Class Email-Worm
Platform VBS

Technical Details

This Internet worm infects computer with installed Windows 9x and Internet
Explorer 5.0 without Scriptlet.TypeLib hotfix (MS99-032). The worm spreads via
E-mail by sending infected messages from affected computers. While spreading
the worm uses MS Outlook and sends itself to all addresses that are stored in
MS Outlook Address Book. The worm also has alternate spreading method that
does not use Outlook at all.

The worm arrives to a computer as email message in HTML format. The subject of
message may be vary. Message body has no visible text but contain script that
is worm itself.

At the moment message is opening or displayed in preview pane, script
activates and worm’s code executing. At this moment ActiveX warning may appear
on display:

An ActiveX control on this page might be unsafe to interact with other parts
of the page. Do you want to allow this interaction?
[YES] [NO]

Choosing [NO] will not allow the worm to execute.

Being activated worm drops some files that are worm’s parts, gets access to
Outlook and spreads using it, then searching on computer hard drive for email
addresses, collects them and use in alternate spreading routine.

Composing infected message to send, the worm choosing subject from one of
existing messages from Outlook Inbox. The worm also attaches HTML file with
worm code. File name is name of one of attachments existing in inbox with
added “(9 Kbytes).vbs”. Thus, infected message contain worm code twice – in
the message HTML body and in the attachment.

The worm adds itself to all signature files used by MS Outlook. This means
every composed message in HTML format will contain worm code.

The worm replaces Internet Explorer start page with blank one. Four days after
infection the worm replaces start page again with URL pointed to

The worm has alternate spreading method that does not use Outlook at all. This
routine searches on local hard drive for files with extensions “txt”, “na2”,
“wab”, “mbx”, “dbx” and “dat” (these are usual extensions for mail databases)
and then searches and collects e-mail addresses in these files. Collected
addresses then posted (using HTML form) to worm’s author internet site.
Special script on that site send infected messages directly from site to every
address received. Such messages have same address in “From” and “To” fields
and contain only HTML body with worm code inside. This alternate spreading
method will not work as soon as worm author’s site will be closed.

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