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Category:   Application (Generic)  >   Telnet Vendors:   [Multiple Authors/Vendors]
(HP Issues Fix) Telnet Daemons May Give Remote Users Root Level Access Privileges
SecurityTracker Alert ID:  1002576
SecurityTracker URL:  http://securitytracker.com/id/1002576
CVE Reference:   GENERIC-MAP-NOMATCH   (Links to External Site)
Date:  Oct 18 2001
Impact:   Execution of arbitrary code via network, Root access via network, User access via network
Fix Available:  Yes  Vendor Confirmed:  Yes  

Description:   TESO reported that many BSD-derived Telnet daemons (servers) contain a vulnerability that may allow a remote user to obtain root level access on the server.

The vulnerability is reportedly due to a buffer overflow in the telnet option handling.

The following systems are reported to be vulnerable:

BSDI 4.x default, FreeBSD [2345].x default, IRIX 6.5, Linux netkit-telnetd < 0.14, NetBSD 1.x default, OpenBSD 2.x, Solaris 2.x sparc, and "almost any other vendor's telnetd".

A remote user can send a specially formatted option string to the remote telnet server and overwrite sensitive memory, causing arbitrary code to be executed with the privileges of the telnet server (which is typically root level privileges).

Telnet options are reportedly processed by the 'telrcv' function. The results of the parsing, which are to be send back to the client, are stored in the 'netobuf' buffer. It is apparently assumed that the reply data is smaller than the buffer size, so no bounds checking is performed. By using a combination of options, especially the 'AYT' Are You There option, it is possible for a remote user to append data to the buffer. It is reported that the characters that can be written to the buffer are limited, which makes constructing a successful exploit difficult.

The report states that a working exploit has been developed for BSDI, NetBSD and FreeBSD. However, the exploit was not released.

Impact:   A remote user can execute arbitrary code on the server with the privileges of the telnet server, which is typically root level privileges.
Solution:   The vendor has released the following patches, available now at:

<http://itrc.hp.com>

10.01 PHNE_24820,
10.10 PHNE_24820,
10.20 PHNE_24821,
SIS 10.20 PHNE_24822 (Telnet kerberos Patch),
10.24 PHNE_25217.

HP notes that the Secure Internet Services (SIS) product, if enabled, has to be disabled before the installation or removal of PHNE_24822 (Telnet kerberos Patch).

Cause:   Boundary error
Underlying OS:  UNIX (HP/UX)
Underlying OS Comments:  many Linux and Unix OSs are vulnerable, but not all - see the Alert text for more information

Message History:   This archive entry is a follow-up to the message listed below.
Jul 18 2001 Telnet Daemons May Give Remote Users Root Level Access Privileges



 Source Message Contents

Subject:  security bulletins digest



Document ID:  HPSBUX0110-172
Date Loaded:  20011016
      Title:  Sec. Vulnerability in telnetd

-----------------------------------------------------------------
   HEWLETT-PACKARD COMPANY SECURITY BULLETIN: #0172
   Originally issued: 16 October 2001
 -----------------------------------------------------------------

The information in the following Security Bulletin should be acted
upon as soon as possible.  Hewlett-Packard Company will not be
liable for any consequences to any customer resulting from customer's
failure to fully implement instructions in this Security Bulletin as
soon as possible.

 ------------------------------------------------------------------
PROBLEM: Systems running telnetd may permit unauthorized remote
         access.
         See: http://www.cert.org/advisories/CA-2001-21.html

         This vulnerability has been assigned the identifier
         CAN-2001-0554 by the Common Vulnerabilities and Exposures
         (CVE) group:
     http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2001-0554


PLATFORM: HP9000 Servers running HP-UX releases 10.X only.

DAMAGE:  An intruder can potentially execute arbitrary code
         with the privileges of the telnetd process.

SOLUTION: Apply the following patches to the release specified.

        10.01       PHNE_24820,
        10.10       PHNE_24820,
        10.20       PHNE_24821,
    SIS 10.20       PHNE_24822 (Telnet kerberos Patch),
        10.24       PHNE_25217.

MANUAL ACTIONS: The Secure Internet Services (SIS) product, if
                enabled, has to be disabled before the installation
                or removal of PHNE_24822 (Telnet kerberos Patch).

AVAILABILITY:   The patches are available now from http://itrc.hp.com.

 ------------------------------------------------------------------
 A. Background
     A potential remotely exploitable buffer overflow in telnetd has
     been reported to Hewlett-Packard Company.  It is unique to HP-UX
     releases 10.X only.

 B. Fixing the problem
     Disable telnetd (by commenting out the /etc/inetd.conf entry for
     telnetd and running '/usr/sbin/inetd -c') if telentd is not needed
     on your system.

     Install the appropriate patch from the list below.

 C. Recommended solution

    Apply the following patches to the release specified.

        10.01       PHNE_24820,
        10.10       PHNE_24820,
        10.20       PHNE_24821,
    SIS 10.20       PHNE_24822,
        10.24       PHNE_25217.

    All patches are available now from http://itrc.hp.com.

 D. To subscribe to automatically receive future NEW HP Security
    Bulletins from the HP IT Resource Center via electronic
    mail, do the following:

    Use your browser to get to the HP IT Resource Center page
    at:

       http://itrc.hp.com

    Use the 'Login' tab at the left side of the screen to login
    using your ID and password.  Use your existing login or the
    "Register" button at the left to create a login, in order to
    gain access to many areas of the ITRC.  Remember to save the
    User ID assigned to you, and your password.

    In the left most frame select "Maintenance and Support".

    Under the "Notifications" section (near the bottom of
    the page), select "Support Information Digests".

    To -subscribe- to future HP Security Bulletins or other
    Technical Digests, click the check box (in the left column)
    for the appropriate digest and then click the "Update
    Subscriptions" button at the bottom of the page.

    or

    To -review- bulletins already released, select the link
    (in the middle column) for the appropriate digest.

    To -gain access- to the Security Patch Matrix, select
    the link for "The Security Bulletins Archive".  (near the
    bottom of the page)  Once in the archive the third link is
    to the current Security Patch Matrix. Updated daily, this
    matrix categorizes security patches by platform/OS release,
    and by bulletin topic.  Security Patch Check completely
    automates the process of reviewing the patch matrix for
    11.XX systems.

    For information on the Security Patch Check tool, see:
    http://www.software.hp.com/cgi-bin/swdepot_parser.cgi/cgi/
    displayProductInfo.pl?productNumber=B6834AA"

    The security patch matrix is also available via anonymous
    ftp:

    ftp.itrc.hp.com:~ftp/export/patches/hp-ux_patch_matrix

    On the "Support Information Digest Main" page:
    click on the "HP Security Bulletin Archive".


 E. To report new security vulnerabilities, send email to

    security-alert@hp.com

    Please encrypt any exploit information using the
    security-alert PGP key, available from your local key
    server, or by sending a message with a -subject- (not body)
    of 'get key' (no quotes) to security-alert@hp.com.

    Permission is granted for copying and circulating this
    Bulletin to Hewlett-Packard (HP) customers (or the Internet
    community) for the purpose of alerting them to problems,
    if and only if, the Bulletin is not edited or changed in
    any way, is attributed to HP, and provided such reproduction
    and/or distribution is performed for non-commercial purposes.

    Any other use of this information is prohibited. HP is not
    liable for any misuse of this information by any third party.
 ________________________________________________________________
-----End of Document ID:  HPSBUX0110-172--------------------------------------

 
 


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