32\wins\winlogon.exe

and delete it if it exists.

Close the registry editor and reboot your computer.

Troj/Madr-B is a backdoor Trojan which allows a remote intruder to access and control the computer via IRC channels.

When first run the Trojan copies itself as winlogon.exe to the folders <WINDOWS>\system\ and <WINDOWS>\system32\wins\ with the read-only and hidden attributes set and creates the following registry entries, so that winlogon.exe is run automatically each time Windows is started:

HKLM\Software\Microsoft\Windows\CurrentVersion\Run\
Winlogon = <WINDOWS>\system\winlogon.exe

HKCU\Software\Microsoft\Windows\CurrentVersion\Run\
Winlogon = <WINDOWS>\system32\wins\winlogon.exe

Each time the Trojan is run it tries to connect to a remote IRC server and join a specific channel using a random nickname. The Trojan then runs continuously in the background, listening on the channel for commands to execute.