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AUSCERT External Security Bulletin Redistribution
ESB-2015.2663
Cisco ASA Software DHCPv6 Relay Denial of Service Vulnerability
22 October 2015
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AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco ASA Software
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Denial of Service -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2015-6324
Original Bulletin:
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20151021-asa-dhcp1
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Cisco Security Advisory
Cisco ASA Software DHCPv6 Relay Denial of Service Vulnerability
High
Advisory ID:
cisco-sa-20151021-asa-dhcp1
Published:
2015 October 21 16:00 GMT
Version 1.0:
Final
CVSS Score:
Base - 7.1
Workarounds:
No workarounds available
Cisco Bug IDs:
CSCus56252
CSCus57142
CVE-2015-6324
CWE-399
Email
Summary
A vulnerability in the DHCPv6 relay feature of Cisco Adaptive Security
Appliance (ASA) software could allow an unauthenticated, remote attacker
to cause an affected device to reload.
The vulnerability is due to insufficient validation of DHCPv6
packets. Cisco ASA Software is affected by this vulnerability only if
the software is configured with the DHCPv6 relay feature. An attacker
could exploit this vulnerability by sending crafted DHCPv6 packets to
an affected device.
Note: Only DHCPv6 packets directed to the Cisco ASA interface where the
DHCPv6 relay is enabled can be used to trigger this vulnerability. This
vulnerability affects systems configured in routed or transparent
firewall mode and in single or multiple context mode. This vulnerability
can be triggered only by IPv6 traffic.
This vulnerability is documented in Cisco bug IDs CSCus56252 (registered
customers only) and CSCus57142 (registered customers only) and have
been assigned CVE ID CVE-2015-6324.
Cisco has released software updates that address this
vulnerability. Workarounds that mitigate this vulnerability are not
available. This advisory is available at the following link:
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20151021-asa-dhcp1
Affected Products
Cisco ASA Software running on the following products is affected by
this vulnerability:
Cisco ASA 5500 Series Adaptive Security Appliances
Cisco ASA 5500-X Series Next-Generation Firewalls
Cisco ASA Services Module for Cisco Catalyst 6500 Series Switches
and Cisco 7600 Series Routers
Cisco ASA 1000V Cloud Firewall
Cisco Adaptive Security Virtual Appliance (ASAv)
Consult the "Fixed Software" section of this security advisory for
more information about the affected releases...
Vulnerable Products
Cisco ASA Software is affected by this vulnerability only if the DHCPv6
relay feature is configured.
To determine whether the DHCPv6 relay feature is configured, use the show
running-config ipv6 dhcprelay command and verify that the feature is
enabled on at least one interface.
The following example shows the DHCPv6 relay feature enabled on the interface
outside:
asa#show running-config ipv6 dhcprelay
ipv6 dhcprelay enable outside
Note: The DHCPv6 relay feature is not configured by default.
Determining the Running Software Version
To determine whether a vulnerable version of Cisco ASA Software is running
on an appliance, administrators can use the show version command. The
following example shows the results for an appliance running Cisco ASA
Software version 9.2(1):
ciscoasa# show version | include Version
Cisco Adaptive Security Appliance Software Version 9.2(1)
Device Manager Version 7.4(1)
Customers who use Cisco Adaptive Security Device Manager (ASDM) to manage
devices can locate the software version in the table that appears in the login
window or the upper-left corner of the Cisco ASDM window.
Products Confirmed Not Vulnerable
Cisco FirePOWER 9300 ASA Security Module is not affected by this vulnerability.
No other Cisco products are currently known to be affected by this
vulnerability.
Indicators of Compromise
A Cisco ASA device reloading with thread name DHCPv6 Relay may indicate
exploitation of this vulnerability.
The thread name is listed at the beginning of the crashinfo file. The
crashinfo file can be accessed by using the show crashinfo command. The
following example shows a crashinfo file with thread name DHCPv6 Relay:
ciscoasa# show crashinfo
: Saved_Crash
Thread Name: DHCPv6 Relay
.
.
.
Customers should contact their support organization if they suspect active
exploitation of this vulnerability to have the traceback decoded to confirm
that the crash is due to this vulnerability.
Note: Because the reload can be triggered by a crafted DHCPv6 packet, not
all cases may be due to malicious activity.
Workarounds
There are no workarounds that mitigate this vulnerability. However,
administrators may disable the affected feature.
Fixed Software
When considering software upgrades, customers are advised to
consult the Cisco Security Advisories and Responses archive at
http://www.cisco.com/go/psirt and review subsequent advisories to
determine exposure and a complete upgrade solution.
In all cases, customers should ensure that the devices to upgrade
contain sufficient memory and confirm that current hardware and
software configurations will continue to be supported properly by the
new release. If the information is not clear, customers are advised to
contact the Cisco Technical Assistance Center (TAC) or their contracted
maintenance providers.
In the following table, the left column lists major releases of Cisco
ASA Software. The center column indicates whether a major release
is affected by the vulnerability described in this advisory and the
first minor release that includes the fix for this vulnerability. The
right column indicates whether a major release is affected by all
the vulnerabilities described in the following advisories and which
release includes fixes for those vulnerabilities:
cisco-sa-20151021-asa-dhcp1
cisco-sa-20150115-asa-dhcp
cisco-sa-20151021-asa-dns1
cisco-sa-20151021-asa-dns2
cisco-sa-20151021-asa-ike
Customers should upgrade to an appropriate release as indicated in
the following table:
Cisco ASA Major Fixed Release for This Advisory First Fixed Release for All Advisories
Release First in the October 2015 ASA Security
Advisory Bundled Publication
7.2 Not affected Affected; migrate to 8.2(5.58) or later
8.2 Not affected 8.2(5.58) and later
8.3 Not affected Affected; migrate to 8.4(7.29) or later
8.4 Not affected 8.4(7.29)
8.5 Not affected Affected; migrate to 9.0(4.37) or later
8.6 Not affected Affected; migrate to 9.0(4.37) or later
8.7 Not affected 8.7(1.17) and later
9.0 9.0(4.37) 9.0(4.37) and later
9.1 9.1(6.6) 9.1(6.8) and later
9.2 9.2(4) 9.2(4) and later
9.3 9.3(3.5) 9.3(3.5) and later
9.4 9.4(2) 9.4(2) and later
9.5 Not affected Not affected
Software Download
Cisco ASA Software can be downloaded from the Software Center on
Cisco.com by visiting http://www.cisco.com/cisco/software/navigator.html.
For Cisco ASA 5500 Series Adaptive Security Appliances and Cisco ASA
5500-X Next Generation Firewall, navigate to the following path. To
find interim versions, click All Releases > Interim on the left side
of the download page.
Products > Security > Firewalls > Adaptive Security Appliances
(ASA) > ASA 5500 Series Adaptive Security Appliances > <your Cisco
ASA model> > Adaptive Security Appliance (ASA) Software
For the Cisco ASA Services Module for Cisco Catalyst 6500 Series
Switches and Cisco 7600 Series Routers, navigate to the following
path. To find interim versions, click All Releases > Interim on the
left side of the download page.
Products > Cisco Interfaces and Modules > Services Modules >
Catalyst 6500 Series / 7600 Series ASA Services Module > Adaptive
Security Appliance (ASA) Software
For the Cisco ASA 1000V Cloud Firewall, navigate to the following path:
Products > Security > Firewalls > Adaptive Security Appliances
(ASA) > ASA 1000V Cloud Firewall
For the Cisco Adaptive Security Virtual Appliance (ASAv), navigate to
the following path:
Products > Security > Firewalls > Adaptive Security Appliances
(ASA) > Adaptive Security Virtual Appliance (ASAv) > Adaptive
Security Appliance (ASA) Software
For the Cisco FirePOWER 9300 ASA Module, navigate to the following path:
Products > Security > Firewalls > Adaptive Security Appliances
(ASA) > Firepower 9000 Series > Firepower 9300 Security Appliance
>Adaptive Security Appliance (ASA) Software
Exploitation and Public Announcements
The Cisco Product Security Incident Response Team (PSIRT) is not aware
of any public announcements or malicious use of the vulnerability that
is described in this advisory.
Source
This vulnerability was found during internal security tests.
URL
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20151021-asa-dhcp1
Revision History
Version Description Section Status Date
1.0 Initial public release. - Final 2015-October-21
Legal Disclaimer
THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND
OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY
OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE
DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO
RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
A stand-alone copy or paraphrase of the text of this document that
omits the distribution URL is an uncontrolled copy, and may lack
important information or contain factual errors. The information in
this document is intended for end-users of Cisco products.
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