Hash: SHA256

             AUSCERT External Security Bulletin Redistribution

               Resource exhaustion in IP fragment reassembly
                              23 August 2018


        AusCERT Security Bulletin Summary

Product:           FreeBSD kernel
Publisher:         FreeBSD
Operating System:  FreeBSD
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2018-6923  

Reference:         ESB-2018.2417

Original Bulletin: 

- --------------------------BEGIN INCLUDED TEXT--------------------

FreeBSD -- Resource exhaustion in IP fragment reassembly

Affected packages
11.2 <= FreeBSD-kernel < 11.2_2
11.1 <= FreeBSD-kernel < 11.1_13


VuXML ID  359e1548-a652-11e8-805b-a4badb2f4699
Discovery 2018-08-14
Entry     2018-08-22

Problem Description:

A researcher has notified us of a DoS attack applicable to another operating
system. While FreeBSD may not be vulnerable to that exact attack, we have
identified several places where inadequate DoS protection could allow an
attacker to consume system resources.

It is not necessary that the attacker be able to establish two-way
communication to carry out these attacks. These attacks impact both IPv4 and
IPv6 fragment reassembly.


In the worst case, an attacker could send a stream of crafted fragments with a
low packet rate which would consume a substantial amount of CPU.

Other attack vectors allow an attacker to send a stream of crafted fragments
which could consume a large amount of CPU or all available mbuf clusters on
the system.

These attacks could temporarily render a system unreachable through network
interfaces or temporarily render a system unresponsive. The effects of the
attack should clear within 60 seconds after the attack stops.


CVE Name         CVE-2018-6923
FreeBSD Advisory SA-18:10.ip

- --------------------------END INCLUDED TEXT--------------------

You have received this e-mail bulletin as a result of your organisation's
registration with AusCERT. The mailing list you are subscribed to is
maintained within your organisation, so if you do not wish to continue
receiving these bulletins you should contact your local IT manager. If
you do not know who that is, please send an email to auscert@auscert.org.au
and we will forward your request to the appropriate person.

NOTE: Third Party Rights
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
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
organisation, and should be considered in accordance with your organisation's
site policies and procedures. AusCERT takes no responsibility for consequences
which may arise from following or acting on information or advice contained in
this security bulletin.

NOTE: This is only the original release of the security bulletin.  It may
not be updated when updates to the original are made.  If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author's website to ensure that the information is still current.

Contact information for the authors of the original document is included
in the Security Bulletin above.  If you have any questions or need further
information, please contact them directly.

Previous advisories and external security bulletins can be retrieved from:


Australian Computer Emergency Response Team
The University of Queensland
Qld 4072

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 7031
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AusCERT personnel answer during Queensland business hours
                which are GMT+10:00 (AEST).
                On call after hours for member emergencies only.
Comment: http://www.auscert.org.au/render.html?it=1967