I'm wondering if you could reccomend a good anti-virus filter/scanner
thing that I can use to scan the mail going through my lists, ideally
one that would alert me and/or the list admin before sending out mail
that was potentially infected.
Stripping all attachments is certainly a good start. Then it
has recently been pointed out on Bugtraq that it is possible
to infect users of web-mail systems such as hotmail or yahoo
by means of malicious URLs (see below). Because I haven't
gotten around to learning how to do it in Python, I filter in
a little Perl script on the regular expression
(I'd certainly appreciate a patch for Mailman that makes it hold
messages which contain such suspicious URLs).
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From: mparcens at hushmail.com
Date: Wed, 30 May 2001 19:18:08 -0500 (EDT)
To: bugtraq at securityfocus.com
Content-type: multipart/mixed; boundary="Hushpart_boundary_dAfMJfpqUApfpvnobyxrXSpSoIJaULVu"
Subject: Yahoo/Hotmail scripting vulnerability, worm propagation
Title: Yahoo/Hotmail scripting vulnerability, worm propagation
Cross-site-scripting holes in Yahoo and Hotmail make it possible to replicate
a Melissa-type worm through those webmail services.
An email is sent to the victim, who uses Yahoo Mail or Hotmail. Inside the
email is a link to yahoo or hotmail's own server. The link contains escaped
opens a window that could nagivate through the victim's inbox, sending messages
with the malicious link to every email address it finds in the inbox. Because
the window with the victim's inbox.
Who is vulnerable
Users of the Yahoo Mail and Hotmail service. Although the exploit requires
a user to click on a link, two things work for this exploit. (1) The email
comes from a familiar user (sent by the worm), and (2) The link is to a
familiar, trusted server. Theoretically, more services are vulnerable, due
to the proliferation of these holes, but the worm is limited to web mail
Sample links and the worm code can be found at: http://www.sidesport.com/webworm/
Escaping all query data that is echoed to the screen eliminates this problem.
This must be done on every page on a server that can send or read mail for
Both Yahoo and Hotmail were notified on May 23 2001.
mparcens at hushmail.com
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