[VulnWatch] iDEFENSE Security Advisory 10.13.05: Multiple Vendor XMail 'sendmail' Recipient Buffer Overflow Vulnerability

From: iDEFENSE Labs (labs-no-reply_at_idefense.com)
Date: 10/13/05

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    Date: Thu, 13 Oct 2005 13:16:12 -0400
    To: <bugtraq@securityfocus.com>, <vulnwatch@vulnwatch.org>, <full-disclosure@lists.grok.org.uk>
    
    

    Multiple Vendor XMail 'sendmail' Recipient Buffer Overflow Vulnerability

    iDEFENSE Security Advisory 10.13.05
    www.idefense.com/application/poi/display?id=321&type=vulnerabilities
    October 13, 2005

    I. BACKGROUND

    XMail is an Internet and intranet mail server. XMail sources compile
    under GNU/Linux, FreeBSD, OpenBSD, NetBSD, OSX, Solaris and NT/2K/XP.

    More information can be found at the vendor website:

       http://www.xmailserver.org/

    II. DESCRIPTION

    Local exploitation of a buffer overflow vulnerability in XMail, as
    distributed with multiple vendors' operating systems, allows local
    attackers to execute arbitrary code with elevated privileges.

    The vulnerability exists because of insufficent bounds checking on
    user-supplied data. Specifically, the AddressFromAtPtr function fails to
    check bounds on arguments passed from other functions, and as a result
    an exploitable stack overflow condition occurs when specifying the "-t"
    command line option. The "-t" command line option allows users to
    specify the recipient value in the text of the message on a line
    beginning with "To:". XMail passes the user-supplied value without
    bounds checking to AdressFromAtPtr and attempts to store the hostname
    portion of the e-mail address in a 256-byte buffer. Crafted e-mail
    addresses can overflow the buffer and overwrite stack process control
    data, resulting in local code execution with elevated privileges.

    III. ANALYSIS

    Successful exploitation will result in code execution with elevated
    privileges. XMail is distributed in RPM, DEB and source format. The RPM
    distribution installs the sendmail binary with setuid root privileges.
    Exploitation of XMail installed from RPM will yield root. Other
    distribution formats install the sendmail binary as setgid mail.
    Exploitation resulting in group mail privileges will allow an attacker
    to read all unencrypted mail stored locally in the system mail folders.

    IV. DETECTION

    iDEFENSE Labs has confirmed the existence of this vulnerability in XMail
    1.21.

    V. WORKAROUND

    As a workaround solution, local mail delivery can be restricted and a
    standard mail user-agent may be used to talk to the XMail SMTP server.

    VI. VENDOR RESPONSE

    The vendor has released XMail 1.22 to address this issue which is
    available for download at:

       http://www.xmailserver.org/

    VII. CVE INFORMATION

    The Common Vulnerabilities and Exposures (CVE) project has assigned the
    name CAN-2005-2943 to this issue. This is a candidate for inclusion in
    the CVE list (http://cve.mitre.org), which standardizes names for
    security problems.

    VIII. DISCLOSURE TIMELINE

    10/12/2005 Initial vendor notification
    10/12/2005 Initial vendor response
    10/13/2005 Coordinated public disclosure

    IX. CREDIT

    The discoverer of this vulnerability wishes to remain anonymous.

    Get paid for vulnerability research
    http://www.idefense.com/poi/teams/vcp.jsp

    Free tools, research and upcoming events
    http://labs.idefense.com

    X. LEGAL NOTICES

    Copyright (c) 2005 iDEFENSE, Inc.

    Permission is granted for the redistribution of this alert
    electronically. It may not be edited in any way without the express
    written consent of iDEFENSE. If you wish to reprint the whole or any
    part of this alert in any other medium other than electronically, please
    email customerservice@idefense.com for permission.

    Disclaimer: The information in the advisory is believed to be accurate
    at the time of publishing based on currently available information. Use
    of the information constitutes acceptance for use in an AS IS condition.
    There are no warranties with regard to this information. Neither the
    author nor the publisher accepts any liability for any direct, indirect,
    or consequential loss or damage arising from use of, or reliance on,
    this information.


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