Backdoor.Floodnet

[Randy_Bell]

Symantec Security Response - Backdoor.Floodnet

Backdoor.Floodnet is a backdoor Trojan that gives an attacker unauthorized access to the computer on which it is installed. By default it opens port 6969 on the infected computer. The Trojan attempts to disable some antivirus and firewall programs by terminating their active processes.

Also Known As: Backdoor.Floodnet [AVP]
Type: Trojan Horse
Infection Length: 102,400 bytes
Systems Affected: Windows 95, Windows 98, Windows NT, Windows 2000, Windows XP, Windows Me
Systems Not Affected: Windows 3.x, Macintosh, OS/2, Unix, Linux

technical details

When Backdoor.Floodnet runs, it performs the following actions:

It copies itself as %windir%\FLooDeR.exe.

NOTE: %windir% is a variable. The Trojan locates the Windows main installation folder (by default this is C:\Windows or C:\Winnt) and uses it as a destination folder.

The Trojan creates the value

FLooDNeT %windir%\FLooDeR.exe

in the registry key

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

so that the Trojan starts when you start or restart Windows.

The Trojan attempts to disable some antivirus and firewall programs by terminating their active processes.

It uses ICQ pager to notify the client side.

After Backdoor.Floodnet is installed, it waits for commands from the remote client. The commands allow the hacker to perform Denial of Service (DoS) attacks.

removal instructions

NOTE: These instructions are for all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

1. Update the virus definitions.
2. Do one of the following:
Windows 95/98/Millenium: Restart the computer in Safe mode.
Windows NT/2000/XP: End the Trojan process.
3. Run a full system scan, and delete all files that are detected as Backdoor.Floodnet.
4. Remove the value that the Trojan added to the registry key

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

To restart the computer in Safe mode or end the Trojan process:

Windows 95/98/Millenium
Restart the computer in Safe mode. All Windows 32-bit operating systems, except for Windows NT, can be restarted in Safe mode. For instructions on how to do this, read the document How to start the computer in Safe Mode.

Windows NT/2000/XP
To end the Trojan process:
1. Press Ctrl+Alt+Delete once.
2. Click Task Manager.
3. Click the Processes tab.
4. Double-click the Image Name column header to sort the processes alphabetically.
5. Scroll through the list, and look for FLooDeR.exe.
6. If you find the file, click it, and then click End Process.
7. Exit the Task Manager.

To reverse the changes that the Trojan made to the registry:

CAUTION: Symantec strongly recommends that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.

1. Click Start, and click Run. The Run dialog box appears.
2. Type regedit and then click OK. The Registry Editor opens.
3. Navigate to the key

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

4. In the right pane, delete the value

FLooDNeT %windir%\FLooDeR.exe

5. Exit the Registry Editor.

NOTE: You may need to reinstall your antivirus or firewall software.