Possible Intrusion Attempt?

[Matt LaFelero <ramstryke () yahoo com>]

I'm hoping someone here might be able to shed some light on this 
situation..  

Some of my users have been getting some interesting spam mail.  This is 
the first time I've ever seen a spam mail do this.  When the user opens 
the spam mail, all of a sudden, an Internet Explorer authentication 
boxes pops up.  You know those that ask for username, password, and 
domain.  

Well, I run MS Proxy 2.0 here and the logon with a 2KPro machine is 
integrated so the user never sees this box or has to enter his/her 
password to get on the Web.  

It's strange that this email triggers the authentication box.  What's 
even weirder is that it populates the username for them, with weird 
names.  The names always seem to change from spam mail to spam mail.  I've 
seen iterations like fluff, skank, morton, taxiway.. you name it.

It seems most of the emails are HTML, which can explain a lot.  None of 
them had attachments.  From what I could gather it seems to attempting to 
load a site.  We run Outlook 2000 with SP3 and all hotfixes.

My question is, how is this happening and is it a threat?

----------------------------------------------------------------------------
*** Wireless LAN Policies for Security & Management - NEW White Paper ***
Just like wired networks, wireless LANs require network security policies 
that are enforced to protect WLANs from known vulnerabilities and threats. 
Learn to design, implement and enforce WLAN security policies to lockdown enterprise WLANs.

To get your FREE white paper visit us at:    
http://www.securityfocus.com/AirDefense-incidents
----------------------------------------------------------------------------