RE: Cisco PIX Firewall MailGuard Vulnerability

From: Jerome Tytgat (j.tytgatat_private)
Date: Tue Sep 25 2001 - 05:42:01 PDT

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    rather outdated... 10-5-2000...
    
    All recents - "less than one year" - binary
    are ok (>4.4.7, 5.1.4, 5.2.3, 5.3.1, 6.0.1).
    
    in fact the order of commands was not checked
    (you could send a DATA before a RCPT TO).
    
    And after sending a DATA command, command was not
    checked anymore.
    
    Simply send a DATA just after a HELO is refused by
    the mail server with a 500 error but the pix saws 
    the DATA command and is not checking anymore commands.
    
    So the mailserver was vulnerable against attack if it has
    bug (such as overflow).
    
    The SMTP fixup is here to prevent use of some functions
    like EXPN, VRFY.
    
    _______________________________________________________________
    ENERGIS
    Jerome Tytgat
    Network and Security Administrator
    mailto:j.tytgatat_private        http://www.energis.fr
    tel : (33) 03 88 78 77 77       2, rue paul Rohmer
    fax : (33) 03 88 78 80 00       F-67087 Strasbourg Cedex 2
    _______________________________________________________________
    
     
    
    
    
    
    
    
    > -----Message d'origine-----
    > De : Fabio Pietrosanti (naif) [mailto:naifat_private]
    > Envoye : mardi 25 septembre 2001 12:06
    > A : vuln-devat_private
    > Objet : Cisco PIX Firewall MailGuard Vulnerability
    > 
    > 
    > Hi,
    > 
    > i have received the advisory from cisco about the vulnerability 
    > in the subject
    > described here:
    > http://www.cisco.com/warp/public/707/PIXfirewallSMTPfilter-pub.shtml
    > 
    > I discovered the old mailguard vulnerability, and i would like to know if
    > someone could explain in details about this new kind of attack 
    > against SMTP
    > filter .
    > 
    > Regards
    > 
    > -- 
    > 
    > Fabio Pietrosanti ( naif )
    > E-mail: naifat_private - naifat_private
    > PGP Key (DSS) http://naif.itapac.net/naif.asc
    > --
    > Free advertising: www.openbsd.org Multiplatform Ultra-secure OS
    > Free Flame: IPFilter sucks ! 
    > 
    



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