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AUSCERT External Security Bulletin Redistribution
ESB-1999.100 -- Samba 2.0.5 security fixes
27 July 1999
The Samba Team has released the following advisory concerning security
vulnerabilities in Samba versions prior to 2.0.5 available for various
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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 (email@example.com) who performed a security audit on Samba for
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
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.
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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
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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
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
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Thanks to Olaf Kirch and Caldera for their thorough security audit and
help in producing a suitable fix.
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This security bulletin is provided as a service to AusCERT's members. As
AusCERT did not write the document quoted above, AusCERT has had no control
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NOTE: This is only the original release of the security bulletin. It will
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Previous advisories and external security bulletins can be retrieved from:
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