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WORM_FLASHY.AA

Overview

Malware type: Worm

Aliases: No Alias Found

In the wild: Yes

Destructive: No

Language: English

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

Encrypted: No

Overall risk rating:

Reported infections:

Damage potential:

High

Distribution potential:

Medium

Description: 

A worm is a malware that is designed to propagate and spread across networks. Worms are known to propagate using one or several of different transmission vectors like email, IRC, network shares, instant messengers (IM), and peer-to-peer (P2P) networks.

Worms do not infect files, but may carry one or more payloads, such as computer security compromise and information theft.

Worms typically modify system settings to automatically start. Users may need to terminate worms before they can be deleted. Also, restoring affected systems may require procedures other than scanning with an antivirus program.

For additional information about this threat, see:

Description created: Jun. 1, 2009 7:22:11 AM GMT -0800


Technical Details

File type: EXE

Memory resident:  Yes

Size of malware: 82,849 Bytes

Initial samples received on: Apr 16, 2009

Payload 1: Compromises system security

Payload 2: Disables certain Windows functionalities

Details:

Installation

This worm drops the following copy(ies) of itself:

  • %System%\Flashy.exe
  • %User Startup%\systemID.pif

(Note: %System% is the Windows system folder, which is usually C:\Windows\System on Windows 98 and ME, C:\WINNT\System32 on Windows NT and 2000, or C:\Windows\System32 on Windows XP and Server 2003. %User Startup% is the current user's Startup folder, which is usually C:\Documents and Settings\{user name}\Start Menu\Programs\Startup.)

Autostart Techniques

This worm creates the following registry entry(ies) to enable its automatic execution at every system startup:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
Windows\CurrentVersion\Run
Flashy Bot = "%System%\Flashy.exe"

Other System Modifications

This worm creates the following registry entry(ies) to disable Task Manager:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System\
DisableRegistryTools = "1"

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
System\
DisableTaskMgr = "1"

It modifies the following registry entry(ies) to hide files with both System and Read-only attributes:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
Hidden = "2"

(Note: The default value data for the said registry entry is 1.)

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Explorer\
Advanced
HideFileExt = "2"

(Note: The default value data for the said registry entry is 0.)

It creates the following registry key(s)/entry(ies) as part of its installation routine:

HKEY_CURRENT_USER\Software\Microsoft\
Windows\CurrentVersion\Policies\
Explorer
NoFolderOptions = "2"

Propagation via Physical/Removable/Floppy Drives

This worm drops copies of itself in all removable drives as FLASHY.EXE. It also searches for folders in removable drives then drop copies of itself as {FOLDER NAME}.EXE. It then hides the folders to trick users into clicking the malware copy.

Other Details

This worm uses an icon to trick users into thinking that it is a legitimate application.

It bears the normal Windows folder icon.

It creates the following mutex(es) to ensure that only one instance of itself is running in memory:

  • ||Flashy||

It opens a telnet session to enable a remote user to access the affected system.

Analysis By: Karl Dominguez


Solution

Minimum scan engine version needed: 8.700

Pattern file needed: 5.971.00

Pattern release date: Apr 16, 2009


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:

For Windows ME and XP users, before doing any scans, please make sure you disable System Restore to allow full scanning of your computer.

 Step 1: Restart in Safe Mode  [learn how]

 Step 2: Enable Registry Editor, Task Manager, and Folder Options  [learn how]

*Note: By doing this step, you also enable other applications/programs disabled by this malware/grayware/spyware.

 Step 3:  Delete this registry value  [learn how]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\
    Windows\CurrentVersion\Run
    • Flashy Bot = "%System%\Flashy.exe"

 Step 4:  Restore this modified registry value  [learn how]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

  • In HKEY_CURRENT_USER\Software\Microsoft\
    Windows\CurrentVersion\Explorer\
    Advanced
    • From: Hidden = "2"
      To: Hidden = "1"
    • From: HideFileExt = "2"
      To: HideFileExt = "0"

 Step 5: Scan your computer with your Trend Micro product to delete files detected as WORM_FLASHY.AA  

*Note: If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.




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