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             AUSCERT External Security Bulletin Redistribution

                               ESB-2019.1779
                   Cisco IOS XR Software Vulnerabilities
                                17 May 2019

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

        AusCERT Security Bulletin Summary
        ---------------------------------

Product:           Cisco IOS XR Software
Publisher:         Cisco Systems
Operating System:  Cisco
Impact/Access:     Denial of Service -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2019-1849 CVE-2019-1846 

Original Bulletin: 
   https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190515-iosxr-evpn-dos
   https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190515-iosxr-mpls-dos

Comment: This bulletin contains two (2) Cisco Systems security advisories.

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

Cisco IOS XR Software BGP MPLS-Based EVPN Denial of Service Vulnerability

Priority:        High

Advisory ID:     cisco-sa-20190515-iosxr-evpn-dos

First Published: 2019 May 15 16:00 GMT

Version 1.0:     Final

Workarounds:     No workarounds availableCisco Bug IDs:   CSCvk35997

CVE-2019-1849    

CWE-754

CVSS Score:
7.4  AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X

Summary

  o A vulnerability in the Border Gateway Patrol (BGP) Multiprotocol Label
    Switching (MPLS)-based Ethernet VPN (EVPN) implementation of Cisco IOS XR
    Software could allow an unauthenticated, adjacent attacker to trigger a
    denial of service (DoS) condition on an affected device.

    The vulnerability is due to a logic error that occurs when the affected
    software processes specific EVPN routing information. An attacker could
    exploit this vulnerability by injecting malicious traffic patterns into the
    targeted EVPN network.

    A successful exploit could result in a crash of the l2vpn_mgr process on
    Provider Edge (PE) device members of the same EVPN instance (EVI). On each
    of the affected devices, a crash could lead to system instability and the
    inability to process or forward traffic through the device, resulting in a
    DoS condition that would require manual intervention to restore normal
    operating conditions.

    Cisco has released software updates that address this vulnerability. There
    are no workarounds that address this vulnerability.

    This advisory is available at the following link:
    https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
    cisco-sa-20190515-iosxr-evpn-dos

Affected Products

  o Vulnerable Products

    This vulnerability affects Cisco devices that are running a vulnerable
    release of Cisco IOS XR Software and are participating in a BGP MPLS-based
    EVI.

    Cisco has confirmed that this vulnerability affects both Cisco IOS XR
    32-bit Software and Cisco IOS XR 64-bit Software.

    For information about which Cisco IOS XR Software releases are vulnerable,
    see the Fixed Software section of this advisory.

    Determining Whether the Device Has a Vulnerable Configuration

    There are two methods for determining whether the device has a vulnerable
    configuration.

    Option 1: Using the show evpn evi | include EVPN command

    Administrators can use the show evpn evi | include EVPN command to
    determine whether the device is participating in a BGP MPLS-based EVI.

    The following example shows the output of the command for a device that is
    participating in a BGP MPLS-based EVI:

        RP/0/0/CPU0:Router#show evpn evi | i EVPN
        Tue May 14 09:40:09.277 EST

        VPN-ID     Encap     Bridge Domain                Type
        ---------- ------ ---------------------------- -------------------
        <VPN-ID>   MPLS     <BD-NAME>                      EVPN

    If this command does not exist, or if it produces an output that does not
    show the string EVPN within the Type column, the device is not affected by
    the vulnerability described in this advisory.

    Option 2: Using the show running-config formal l2vpn | include "l2vpn
    bridge group [^ ]+ bridge-domain [^ ]+ evi [0-9]+" command

    Administrators can use the show running-config formal l2vpn | include
    "l2vpn bridge group [^ ]+ bridge-domain [^ ]+ evi [0-9]+" command to
    determine whether the device is participating in a BGP MPLS-based EVI. The
    following example shows the output of the command for a device that is
    participating in a BGP MPLS-based EVI:

        RP/0/0/CPU0:Router#show running-config formal l2vpn | include "l2vpn bridge group [^ ]+ bridge-domain [^ ]+ evi [0-9]+"
        l2vpn bridge group  bridge-domain  evi

    An empty output of this command indicates that the device is not affected
    by the vulnerability described in this advisory.

    Note : Some hardware/software combinations may not support the show
    running-config formal command. In that case, use the verification step
    indicated in Option 1.

    Determining the Cisco IOS XR Software Release

    To determine which Cisco IOS XR Software release is running on a device and
    the name of the device on which it is running, administrators can log in to
    the device and use the show version command in the CLI. If the device is
    running Cisco IOS XR Software or similar text appears in the system banner.
    The location and name of the system image file that is currently running on
    the device appears next to the System image file is text. The name of the
    hardware product appears on the line after the name of the system image
    file.

    The following example shows the output of the show version command on a
    device that is running Cisco IOS XR Software Release 6.5.2:

        RP/0/RSP0/CPU0:ASR9001#show version
        Tue May 14 01:32:32.751 EST

        Cisco IOS XR Software, Version 6.5.2[Default]
        Copyright (c) 2019 by Cisco Systems, Inc.

        ROM: System Bootstrap, Version 2.04(20140227:092320) [ASR9K ROMMON],

        ASR9001 uptime is 6 hours, 17 minutes
        System image file is "bootflash:disk0/asr9k-os-mbi-5.3.4.sp4-1.0.0/0x100000/mbiasr9k-rp.vm"

        cisco ASR9K Series (P4040) processor with 8388608K bytes of memory.
        P4040 processor at 1500MHz, Revision 2.0
        ASR-9001 Chassis

        2 Management Ethernet
        8 TenGigE
        20 GigabitEthernet
        8 DWDM controller(s)
        8 WANPHY controller(s)
        44 GigabitEthernet/IEEE 802.3 interface(s)
        219k bytes of non-volatile configuration memory.
        2880M bytes of hard disk.
        3932144k bytes of disk0: (Sector size 512 bytes).

        Configuration register on node 0/RSP0/CPU0 is 0x2102

    Products Confirmed Not Vulnerable

    Only products listed in the Vulnerable Products section of this advisory
    are known to be affected by this vulnerability.

    No other Cisco products are currently known to be affected by this
    vulnerability.

    Cisco has confirmed that this vulnerability does not affect devices running
    Cisco IOS Software, Cisco IOS XE Software, or Cisco NX-OS Software.

Details

  o EVPN is a next-generation solution that provides Ethernet multipoint
    services over MPLS networks. In EVPN, customers' MAC addresses are used as
    routable addresses. PE devices participating in an EVI use Multiprotocol
    BGP (MP-BGP) as a route learning and distribution mechanism.

    The vulnerability is due to a logic error that occurs when the affected
    software processes specific MP-BGP EVPN update messages. An attacker that
    controls multiple Customer Edge (CE) devices could exploit this
    vulnerability by injecting malicious traffic patterns into the EVPN
    network. An exploit could cause the Provider Edge (PE) device to advertise
    specific MP-BGP EVPN update messages that could result in a crash of the
    l2vpn_mgr process on PE device members of the same EVI.

Indicators of Compromise

  o Exploitation of this vulnerability could cause the affected device to
    repeatedly generate an error message similar to the following:

        RP/0/RP0/CPU0:May 14 15:41:03.241 IST: syslog_dev[117]: l2vpn_mgr[1265] PID-8642:
        l2vpn/evpn/include/evpn_label_db_defs.h: 412 FALSE -- assertion failed

    Customers are advised to contact their support organization to review the
    error message and determine whether the device has been affected by
    exploitation of this vulnerability.

Workarounds

  o There are no workarounds that address this vulnerability.

Fixed Software

  o Cisco has released free software updates that address the vulnerability
    described in this advisory. Customers may only install and expect support
    for software versions and feature sets for which they have purchased a
    license. By installing, downloading, accessing, or otherwise using such
    software upgrades, customers agree to follow the terms of the Cisco
    software license:
    https://www.cisco.com/c/en/us/products/end-user-license-agreement.html

    Additionally, customers may only download software for which they have a
    valid license, procured from Cisco directly, or through a Cisco authorized
    reseller or partner. In most cases this will be a maintenance upgrade to
    software that was previously purchased. Free security software updates do
    not entitle customers to a new software license, additional software
    feature sets, or major revision upgrades.

    When considering software upgrades, customers are advised to regularly
    consult the advisories for Cisco products, which are available from the
    Cisco Security Advisories and Alerts page , to determine exposure and a
    complete upgrade solution.

    In all cases, customers should ensure that the devices to be upgraded
    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.

    Customers Without Service Contracts

    Customers who purchase directly from Cisco but do not hold a Cisco service
    contract and customers who make purchases through third-party vendors but
    are unsuccessful in obtaining fixed software through their point of sale
    should obtain upgrades by contacting the Cisco TAC:
    https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html

    Customers should have the product serial number available and be prepared
    to provide the URL of this advisory as evidence of entitlement to a free
    upgrade.

    Fixed Releases

    The following table lists major software release trains of Cisco IOS XR
    Software, indicates whether a release train is affected by the
    vulnerabilities described in this advisory, and the first minor release
    that includes the fix for these vulnerabilities, if applicable. Customers
    should migrate to an appropriate release as indicated in the following
    table:

    Software Train First Fixed Release Recommended Release
    4.3            Not vulnerable      Not vulnerable
    5.0            Not vulnerable      Not vulnerable
    5.1            Not vulnerable      Not vulnerable
    5.2            Not vulnerable      Not vulnerable
    5.3            Not vulnerable      Not vulnerable
    6.0            Not vulnerable      Not vulnerable
    6.1            6.5.3               6.5.3
    6.2            6.5.3               6.5.3
    6.3            6.3.3               6.3.3
    6.4            6.4.2               6.4.2
    6.5            6.5.2               6.5.3
    6.6            6.6.1               6.6.12

Exploitation and Public Announcements

  o 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

  o This vulnerability was found during internal security testing.

Cisco Security Vulnerability Policy

  o To learn about Cisco security vulnerability disclosure policies and
    publications, see the Security Vulnerability Policy . This document also
    contains instructions for obtaining fixed software and receiving security
    vulnerability information from Cisco.

URL

  o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
    cisco-sa-20190515-iosxr-evpn-dos

Revision History

  o +----------+---------------------------+----------+--------+--------------+
    | Version  |        Description        | Section  | Status |     Date     |
    +----------+---------------------------+----------+--------+--------------+
    | 1.0      | Initial public release.   | -        | Final  | 2019-May-15  |
    +----------+---------------------------+----------+--------+--------------+

- -------------------------------------------------------------------------------

Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers
MPLS OAM Denial of Service Vulnerability

Priority:        High

Advisory ID:     cisco-sa-20190515-iosxr-mpls-dos

First Published: 2019 May 15 16:00 GMT

Version 1.0:     Final

Workarounds:     No workarounds available

Cisco Bug IDs:   CSCvk63685

CVE-2019-1846    

CWE-20

CVSS Score:
7.4  AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X

Summary

  o 
    A vulnerability in the Multiprotocol Label Switching (MPLS) Operations,
    Administration, and Maintenance (OAM) implementation of Cisco IOS XR
    Software for Cisco ASR 9000 Series Aggregation Services Routers could allow
    an unauthenticated, adjacent attacker to trigger a denial of service (DoS)
    condition on an affected device.

    The vulnerability is due to the incorrect handling of certain MPLS OAM
    packets. An attacker could exploit this vulnerability by sending malicious
    MPLS OAM packets to an affected device. A successful exploit could allow
    the attacker to cause the lspv_server process to crash. The crash could
    lead to system instability and the inability to process or forward traffic
    though the device, resulting in a DoS condition that require manual
    intervention to restore normal operating conditions.

    Cisco has released software updates that address this vulnerability. There
    are no workarounds that address this vulnerability.

    This advisory is available at the following link:
    https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
    cisco-sa-20190515-iosxr-mpls-dos

Affected Products

  o Vulnerable Products

    This vulnerability affects Cisco Aggregation Services Router (ASR) 9000
    Series when the following conditions are met:

       The router is running Cisco IOS XR Software Release 5.3.3 Service Pack
        10.
       The router has the MPLS OAM feature configured.

    For information about which Cisco IOS XR Software releases are vulnerable,
    see the Fixed Software section of this advisory.

    Determining Whether MPLS OAM Is Configured

    Administrators can use the show running-config mpls oam command to
    determine whether MPLS OAM is enabled. The following example shows the
    output of the command for a device that has the MPLS OAM feature enabled:

        RP/0/RSP0/CPU0:ASR9001#show running-config mpls oam
        Tue Feb 19 12:45:37.011 UTC
        mpls oam

    An empty output of this command indicates that the device is not affected
    by the vulnerability described in this advisory.

    Determining the Cisco IOS XR Software Release

    To determine which Cisco IOS XR Software release is running on a device and
    the name of the device on which it is running, administrators can log in to
    the device and use the show version command in the CLI. If the device is
    running Cisco IOS XR Software, Cisco IOS XR Software or similar text
    appears in the system banner. The location and name of the system image
    file that is currently running on the device appears next to the System
    image file is text. The name of the hardware product appears on the line
    after the name of the system image file.

    The following example shows the output of the show version command on a
    device that is running Cisco IOS XR Software release 5.3.3 Service Pack 10 
    :

        RP/0/RSP0/CPU0:ASR9001#show version
        Wed Jan 24 01:32:32.751 EST

        Cisco IOS XR Software, Version 5.3.3[Default]
        Copyright (c) 2017 by Cisco Systems, Inc.

        ROM: System Bootstrap, Version 2.04(20140227:092320) [ASR9K ROMMON],

        ASR9001 uptime is 6 hours, 17 minutes
        System image file is "bootflash:disk0/asr9k-os-mbi-5.3.3.sp10-1.0.0/0x100000/mbiasr9k-rp.vm"

        cisco ASR9K Series (P4040) processor with 8388608K bytes of memory.
        P4040 processor at 1500MHz, Revision 2.0
        ASR-9001 Chassis

        2 Management Ethernet
        8 TenGigE
        20 GigabitEthernet
        8 DWDM controller(s)
        8 WANPHY controller(s)
        44 GigabitEthernet/IEEE 802.3 interface(s)
        219k bytes of non-volatile configuration memory.
        2880M bytes of hard disk.
        3932144k bytes of disk0: (Sector size 512 bytes).

        Configuration register on node 0/RSP0/CPU0 is 0x2102

    Products Confirmed Not Vulnerable

    Only products listed in the Vulnerable Products section of this advisory
    are known to be affected by this vulnerability.

    Cisco has determined that this vulnerability does not affect Cisco
    Aggregation Services Router (ASR) 9000 Series that are not running Cisco
    IOS XR Software Release 5.3.3 Service Pack 10 or that have not enabled the
    MPLS OAM feature. Note : The MPLS OAM feature is not enabled by default on
    Cisco XR Software.

    No other devices running Cisco IOS XR Software are affected. Cisco has also
    confirmed that this vulnerability does not affect devices running Cisco IOS
    Software, Cisco IOS XE Software, or Cisco NX-OS Software.

Details

  o The MPLS OAM feature helps service providers monitor label-switched paths
    (LSPs) and quickly isolate MPLS forwarding problems to assist with fault
    detection and troubleshooting in an MPLS network. The vulnerability is due
    to the incorrect handling of certain MPLS OAM packets. An attacker could
    exploit this vulnerability by sending malicious MPLS OAM packets to an
    affected device. To exploit this vulnerability, an attacker must have
    access to the same MPLS domain as the targeted device, which must be
    configured to process MPLS OAM packets. An exploitation of this
    vulnerability could cause the lspv_server process to crash, which could
    result in a DoS condition requiring manual intervention to recover.

Indicators of Compromise

  o Exploitation of this vulnerability could cause the affected device to
    generate an error message similar to the following:

        #RP/0/RSP0/CPU0:May  14 01:44:57.911 : dumper[60]: %OS-DUMPER-7 DUMP_REQUEST : Dump request for process pkg/bin/lspv_server
         RP/0/RSP0/CPU0:May  14 01:44:57.913 : dumper[60]: %OS-DUMPER-7-DUMP_ATTRIBUTE : Dump request with attribute 7 for process pkg/bin/lspv_server
         RP/0/RSP0/CPU0:May  14 01:44:57.913 : dumper[60]: %OS-DUMPER-4-CRASH_INFO : Crashed pid = 561506 (pkg/bin/lspv_server)

    Customers are advised to contact their support organization to review the
    error message and determine whether the device has been affected by
    exploitation of this vulnerability.

Workarounds

  o There are no workarounds that address this vulnerability.

    Disabling the MPLS OAM feature eliminates the exploit vector.
    Administrators can disable the MPLS OAM feature by using the no mpls oam 
    command in global configuration mode. This action may be a suitable
    mitigation until devices that are affected by this vulnerability can be
    upgraded.

Fixed Software

  o Cisco has released free software updates that address the vulnerability
    described in this advisory. Customers may only install and expect support
    for software versions and feature sets for which they have purchased a
    license. By installing, downloading, accessing, or otherwise using such
    software upgrades, customers agree to follow the terms of the Cisco
    software license:
    https://www.cisco.com/c/en/us/products/end-user-license-agreement.html

    Additionally, customers may only download software for which they have a
    valid license, procured from Cisco directly, or through a Cisco authorized
    reseller or partner. In most cases this will be a maintenance upgrade to
    software that was previously purchased. Free security software updates do
    not entitle customers to a new software license, additional software
    feature sets, or major revision upgrades.

    When considering software upgrades, customers are advised to regularly
    consult the advisories for Cisco products, which are available from the
    Cisco Security Advisories and Alerts page , to determine exposure and a
    complete upgrade solution.

    In all cases, customers should ensure that the devices to be upgraded
    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.

    Customers Without Service Contracts

    Customers who purchase directly from Cisco but do not hold a Cisco service
    contract and customers who make purchases through third-party vendors but
    are unsuccessful in obtaining fixed software through their point of sale
    should obtain upgrades by contacting the Cisco TAC:
    https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html

    Customers should have the product serial number available and be prepared
    to provide the URL of this advisory as evidence of entitlement to a free
    upgrade.

    Fixed Releases

    Cisco has released a software maintenance upgrade (SMU) for Cisco
    Aggregation Services Router (ASR) 9000 Series that addresses this
    vulnerability. The fix has also been incorporated into Service Pack 11 for
    Cisco IOS XR Software Release 5.3.3.

    IOS XR Release SMU ID  ASR 9000 SMU Name
    5.3.3          AA14582 asr9k-px-5.3.3.CSCvk63685

    The SMU/service pack can be downloaded from the Software Center on
    Cisco.com.

Exploitation and Public Announcements

  o 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

  o This vulnerability was found during the resolution of a Cisco TAC support
    case.

Cisco Security Vulnerability Policy

  o To learn about Cisco security vulnerability disclosure policies and
    publications, see the Security Vulnerability Policy . This document also
    contains instructions for obtaining fixed software and receiving security
    vulnerability information from Cisco.

URL

  o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
    cisco-sa-20190515-iosxr-mpls-dos

Revision History

  o +----------+---------------------------+----------+--------+--------------+
    | Version  |        Description        | Section  | Status |     Date     |
    +----------+---------------------------+----------+--------+--------------+
    | 1.0      | Initial public release.   | -        | Final  | 2019-May-15  |
    +----------+---------------------------+----------+--------+--------------+

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

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