Operating System:

[Cisco]

Published:

22 October 2015

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             AUSCERT External Security Bulletin Redistribution

                               ESB-2015.2664
       Cisco ASA Software VPN ISAKMP Denial of Service Vulnerability
                              22 October 2015

===========================================================================

        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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