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AUSCERT External Security Bulletin Redistribution
ESB-2001.272 -- HPSBMP0107-012
Security Vulnerability in CIFS/9000 Server #2
4 July 2001
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AusCERT Security Bulletin Summary
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Product: CIFS/3000 Server (Samba/iX)
Vendor: Hewlett-Packard
Operating System: HP-UX
Platform: HP3000 MPE/iX
Impact: Modify Arbitrary Files
Access Required: Remote
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Document ID: HPSBMP0107-012
Date Loaded: 20010702
Title: Security Vulnerability in CIFS/9000 Server #2
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HEWLETT-PACKARD COMPANY SECURITY ADVISORY: #0012, 3 July '01
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The information in the following Security Advisory 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 Advisory as soon as possible.
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PROBLEM: CIFS/3000 Server (Samba) - use of certain configuration
options may compromise system security
PLATFORM: All HP3000 MPE/iX servers running Samba/iX
DAMAGE: Data may be appended to arbitrary files and devices
SOLUTION: Remove offending configuration options to avoid vulnerability
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A. Background
The NetBIOS name of remote clients is substituted into the "%m" macro
wherever it occurs in the configuration file smb.conf. The use of
contrived NetBIOS names may result in Samba using a file path
outside of the intended Samba directories. This can be used to
cause Samba to append data to important system files, which in
turn can be used to compromise security on the server.
B. Fixing the problem
An immediate fix is to edit your smb.conf configuration file and
remove all occurances of the macro "%m". Depending on the
requirements of each site, other smb.conf macros may be suitable
replacements.
C. Workarounds
The "log file" option is the most vulnerable to this redefinition
problem. The sample configuration file supplied with CIFS/3000
Server contains the path "/var/opt/samba/log.%m" for this option.
Using this default path does NOT create a vulnerability unless
there happens to exist a subdirectory in /var/opt/samba which
starts with the prefix "log.".
Sites that chooose to maintain the use of the "%m" macro in the
"log file" option should use the default value:
/var/opt/samba/log.%m
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
Under the Maintenance and Support Menu:
click on the "more..." link. Then -
Use the 'Login' tab at the left side of the screen to login
using your ID and password. Check with your system
administrator to see if you have an existing login or use
the "Register" button at the left to create a login. You
will need to login in order to gain access to many areas of
the ITRC. Remember to save the User ID assigned to you, and
your password.
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
HP-UX 11.XX systems.
For information on the HP-UX Security Patch Check tool, see:
http://www.software.hp.com/cgi-bin/swdepot_parser.cgi/cgi/
displayProductInfo.pl?productNumber3DB6834AA"
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 Advisory
to Hewlett-Packard (HP) customers (or the Internet community) for
the purpose of alerting them to problems, if and only if, the
Advisory 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.
______________________________________________________________________
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