Samba fails to properly handle multiple share connection requests

Overview

There is a vulnerability in the smbd process which may allow an attacker to create a denial of service condition.

Description

Samba
Samba is an open-source implementation of SMB/CIFS file and print services. It is frequently included in UNIX and Linux distributions and is typically used provide file and print services to Windows clients.

smbd
The smbd daemon is used to track connections to SMB network shares and printers.

The Problem
By sending a large number of share requests, an attacker can exhaust the system resources available to the smbd process.

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Impact

An attacker may be able to cause a denial of service condition by exhausting the system resources used by the smbd daemon.

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Solution

Upgrade
See the vendor of your operating system for patched smbd packages. Users who compile Samba from source should refer to the Samba webpage to obtain a patched version of the software.

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Workarounds

Restrict Access
Blocking the SMB protocol at the network perimeter will reduce exposure to this vulnerability. Servers using the SMB protocol typically use ports 139/tcp and 445/tcp.

Disable Unnecessary Daemons
Do not enable the smbd daemon on systems that do not need to use the SMB protocol. Some operating systems have the smbd daemon started by default.

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Vendor Information

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Samba Affected

Notified: July 11, 2006 Updated: July 17, 2006

Status

Affected

Vendor Statement

We have not received a statement from the vendor.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

• <http://us1.samba.org/samba/security/CAN-2006-3403.html&gt;
• <http://secunia.com/advisories/20980/&gt;
• <http://secunia.com/advisories/21018/&gt;
• <http://secunia.com/advisories/20983/&gt;
• <http://secunia.com/advisories/21019/&gt;
• <http://frontal2.mandriva.com/security/advisories?name=MDKSA-2006:120&gt;
• <http://www.ubuntu.com/usn/usn-314-1&gt;
• <http://www.securityfocus.com/bid/18927&gt;
• <http://www.mandriva.com/security/advisories?name=MDKSA-2006:120&gt;
• <https://issues.rpath.com/browse/RPL-496&gt;
• <http://www.ubuntuforums.org/showthread.php?t=214283&gt;
• <http://security.gentoo.org/glsa/glsa-200607-10.xml&gt;

Acknowledgements

Thanks to the Samba team for reporting this vulnerability.

This document was written by Ryan Giobbi.

Other Information

CVE IDs:	CVE-2006-3403
Severity Metric:	0.24 Date Public: