Threat Description

Gibe

Details

Aliases: Gibe, I-Worm.Gibe, W32,Gibe@mm, W32/Gibe.A@mm
Category: Malware
Type: Worm
Platform: W32

Summary



Gibe is a mass-mailing worm written in Visual Basic. It disguises itself as a Microsoft security update.



Removal



Automatic Disinfection

Allow F-Secure Anti-Virus to disinfect the relevant files.

For more general information on disinfection, please see Removal Instructions.



Technical Details



The worm usually arrives as an attachment named Q216309.exe to the following message:

From: Microsoft Corporation Security Center
 mailto:rdquest12@microsoft.com]
 To: Microsoft Customer
 Subject: Internet Security Update
 Attachment: q216309.exe
 Microsoft Customer,
 this is the latest version of security update, the update which
 eliminates all known security vulnerabilities affecting Internet
 Explorer and MS Outlook/Express as well as six new
 vulnerabilities, and is discussed in Microsoft Security Bulletin
 MS02-005. Install now to protect your computer from these
 vulnerabilities, the most serious of which could allow an
 attacker to run code on your computer.
 Description of several well-know vulnerabilities:
 - "Incorrect MIME Header Can Cause IE to Execute E-mail
 Attachment" vulnerability. If a malicious user sends an affected
 HTML e-mail or hosts an affected e-mail on a Web site, and a
 user opens the e-mail or visits the Web site, Internet Explorer
 automatically runs the executable on the user's computer.
 - A vulnerability that could allow an unauthorized user to learn
 the location of cached content on your computer. This could
 enable the unauthorized user to launch compiled HTML Help (.chm)
 files that contain shortcuts to executables, thereby enabling
 the unauthorized user to run the executables on your computer.
 - A new variant of the "Frame Domain Verification" vulnerability
 could enable a malicious Web site operator to open two browser
 windows, one in the Web site's domain and the other on your
 local file system, and to pass information from your computer to
 the Web site.
 - CLSID extension vulnerability. Attachments which end with a
 CLSID file extension do not show the actual full extension of
 the file when saved and viewed with Windows Explorer. This
 allows dangerous file types to look as though they are simple,
 harmless files - such as JPG or WAV files - that do not need to
 be blocked.
 System requirements:
 Versions of Windows no earlier than Windows 95.
 This update applies to:
 Versions of Internet Explorer no earlier than 4.01
 Versions of MS Outlook no earlier than 8.00
 Versions of MS Outlook Express no earlier than 4.01
 How to install
 Run attached file q216309.exe
 How to use
 You don't need to do anything after installing this item.
 For more information about these issues, read Microsoft Security
 Bulletin MS02-005, or visit link below.
 http://www.microsoft.com/windows/ie/downloads/critical/default.asp
 If you have some questions about this article contact us at
 rdquest12@microsoft.com
 Thank you for using Microsoft products.
 With friendly greetings,
 MS Internet Security Center.
 ----------------------------------------
 ----------------------------------------
 Microsoft is registered trademark of Microsoft Corporation.
 Windows and Outlook are trademarks of Microsoft Corporation.

It should be noted that due to bugs in worm's code this message might not be fully visible when it arrives on a recepient's system.

The body of the message describes a Microsoft vulnerability and tries to make the recipient click on the attached file.

This worm's file is 122880 bytes long and it is a dropper for several worm components. Being run, the worm's dropper outputs a dialog box asking a user if he wants to install a security update.

If a user clicks 'Yes', the worm shows the unpacking dialog with progress bar and in the end opens a messagebox informing that the update has been installed.

If a user clicks 'No' the worm installs itself too, but doesn't show any dialog or messageboxes.

The worm sets an infection marker so if it is run on an already infected system, then it shows the following message:

The following entry in the Registry is used as infection marker:

[HKEY_LOCAL_MACHINE\Software\AVTech\Settings]
 "Installed" = "... by Begbie"

When run, the worm drops several files to a system:

\%WinDir%\Q216309.exe		- a copy of a dropper
 \%WinDir%\BcTool.exe		- the mass-mailing component
 \%WinDir%\WinNetw.exe		- e-mail address searching component
 \%WinDir%\GfxAcc.exe		- backdoor component
 \%WinSysDir%\Vtnmsccd.dll	- a copy of a dropper
 \%WinSysDir%\MSWinsck.ocx	- standard Winsock library

where \%WinDir%\ is Windows root directory and \%WinSysDir%\ is Windows System directory.

The e-mail address searching component also creates a file with the name 02_N803.dat in Windows directory and stores all found e-mail addresses there. This file is then loaded by the main mass-mailing component and the worm sends itself to all found e-mail addresses.

The worm adds startup strings for its mass-mailing and backdoor components to the Registry. The following keys are created:

[HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run]
 "3DfxAcc" = "\%WinDir%\GfxAcc.exe"
 "LoadDBackUp" = "\%WinDir%\BcTool.exe"

where \%WinDir%\ is Windows root directory. This way both components are started during every Windows session.

To get rid of the worm it's enough to delete all its components from an infected system. If some components are locked while Windows is active, they have to be deleted from pure DOS (in case of Windows 9x system) or renamed with a different extension (EXA for example) with immediate system restart (in case of NT-based system). After restart the renamed components can be deleted.

Detection of Gibe worm was added into F-Secure Anti-Virus updates published on 6th of March 2002.





Technical Details: Katrin Tocheva and Alexey Podrezov; F-Secure Corp.; March 6th, 2002


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