JS/Kak@M

This page shows details and results of our analysis on the malware JS/Kak@M

Overview

This is a virus detection. Viruses are programs that self-replicate recursively, meaning that infected systems spread the virus to other systems, which then propagate the virus further. While many viruses contain a destructive payload, it's quite common for viruses to do nothing more than spread from one system to another.


Minimum Engine

5600.1067

File Length

0

Description Added

1999-12-31

Description Modified

2003-02-20

Malware Proliferation

Characteristics

In-depth details of JS/Kak@M

This worm was first discovered by AVERT in October 1999 and added detection for it within 4051 DAT updates. Virus Patrol, a newsgroup scanning program from NAI, continues to identify occurrences of this Internet worm in newsgroup postings which is an indication that worm is continuing to spread. AVERT recommends adding ".HT?" to file extensions scanned for protection, and also ensure users have installed the security patch from Microsoft mentioned below.

Another dangerous aspect of this Internet worm is the ability to continuously re-infect unpatched systems if the preview pane is enabled and you browse messages, including ones in your own "Sent Items" folder, which contain this Internet worm. This is another strong reason to update to the security patch, if not already.*

This is an Internet worm which uses JavaScript and an ActiveX control, called "Scriptlet Typelib", to propagate itself through email using MS Outlook Express. This worm consists of 3 components, an HTA file (HTML Application), a REG file (Registration Entries Update) and a BAT file (MS-DOS Batch).

When an e-mail or newsgroup message infected by this worm is opened by a reader which supports Javascript in HTML, the script checks to see if MS Internet Explorer 5 or higher is installed. If it is, using an ActiveX exploit known as "Scriptlet TypeLib", the script writes the KAK.HTA file to the Startup folder of the local machine. This will launch the code embedded in the HTA file at the next Windows startup. Microsoft has published a security update which addresses this ActiveX exploit and users are encouraged to update their systems with this component. With this update installed, users are questioned if they wish to run the ActiveX control which "might be unsafe".

For more details on this vulnerability and to obtain a patch from Microsoft, see this link:
Microsoft Security Bulletin

To obtain a patch from Microsoft, see this link:
http://www.microsoft.com/msdownload/iebuild/scriptlet/en/scriptlet.htm

For current security bulletins from Microsoft, see this link:
Current Bulletins.

Email messages written in HTML format will be coded with the Internet worm on infected systems due to the default signature modification on infected systems. The email application Outlook is a target of this Internet worm for propagation due to its support for HTML format messages. If an email message is coded with the worm code and it is allowed to run, files are written to the local machine in different locations-

c:\windows\kak.htm
c:\windows\system\(name).hta

kak.hta is written to either folder:
French Windows
C:\WINDOWS\Menu Dmarrer\Programmes\Dmarrage\kak.hta

English Windows
c:\windows\Start Menu\Programs\StartUp\

In the above list, "(name)" is a seemingly random 8 character name (e.g. 98278AE0.HTA) however it is related directly to a registry entry.

This worm first copies the original AUTOEXEC.BAT file to AE.KAK. Then the AUTOEXEC.BAT file is modified to overwrite the file KAK.HTA and then delete it from the StartUp folder. The system registry is also modified when the script executes a shell registry update using regedit and the REG file written to the local system. The registry modification is this-

HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
cAg0u = "C:\WINDOWS\SYSTEM\(name).hta"

The entry "(name)" is an 8 character name (e.g. 98278AE0.HTA).

The email spreading method is possible by a registry modification which adds a signature to MS Outlook. The signature is set to include the file "C:\WINDOWS\kak.htm" and is set as the default signature such that the worm is spread on all outgoing email if the signature is included.

Finally this worm also has a payload which is date activated.

On the 1st of the month, and beginning from 6PM local time, a message is displayed:

"Kagou-Anti-Kro$oft says not today!"

Symptoms

Recipients of messages containing JS/Kak@M may receive warning messages such as:
"Do you want to allow software such as ActiveX controls and plug-ins to run?"

Users should select "NO" to this question. Also another warning dialogue box could be displayed:
"Scripts are usually safe. Do you want to allow scripts to run?"

Users should also select "NO" to this question. Further indications of infection are the existence of files KAK.HTA and KAK.HTM as mentioned above, registry modifications as mentioned above, added or modified default signature as mentioned above.

On the 1st of the month, and beginning from 6PM local time, a message is displayed:

"Kagou-Anti-Kro$oft says not today!"

Another possible message is a fake error message with this description:

"S3 driver memory alloc failed"

After this, Windows is instructed to shutdown.

Method of Infection

Opening email messages which are composed in HTML format and which contain the script will install the Internet worm on supported systems as mentioned above. The HTA file is written to the local machine as is the HTM file and both are created at system startup, and with each composition of HTML format email message.

Removal of this Internet worm consists of several steps:

* close email client(s)
* install the MS patch mentioned above
* remove KAK.HTA and/or KAK.HTM
* turn off "preview pane"(optional)
* delete the default email signature setting (Tools/Options/Signature)
* delete messages which are not needed which may contain the embedded script

Users may also benefit by removing Windows Scripting Host from their Windows environment. To do this in Windows 9x, go to "Control Panel" and choose "Add/Remove Programs". Click on the "Windows Setup" tab and double click on "Accessories". Scroll down to "Windows Script Host" and uncheck it and choose "OK". It may be necessary to reboot the system. For additional help or support, visit Microsoft's Support Site.

Users may also want to disable "Active Scripting" in the "Restricted Sites" zone and set E-Mail to run in the "Restricted Sites" zone. To do this:

-open Internet Explorer
-choose the Tools menu
-choose Internet Options
-click the Security tab
-click the Restricted Sites icon
-click "Custom Level"
-scroll down to "Active Scripting" and set it to Disable or Prompt
-Click OK
-open Outlook
-choose the Tools menu
-choose Options
-click the Security Tab
-In the "Security Zones" section, choose the "Restricted Sites" zone

Removal

Use specified engine and DAT files for detection and removal.

Removal of this Internet worm consists of several steps:

* close email client(s)
* install the MS patch mentioned above
* remove the .HTA and/or .HTML files associated with this threat
* turn off 'preview pane' (optional)
* delete the default email signature setting (Tools/Options/Signature)
* delete messages which are not needed which may contain the embedded script

Users may also benefit by removing Windows Scripting Host from their Windows environment. To do this in Windows 9x, go to 'Control Panel' and choose 'Add/Remove Programs'. Click on the 'Windows Setup' tab and double click on 'Accessories'. Scroll down to 'Windows Script Host' and uncheck it and choose 'OK'. It may be necessary to reboot the system. For additional help or support, visit Microsoft's Support Site .

Users may also want to disable 'Active Scripting' in the 'Restricted Sites' zone and set E-Mail to run in the 'Restricted Sites' zone. To do this:

-open Internet Explorer
-choose the Tools menu
-choose Internet Options
-click the Security tab
-click the Restricted Sites icon
-click 'Custom Level'
-scroll down to 'Active Scripting' and set it to Disable or Prompt
-Click OK
-open Outlook
-choose the Tools menu
-choose Options
-click the Security Tab
-In the 'Security Zones' section, choose the 'Restricted Sites' zone

AVERT Recommended Updates :

* scriptlet.typelib/Eyedog vulnerability patch

* Malformed E-mail MIME Header vulnerability patch

* Exchange 5.5 post SP3 Information Store Patch 5.5.2652.42 - this patch corrects detection issues with GroupShield

Additionally, Network Administrators can configure this update using an available tool - visit this link for more information .

Variants

JS/Kak.worm.b
JS/Kak.worm.c