Bugtraq mailing list archives

Samba 2.0.5 security fixes


From: tridge () SAMBA ORG (Andrew Tridgell)
Date: Wed, 21 Jul 1999 12:35:12 +1000


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Samba 2.0.5 has just been released. This fixes a number of bugs,
including 3 security holes. The security holes were discovered by Olaf
Kirch (okir () caldera de) who performed a security audit on Samba for
Caldera.

The security holes were:

1) a denial of service attack on nmbd (the netbios name service
   daemon). The attack made nmbd spin using up CPU resources until it
   was killed.

2) A buffer overflow in the message service in smbd. This was
   exploitable if the system administrator had set the "message
   command" option in smb.conf. This option is not set by default.

3) A race condition in smbmnt which would allow a user to mount at
   arbitrary points in the filesystem. This could only be exploited if
   smbmnt is setuid, which it is not by default.

While no instances of these holes being exploited are known, it would
not be wise to just ignore these issues. A motivated attacker could
almost certainly produce an exploit very quickly.

New release
- -----------

The Samba 2.0.5 release fixes these and other bugs. See
http://www.samba.org/ for the release notes and download.

The Samba 2.0.5 release has the following MD5 checksum
    9fa63ff151ae697648020df37464eca9 b samba-2.0.5.tar.gz

Workarounds
- -----------

If you cannot upgrade to version 2.0.5 then we recommend the following
action as temporary workarounds:

1) remove the "message command" option from smb.conf if you have set
   it.

2) remove the setuid bit from smbmnt if it is set (use "chmod u-s smbmnt")

3) if nmbd starts using large amounts of CPU then kill and restart
   it.

Credits
- -------

Thanks to Olaf Kirch and Caldera for their thorough security audit and
help in producing a suitable fix.

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