TROJ_DONBOMB.A

Malware type: Trojan

Aliases: SpamTool.Win32.Delf.h (Kaspersky), Spam-SPM (McAfee), Trojan.Spexta (Symantec), TR/Londrop (Avira), Troj/Spexta-A (Sophos),

In the wild: Yes

Destructive: No

Language: English

Platform: Windows 95, 98, ME, NT, 2000, XP, Server 2003

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

High

Distribution potential:

Low

Description: 

To get a one glance comprehensive view of the behavior of this worm, refer to the Behavior Diagram shown below.

TROJ_DONBOMB.A Behavior Diagram

Malware Description

This Trojan may arrive on an affected system as an attachment of an email message. Upon execution, it drops and executes a copy of itself in the Windows folder. The dropped file uses any of various predetermined file names. It then modifies the system registry to ensure its automatic execution at every system startup.

This Trojan then checks certain registry keys to obtain valuable information, such as user names and the Simple Mail Transfer Protocol (SMTP) servers used by the affected system.

It arrives via an email that uses the London bombing incident to trick users into opening and executing this Trojan.

The email has the following details:

Subject:
TERROR HITS LONDON

From:
"CNN Newsletter" {breakingnews@cnnonline.com}

Message body:
{A modified HTML copy of the CNN web page regarding the London Bombing}

Attachment:
LondonTerrorMovie.zip

(containing the following file)
London Terror Moovie.avi - multiple spaces
Checked By Norton Antivirus.exe

Below is a screenshot of the email:

TROJ_DONBOMB.A’s sample email

This Trojan also has the capacity to send out unsolicited email messages in bulk.

This Trojan generates email addresses by using certain strings appended with a domain name.

For additional information about this threat, see:

Description created: Jul. 9, 2005 5:27:10 AM GMT -0800


TECHNICAL DETAILS


File type: PE

Memory resident:  Yes

Size of malware: 82,432 Bytes (compressed); 206,848 Bytes (uncompressed)

Initial samples received on: Jul 8, 2005

Payload 1: Sends out bulk unsolicited mail

Details:

Installation and Autostart Technique

This memory-resident Trojan may arrive on an affected system as an attachment to email messages. Upon execution, it drops and executes a copy of itself in the Windows folder using any of the following file names:

  • ctflog.exe
  • explore.exe
  • inetinfomon.exe
  • MPM.exe
  • service.exe
  • winlog.exe

The dropped file uses the hidden attribute to avoid easy detection. This Trojan then creates any of the following registry entries to ensure its automatic execution at every Windows startup:

HKEY_LOCAL_MACHINE\Software\Microsoft\
Windows\CurrentVersion\Run
{any of the dropped file names without EXE extension} manager
= "%Windows%\{any of the dropped file names}"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Run
{any of the dropped file names without EXE extension} manager
= "%Windows%\{any of the dropped file names}"

(Note: %Windows% is the Windows folder, which is usually C:\Windows or C:\WINNT.)

Email Spamming

This Trojan checks the following registry keys to obtain user information, such as user accounts and the Simple Mail Transfer Protocol (SMTP) servers used by the affected system.

HKEY_CURRENT_USER\Software\Microsoft\
Internet Account Manager\Accounts

HKEY_CURRENT_USER\Software\Microsoft\
Office\Outlook\OMI Account Manager\Accounts

HKEY_CURRENT_USER\Software\Qualcomm\
Eudora\CommandLine\current

Documents and Settings\{User name}\Application Data\
Mozilla\Profiles\default

It generates email addresses by using any of the following strings appended with a domain name, which it copies from harvested email addresses:

  • about
  • abrupt
  • acetic
  • actinolite
  • Alana
  • Alexandria
  • Alvarado
  • anarch
  • apocryphal
  • blacksmith
  • blown
  • bolometer
  • Caldwell
  • Carlos
  • Carson
  • codfish
  • crystallite
  • Cummings
  • Curtis
  • dairymen
  • David
  • deducible
  • detour
  • diffusible
  • diurnal
  • Edward
  • Ellis
  • Fernandez
  • french
  • frostbite
  • Hillary
  • Hudson
  • hydrochemistry
  • Jimenez
  • Kenneth
  • loretta
  • Luisa
  • mail-hub
  • mail-relay
  • Malinda
  • Martinez
  • Mccoy
  • Mckinney
  • mentor
  • Oliver
  • reactionary
  • relay
  • relay
  • relay1
  • relay2
  • Ronald
  • Scott
  • Sharp
  • slovakia
  • Thomas
  • Torres
  • Victor
  • Wagner
  • Walton
  • Williams
  • wooden

It may also use the following domain names:

  • aol.com
  • msn.com
  • yahoo.com

It uses its gathered email addresses to send out unsolicited mail in bulk.

Email Arrival

This Trojan arrives via an email message that has the following details:

Subject:
TERROR HITS LONDON

From:
"CNN Newsletter" {breakingnews@cnnonline.com}

Message body:
{A modified HTML copy of the CNN web page regarding the London Bombing}

Attachment:
LondonTerrorMovie.zip

(containing the following file)
London Terror Moovie.avi {multiple spaces}
Checked By Norton Antivirus.exe

Below is a screenshot of the email that this Trojan arrives in:

TROJ_DONBOMB.A’s sample email

Other Details

This Trojan runs on Windows 95, 98, ME, NT, 2000, XP, and Server 2003. It also checks for the presence of the mutex "" to prevent multiple copies of itself from running in memory.

Analysis By: Roddell Aquino Santos

Revision History:

 
Jul 9, 2005 - Modified Virus Report

SOLUTION


Minimum scan engine version needed: 6.810

Pattern file needed: 2.720.07

Pattern release date: Jul 8, 2005


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

To remove this malware, first identify the malware program.

  1. Scan your system with your Trend Micro antivirus product.
  2. NOTE the path and file name of all files detected as TROJ_DONBOMB.A.

Trend Micro customers need to download the latest virus pattern file before scanning their system. Other users can use Housecall, Trend Micro's online virus scanner.

Terminating the Malware Program

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

  1. Open Windows Task Manager.
    • On Windows 98 and ME, press
    CTRL%20ALT%20DELETE
    • On Windows NT, 2000, XP, and Server 2003, press
    CTRL%20SHIFT%20ESC, then click the Processes tab.
  2. In the list of running programs*, locate the malware file(s) 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 98 and ME, Windows Task Manager may not show certain processes. You can use a third party process viewer such as Process Explorer to terminate the malware process. Otherwise, continue with the next procedure, noting additional instructions. If you were not able to terminate the malware process as described in the previous procedure, restart your system.

Editing the Registry

This malware modifies the system's registry. Users affected by this malware may need to modify or delete specific registry keys or entries. For detailed information regarding registry editing, please refer to the following articles from Microsoft:

  1. HOW TO: Backup, Edit, and Restore the Registry in Windows 98 and Windows ME
  2. HOW TO: Backup, Edit, and Restore the Registry in Windows NT 4.0
  3. HOW TO: Backup, Edit, and Restore the Registry in Windows 2000
  4. HOW TO: Back Up, Edit, and Restore the Registry in Windows XP and 2003

Removing Autostart Entries from the Registry

Removing autostart entries from the registry prevents the malware from executing at startup. In this procedure, you will need the name(s) of the file(s) detected earlier.

If the registry entries below are not found, the malware may not have executed as of detection. If so, proceed to the succeeding solution set.

  1. Open Registry Editor. 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 whose data value is the malware path and file name of the file(s) detected earlier.
  4. Again in the left panel, double-click the following:
    HKEY_CURRENT_USER>Software>Microsoft>
    Windows>CurrentVersion>Run
  5. In the right panel, locate and delete the entry or entries whose data value is the malware path and file name of the file(s) detected earlier.
  6. Close Registry Editor.

Important Windows ME/XP Cleaning Instructions

Users running Windows ME and XP must disable System Restore to allow full scanning of infected systems.

Users running other Windows versions can proceed with the succeeding procedure set(s).

Running Trend Micro Antivirus

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




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