Operating System:

[Cisco]

Published:

28 August 2020

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             AUSCERT External Security Bulletin Redistribution

                              ESB-2020.2522.5
  Cisco Adaptive Security Appliance Software and Firepower Threat Defense
       Software Web Services Read-Only Path Traversal Vulnerability
                              28 August 2020

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

Product:           Cisco Adaptive Security Appliance Software
                   Cisco Firepower Threat Defence
Publisher:         Cisco Systems
Operating System:  Cisco
Impact/Access:     Access Confidential Data -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2020-3452  

Original Bulletin: 
   https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ro-path-KJuQhB86

Revision History:  August 28 2020: Vendor clarified that VPN user credentials
                                   aren't exposed
                   July 29 2020:   Vendor added more detail on potential impact 
                                   within summary section
                   July 27 2020:   Setting ALERT flag for public exploitation attempts
                   July 24 2020:   Vendor included information on availability of 
                                   public exploit code and mitigation details
                   July 23 2020:   Initial Release

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

Cisco Adaptive Security Appliance Software and Firepower Threat Defense
Software Web Services Read-Only Path Traversal Vulnerability

Priority:        High
Advisory ID:     cisco-sa-asaftd-ro-path-KJuQhB86
First Published: 2020 July 22 16:00 GMT
Last Updated:    2020 August 27 14:33 GMT
Version 1.5:     Final
Workarounds:     No workarounds available
Cisco Bug IDs:   CSCvt03598

CVE-2020-3452
CWE-20

Summary

  o A vulnerability in the web services interface of Cisco Adaptive Security
    Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software
    could allow an unauthenticated, remote attacker to conduct directory
    traversal attacks and read sensitive files on a targeted system.

    The vulnerability is due to a lack of proper input validation of URLs in
    HTTP requests processed by an affected device. An attacker could exploit
    this vulnerability by sending a crafted HTTP request containing directory
    traversal character sequences to an affected device. A successful exploit
    could allow the attacker to view arbitrary files within the web services
    file system on the targeted device. As an example , this could allow an
    attacker to impersonate another VPN user and establish a Clientless SSL VPN
    or AnyConnect VPN session to the device as that user.

    The web services file system is enabled when the affected device is
    configured with either WebVPN or AnyConnect features. This vulnerability
    cannot be used to obtain access to ASA or FTD system files, underlying
    operating system (OS) files, or VPN user login credentials.

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

    Note: Cisco has become aware of the availability of public exploit code and
    active exploitation of the vulnerability that is described in this
    advisory. Cisco encourages customers with affected products to upgrade to a
    fixed release as soon as possible.

    This advisory is available at the following link:
    https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
    cisco-sa-asaftd-ro-path-KJuQhB86

Affected Products

  o Vulnerable Products

    This vulnerability affects Cisco products if they are running a vulnerable
    release of Cisco ASA Software or Cisco FTD Software with a vulnerable
    AnyConnect or WebVPN configuration.

    ASA Software

    In the following table, the left column lists the Cisco ASA features that
    are vulnerable. The right column indicates the basic configuration for the
    feature from the show running-config CLI command. If the device is
    configured for one of these features, it is vulnerable.

    Cisco ASA                       Vulnerable Configuration
     Feature
    AnyConnect
    IKEv2
    Remote     crypto ikev2 enable <interface_name> client-services port <port #>
    Access
    (with
    client
    services)
    AnyConnect webvpn
    SSL VPN     enable <interface_name>

    Clientless webvpn
    SSL VPN     enable <interface_name>

    FTD Software

    In the following table, the left column lists the Cisco FTD features that
    are vulnerable. The right column indicates the basic configuration for the
    feature from the show running-config CLI command. If the device is
    configured for one of these features, it is vulnerable.

    On devices running Cisco FTD Software, the show running-config command is
    available from Diagnostic CLI mode only. To enter Diagnostic CLI mode, use
    the system support diagnostic-cli command in the regular Firepower Threat
    Defense CLI.

    Cisco FTD                       Vulnerable Configuration
     Feature
    AnyConnect
    IKEv2
    Remote
    Access     crypto ikev2 enable <interface_name> client-services port <port #>
    (with
    client
    services)
    ^1,2
    AnyConnect webvpn
    SSL VPN ^   enable <interface_name>
    1,2

    1. Remote Access VPN features are enabled via Devices > VPN > Remote Access
    in the Cisco Firepower Management Center (FMC) or via Device > Remote
    Access VPN in Cisco Firepower Device Manager (FDM).
    2. Remote Access VPN features were first supported as of Cisco FTD Software
    Release 6.2.2.

    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 confirmed that this vulnerability does not affect Cisco Firepower
    Management Center (FMC) Software.

Details

  o The attacker can view files within the web services file system only. The
    web services file system is enabled for the WebVPN and AnyConnect features
    outlined in the Vulnerable Products section of this advisory; therefore,
    this vulnerability does not apply to the ASA and FTD system files or
    underlying operating system (OS) files. The web services files that the
    attacker can view may have information such as WebVPN configuration,
    bookmarks, web cookies, partial web content, and HTTP URLs.

Workarounds

  o There are no workarounds that address this vulnerability.

    To help detect and/or block attempts to exploit the vulnerability that is
    described in this advisory, customers who use the SSL Decryption feature
    for affected traffic on Cisco Firepower sensors can enable Snort rules
    54598 through 54601, from SRU number 2020-07-22-001 , by using the Cisco
    Firepower Management Center.

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 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

    In the following table(s), the left column lists Cisco software releases.
    The right column indicates whether a release is affected by the
    vulnerability described in this advisory and the first release that
    includes the fix for this vulnerability.

    Cisco ASA Software

    Cisco ASA Software Release   First Fixed Release for This Vulnerability
    Earlier than 9.6 ^1          Migrate to a fixed release.
    9.6                          9.6.4.42
    9.7 ^1                       Migrate to a fixed release.
    9.8                          9.8.4.20
    9.9                          9.9.2.74
    9.10                         9.10.1.42
    9.12                         9.12.3.12
    9.13                         9.13.1.10
    9.14                         9.14.1.10

    1. Cisco ASA Software releases 9.5 and earlier, as well as Release 9.7,
    have reached end of software maintenance. Customers are advised to migrate
    to a supported release that includes the fix for this vulnerability.

    Cisco FTD Software

    Cisco FTD Software Release   First Fixed Release for This Vulnerability
    Earlier than 6.2.2           Not vulnerable.
    6.2.2                        Migrate to a fixed release.
    6.2.3                        6.2.3.16
                                 Migrate to 6.4.0.9 + Hot Fix or to 6.6.0.1
                                 or
    6.3.0                        6.3.0.5 + Hot Fix ^1
                                 or
                                 6.3.0.6 (Fall 2020)
                                 6.4.0.9 + Hot Fix ^1
    6.4.0                        or
                                 6.4.0.10 (Fall 2020)
                                 Migrate to 6.6.0.1
                                 or
    6.5.0                        6.5.0.4 + Hot Fix ^1
                                 or
                                 6.5.0.5 (Fall 2020)
    6.6.0                        6.6.0.1

    1. For hot fix details please refer to the table below.

    Cisco FTD Software Hot Fix Details

    Cisco FTD Software       Hot Fix File Names
    Release
                             Cisco_FTD_Hotfix_AV-6.3.0.6-3.sh.REL.tar
    6.3.0.5                  Cisco_FTD_SSP_Hotfix_AV-6.3.0.6-3.sh.REL.tar
                             Cisco_FTD_SSP_FP2K_Hotfix_AV-6.3.0.6-3.sh.REL.tar
                             Cisco_FTD_Hotfix_BM-6.4.0.10-2.sh.REL.tar
    6.4.0.9                  Cisco_FTD_SSP_FP1K_Hotfix_BM-6.4.0.10-2.sh.REL.tar
                             Cisco_FTD_SSP_FP2K_Hotfix_BM-6.4.0.10-2.sh.REL.tar
                             Cisco_FTD_SSP_Hotfix_BM-6.4.0.10-2.sh.REL.tar
                             Cisco_FTD_Hotfix_O-6.5.0.5-3.sh.REL.tar
    6.5.0.4                  Cisco_FTD_SSP_FP2K_Hotfix_O-6.5.0.5-3.sh.REL.tar
                             Cisco_FTD_SSP_FP1K_Hotfix_O-6.5.0.5-3.sh.REL.tar
                             Cisco_FTD_SSP_Hotfix_O-6.5.0.5-3.sh.REL.tar

    To upgrade to a fixed release of Cisco FTD Software, customers can do one
    of the following:

       For devices that are managed by using Cisco Firepower Management Center
        (FMC), use the FMC interface to install the upgrade. After installation
        is complete, reapply the access control policy.
       For devices that are managed by using Cisco Firepower Device Manager
        (FDM), use the FDM interface to install the upgrade. After installation
        is complete, reapply the access control policy.

Exploitation and Public Announcements

  o The Cisco Product Security Incident Response Team (PSIRT) is aware of the
    existence of public exploit code and active exploitation of the
    vulnerability that is described in this advisory.

Source

  o Cisco would like to thank Mikhail Klyuchnikov of Positive Technologies and
    Abdulrahman Nour and Ahmed Aboul-Ela of RedForce for independently
    reporting this vulnerability.

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.

Action Links for This Advisory

  o Snort Rule 54598
    Snort Rule 54599
    Snort Rule 54600
    Snort Rule 54601

URL

  o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
    cisco-sa-asaftd-ro-path-KJuQhB86

Revision History

  o +---------+------------------------+---------------+--------+-------------+
    | Version |      Description       |    Section    | Status |    Date     |
    +---------+------------------------+---------------+--------+-------------+
    |         | Clarified that VPN     |               |        |             |
    |         | user login credentials | Summary,      |        |             |
    | 1.5     | are not exposed;       | Fixed         | Final  | 2020-AUG-27 |
    |         | updated availability   | Software      |        |             |
    |         | of fixed software.     |               |        |             |
    +---------+------------------------+---------------+--------+-------------+
    | 1.4     | Added more detail on   | Summary       | Final  | 2020-JUL-28 |
    |         | potential impact.      |               |        |             |
    +---------+------------------------+---------------+--------+-------------+
    | 1.3     | Added mitigation       | Workarounds   | Final  | 2020-JUL-23 |
    |         | details.               |               |        |             |
    +---------+------------------------+---------------+--------+-------------+
    |         |                        | Summary,      |        |             |
    | 1.2     | Updated to alert about | Exploitation  | Final  | 2020-JUL-23 |
    |         | active exploitation.   | and Public    |        |             |
    |         |                        | Announcements |        |             |
    +---------+------------------------+---------------+--------+-------------+
    |         | Updated to indicate    | Exploitation  |        |             |
    | 1.1     | the availability of    | and Public    | Final  | 2020-JUL-23 |
    |         | public exploit code.   | Announcements |        |             |
    +---------+------------------------+---------------+--------+-------------+
    | 1.0     | Initial public         | -             | Final  | 2020-JUL-22 |
    |         | release.               |               |        |             |
    +---------+------------------------+---------------+--------+-------------+

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