W32/Gibe-A

Name: W32/Gibe-A
Aliases: W32/Gibe@MM
Type: Win32 worm
Date: 5 March 2002

At the time of writing Sophos has received just one report of this worm from the wild.

Description:

W32/Gibe-A is a worm which spreads attached to an email which appears to come from Microsoft. The email will have the following characteristics:

Subject line: Internet Security Update
Attached file: q216309.exe
Message text:

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.
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.

If q216309.exe is run it will display the message "This will install Microsoft Security Update. Do you wish to continue ? ".
It then copies itself to q216309.exe in the Windows folder and vtnmsccd.dll in the Windows system folder. It also drops and executes bctool.exe, winnetw.exe and gfxacc.exe in the Windows folder and creates the file 02_n803.dat in which it stores information about email recipients.

Bctool.exe and winnetw.exe attempt to send out the emails as described above. Gfxacc.exe runs as a background process and opens port 12387, which could allow an intruder to gain remote access and control over the machine.

The worm sets the following registry keys:

HKLM\Software\AVTech\Settings\Default Address = <default address>
HKLM\Software\AVTech\Settings\DefaultServer = <default server>
HKLM\Software\AVTech\Settings\Installed = ...by Begbie
HKLM\Software\Microsoft\Windows\
CurrentVersion\Run\3dfx Acc = <path to gfxacc.exe>
HKLM\Software\Microsoft\Windows\
CurrentVersion\Run\LoadDBackup = <path to bctool.exe>


Read the analysis at
http://www.sophos.com/virusinfo/analyses/w32gibea.html