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AUSCERT External Security Bulletin Redistribution
ESB-2015.2664
Cisco ASA Software VPN ISAKMP 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-2015-6327
Original Bulletin:
http://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20151021-asa-ike
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Cisco Security Advisory
Cisco ASA Software VPN ISAKMP Denial of Service Vulnerability
High
Advisory ID:
cisco-sa-20151021-asa-ike
Published:
2015 October 21 16:00 GMT
Version 1.0:
Final
CVSS Score:
Base - 7.8
Workarounds:
No workarounds available
Cisco Bug IDs:
CSCus94026
CVE-2015-6327
CWE-399
Summary
A vulnerability in the Internet Key Exchange (IKE) version 1 (v1) code
of Cisco Adaptive Security Appliance (ASA) Software could allow an
unauthenticated, remote attacker to cause an affected system to reload.
The vulnerability is due to improper handling of Internet Security
Association and Key Management Protocol (ISAKMP) packets. An attacker
could exploit this vulnerability by sending crafted UDP packets to
the affected system. A successful exploit could allow the attacker to
cause an affected system to reload.
Note: Only traffic directed to the affected system can be used to exploit
this vulnerability. This vulnerability affects systems configured in
routed firewall mode only and in single or multiple context mode. This
vulnerability can be triggered by IPv4 and IPv6 traffic.
This vulnerability is documented in Cisco bug ID CSCus94026 (registered
customers only) and has been assigned Common Vulnerabilities and
Exposures (CVE) ID CVE-2015-6327.
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-ike
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)
See 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 if the system is
configured to terminate IKEv1 VPN connections.
This includes the following:
LAN-to-LAN using IKEv1
Remote Access VPN using the IPSec VPN client
Layer 2 Tunneling Protocol (L2TP)-over-IPSec VPN connections
Cisco ASA Software is not affected by this vulnerability if the system
is configured to terminate the following VPN connections:
Clientless SSL
AnyConnect SSL
IKEv2 AnyConnect
IKEv2 LAN-to-LAN
To determine whether the Cisco ASA is configured to terminate IKEv1
VPN connections, a crypto map should be configured for at least one
interface. Administrators should use the show running-config crypto
map | include interface command and verify that it returns output. The
following example shows a crypto map called cmap configured on the
outside interface:
ciscoasa# show running-config crypto map | include interface
crypto map outside_map interface outside
Additionally IKEv1 should also be enabled on that interface. This can
be determined by using the show running-config crypto ikev1 command,
or show running-config | include crypto isakmp enable command for
Cisco ASA Software releases prior to 8.4, and verifying that ikev1 is
enabled on the interface.
The following example shows IKEv1 enabled on the outside interface:
ciscoasa# show running-config crypto ikev1
crypto ikev1 enable outside
Note: IKEv1 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 IKE Daemon 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 IKE Daemon:
ciscoasa# show crashinfo
: Saved_Crash
Thread Name: IKE Daemon
.
.
.
Customers should contact their support organization if they suspect
active exploitation of this vulnerability to have the traceback decoded
to confirm whether the crash is due to this vulnerability.
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 Affected; migrate to 8.2(5.58) or later Affected; migrate to 8.2(5.58) or later
8.2 8.2(5.58) 8.2(5.58) and later
8.3 Affected; migrate to 8.4(7.29) or later Affected; migrate to 8.4(7.29) or later
8.4 8.4(7.29) 8.4(7.29)
8.5 Affected; migrate to 9.0(4.37) or later Affected; migrate to 9.0(4.37) or later
8.6 Affected; migrate to 9.0(4.37) or later Affected; migrate to 9.0(4.37) or later
8.7 8.7(1.17) 8.7(1.17) and later
9.0 9.0(4.37) 9.0(4.37) and later
9.1 9.1(6.8) 9.1(6.8) and later
9.2 9.2(4) 9.2(4) and later
9.3 9.3(3) 9.3(3.5) and later
9.4 Not affected 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-ike
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 standalone 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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