Wednesday, May 1, 2019

Cisco Web Security Appliance Malformed Request Denial of Service Vulnerability

High
Advisory ID:
cisco-sa-20190501-wsa-dos
First Published:
2019 May 1 16:00 GMT
Version 1.0:
Workarounds:
No workarounds available
Cisco Bug IDs:
CVE-2019-1817
CWE-20
CVSS Score:
Base 8.6Click Icon to Copy Verbose Score
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
CVE-2019-1817
CWE-20

Summary

  • A vulnerability in the web proxy functionality of Cisco AsyncOS Software for Cisco Web Security Appliance could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device.

    The vulnerability is due to improper validation of HTTP and HTTPS requests. An attacker could exploit this vulnerability by sending a malformed HTTP or HTTPS request to an affected device. An exploit could allow the attacker to cause a restart of the web proxy process, resulting in a temporary DoS condition.

    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-20190501-wsa-dos

Affected Products

  • Vulnerable Products

    This vulnerability affects Cisco AsyncOS Software for Cisco Web Security Appliance, both virtual and hardware appliances. For more information about which Cisco AsyncOS Software releases are vulnerable, see the Fixed Software section 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.

    Cisco has confirmed that this vulnerability does not affect the following Cisco products:

    • Email Security Appliance (ESA), both virtual and hardware appliances
    • Security Management Appliance (SMA), both virtual and hardware appliances

Indicators of Compromise

  • Upon successful exploitation of this vulnerability, the WSA could write out a core file for the main proxy process. Contact the Cisco Technical Assistance Center (TAC) to review the core file and confirm if the core file shows that the device has been compromised by this vulnerability.

Workarounds

  • There are no workarounds that address this vulnerability.

Fixed Software

  • 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

    Customers are advised to upgrade to an appropriate release as indicated in the following table:

     Cisco AsyncOS Software Major Release  First Fixed Release
     10.1  Not vulnerable
     10.5  Not vulnerable
     11.5  11.5.2-020
     11.7  11.7.0-406

    In most cases, the software can be upgraded over the network by using the System Upgrade options in the web interface of the WSA. To upgrade a device by using the web interface:

    1. Choose System Administration > System Upgrade.
    2. Click Upgrade Options.
    3. Choose Download and Install.
    4. Choose the release to upgrade to.
    5. In the Upgrade Preparation area, choose the appropriate options.
    6. Click Proceed to begin the upgrade. A progress bar displays the status of the upgrade.

    After the upgrade is complete, the device reboots.

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 the resolution of a Cisco TAC support case.

Cisco Security Vulnerability Policy

  • 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.

Subscribe to Cisco Security Notifications

URL

Revision History

  • Version Description Section Status Date
    1.0 Initial public release. — Final 2019-May-01
    Show Less

Cisco Security Vulnerability Policy

  • 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.

Subscribe to Cisco Security Notifications



from Cisco Security Advisory http://bit.ly/2ZKArY1
Posted by at

No comments:

Post a Comment

Note: Only a member of this blog may post a comment.

Subscribe to: Post Comments (Atom)