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BKDR_LONGNU.A

Malware type: Backdoor

Aliases: Backdoor.Win32.Logonui.b (Kaspersky), BackDoor-AFJ (McAfee), Trojan Horse (Symantec), TR/Logonui.B (Avira), Troj/Netcruz-B (Sophos),

In the wild: No

Destructive: No

Language: English

Platform: Windows 95,98,ME,NT,2000,XP

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

High

Distribution potential:

Low

Description: 

When run, this backdoor program opens a port then waits for an outside connection. Once a port is opened, the infected system becomes an easy target to malicious users who can connect and gain access to the system using Telnet or other similar programs which are used for remote connection.

It displays the following fake error message:

BKDR_LONGNU.A upon execution displays a fake error message box with the title Fatal Error and message - Error #251: Failed to init randomize

Then, it downloads the file, logonui32.bin, which is an updated copy of itself from the following sites:

  • http://www.geocities.com/haz<BLOCKED>lten/
  • http://www.geocities.com/pet<BLOCKED>r0xf0rd/
  • http://www.geocities.com/kks<BLOCKED>wnz/

This non-memory resident backdoor runs on Windows 95, 98, ME, NT, 2000, XP and is compiled using Visual Basic 6, a high-level programming language.

For additional information about this threat, see:

Description created: Mar. 22, 2003 4:17:53 AM GMT -0800
Description updated: Mar. 22, 2003 5:09:15 AM GMT -0800


Minimum scan engine version needed: 5.200

Pattern file needed: 1.493.23

Pattern release date: Mar 22, 2003


Important note: The "Minimum scan engine" refers to the earliest Trend Micro scan engine version guaranteed to detect this threat. However, Trend Micro strongly recommends that you update to the latest version in order to get comprehensive protection. Download the latest scan engine here.

Solution:

Identifying the Malware Program

Before proceeding to remove this malware, first identify the malware program.

Scan your system with Trend Micro antivirus and NOTE all files detected as . To do this, Trend Micro customers must download the latest pattern file and scan their system. Other Internet users can use HouseCall, Trend Micro's free online virus scanner.

Terminating the Malware Program

This procedure terminates the running malware process from memory. You will need the name(s) of the file(s) detected earlier.

  1. Open Windows Task Manager.
    On Windows 95/98/ME systems, press
    CTRL+ALT+DELETE
    On Windows NT/2000/XP systems, press
    CTRL+SHIFT+ESC, then click the Processes tab.
  2. In the list of running programs*, locate the malware file or files detected earlier.
  3. Select one of the detected files, then press either the End Task or the End Process button, depending on the version of Windows on your system.
  4. Do the same for all detected malware files in the list of running processes.
  5. To check if the malware process has been terminated, close Task Manager, and then open it again.
  6. Close Task Manager.

*NOTE: On systems running Windows 95/98/ME, Task Manager may not show certain processes. You may use a third party process viewer to terminate the malware process. Otherwise, continue with the next procedure, noting additional instructions.

Removing Autostart Entries from the Registry

Removing autostart entries from the registry prevents the malware from executing during startup.

  1. Open Registry Editor. To do this, click Start>Run, type Regedit, then press Enter.
  2. In the left panel, double-click the following:
    HKEY_LOCAL_MACHINE>Software>Microsoft>
    Windows>CurrentVersion>Run
  3. In the right panel, locate and delete the entry or entries:
    loginui32 = "%Windows%\loginui32.exe"
    Note: %Windows% is the default Windows folder, usually C:\Windows or C:\WinNT.
  4. Close Registry Editor.
NOTE: If you were not able to terminate the malware process from memory as described in the previous procedure, restart your system.

Deleting Dropped Files

On Windows 9x/NT

  1. Click Start>Find>Files and Folders.
  2. In the Named input box, type:
  3. In the Look In drop-down list, select the drive which contains Windows, then press Enter.
On Windows 2000/ME/XP
  1. Click Start>Search>For Files and Folders.
  2. In the Search for files and folders named input box, type:
  3. In the Look In drop-down list, select the drive which contains Windows, then press Enter.

Once found, manually delete the file.

Running Trend Micro Antivirus

Scan your system with Trend Micro antivirus and clean all files detected as BKDR_LONGNU.A. To do this, Trend Micro customers must download the latest pattern file and scan their system. Other Internet users can use HouseCall, Trend Micros free online virus scanner.


Trend Micro offers best-of-breed antivirus and content-security solutions for your corporate network, small and medium business, mobile device or home PC.