ESB-2019.0355 - [Cisco] Cisco Web Security Appliance: Unauthorised access - Remote/unauthenticated 2019-02-07

Printable version
PGP/GPG verifiable version

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA256

===========================================================================
             AUSCERT External Security Bulletin Redistribution

                               ESB-2019.0355
    Cisco Web Security Appliance Decryption Policy Bypass Vulnerability
                              7 February 2019

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

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

Product:           Cisco Web Security Appliance
Publisher:         Cisco Systems
Operating System:  Cisco
Impact/Access:     Unauthorised Access -- Remote/Unauthenticated
Resolution:        Patch/Upgrade
CVE Names:         CVE-2019-1672  

Original Bulletin: 
   https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20190206-wsa-bypass

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

Cisco Security Advisory

Cisco Web Security Appliance Decryption Policy Bypass Vulnerability

Advisory ID:      cisco-sa-20190206-wsa-bypass
First Published:  2019 February 6 16:00 GMT
Version 1.0:      Final
Workarounds:      No workarounds available
Cisco Bug IDs:    CSCvm91630
                  CVE-2019-1672
                  CWE-400
CVSS Score:       Base 5.8
CVSS:             3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N/E:X/RL:X/RC:X

Summary

  o
    A vulnerability in the Decryption Policy Default Action functionality of
    the Cisco Web Security Appliance (WSA) could allow an unauthenticated,
    remote attacker to bypass a configured drop policy and allow traffic onto
    the network that should have been denied.

    The vulnerability is due to the incorrect handling of SSL-encrypted traffic
    when Decrypt for End-User Notification is disabled in the configuration. An
    attacker could exploit this vulnerability by sending a SSL connection
    through the affected device. A successful exploit could allow the attacker
    to bypass a configured drop policy to block specific SSL connections.

    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-20190206-wsa-bypass

Affected Products

  o Vulnerable Products

    This vulnerability affects Cisco Web Security Appliance. For information
    about affected software releases, consult the Cisco bug ID(s) at the top of
    this advisory.

    Products Confirmed Not Vulnerable

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

Details

  o To determine if Decrypt for End-User Notification is Disabled on the WSA,
    an administrator can do the following:

      - Navigate to Security Service > HTTPS Proxy > Decrypt for End-User
        Notification.
      - Verify that the Decrypt for End-User Notification configuration setting
        is Disabled.

Workarounds

  o There are no workarounds that address this vulnerability.

Fixed Software

  o For information about fixed software releases, consult the Cisco bug ID(s)
    at the top of this advisory.

    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.

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-20190206-wsa-bypass

Revision History

  o
    +---------+---------------------------+---------+--------+-------------------+
    | Version |        Description        | Section | Status |       Date        |
    +---------+---------------------------+---------+--------+-------------------+
    | 1.0     | Initial public release.   | --       | Final  | 2019-February-06 |
    +---------+---------------------------+---------+--------+-------------------+

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

You have received this e-mail bulletin as a result of your organisation's
registration with AusCERT. The mailing list you are subscribed to is
maintained within your organisation, so if you do not wish to continue
receiving these bulletins you should contact your local IT manager. If
you do not know who that is, please send an email to auscert@auscert.org.au
and we will forward your request to the appropriate person.

NOTE: Third Party Rights
This security bulletin is provided as a service to AusCERT's members.  As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to follow or act on information or advice
contained in this security bulletin is the responsibility of each user or
organisation, and should be considered in accordance with your organisation's
site policies and procedures. AusCERT takes no responsibility for consequences
which may arise from following or acting on information or advice contained in
this security bulletin.

NOTE: This is only the original release of the security bulletin.  It may
not be updated when updates to the original are made.  If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the author's website to ensure that the information is still current.

Contact information for the authors of the original document is included
in the Security Bulletin above.  If you have any questions or need further
information, please contact them directly.

Previous advisories and external security bulletins can be retrieved from:

        https://www.auscert.org.au/bulletins/

===========================================================================
Australian Computer Emergency Response Team
The University of Queensland
Brisbane
Qld 4072

Internet Email: auscert@auscert.org.au
Facsimile:      (07) 3365 7031
Telephone:      (07) 3365 4417 (International: +61 7 3365 4417)
                AusCERT personnel answer during Queensland business hours
                which are GMT+10:00 (AEST).
                On call after hours for member emergencies only.
===========================================================================
-----BEGIN PGP SIGNATURE-----
Comment: http://www.auscert.org.au/render.html?it=1967
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=TbS5
-----END PGP SIGNATURE-----

« Back to bulletins