Vulnerability Note VU#313836

Samba fails to properly handle multiple share connection requests

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.

II. Impact

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.

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.

Systems Affected

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

Credit

Thanks to the Samba team for reporting this vulnerability.

This document was written by Ryan Giobbi.

Other Information

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