Cisco Web Security Appliance Command Injection and Privilege Escalation Vulnerability

Summary

• A vulnerability in the web interface of the Cisco Web Security Appliance (WSA) could allow an authenticated, remote attacker to perform command injection and elevate privileges to root. The attacker must authenticate with valid administrator credentials.
  
  The vulnerability is due to insufficient validation of user-supplied input on the web interface. An attacker could exploit this vulnerability by authenticating to the affected device and performing command injection over the web interface. An exploit could allow the attacker to elevate privileges from administrator to root.
  
  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-20170719-wsa1

Affected Products

• Vulnerable Products

  This vulnerability affects certain releases of Cisco AsyncOS Software 10.0 and later for WSA on both virtual and hardware appliances. For additional information about affected and fixed software releases, see the Fixed Software section of this advisory.
  
  To determine whether a vulnerable release of Cisco AsyncOS Software is running on a Cisco WSA, administrators can use the version command in the WSA CLI. The following example shows the results for an appliance running Cisco AsyncOS Software Release 10.1.0-204:
  

  ciscowsa> version
  
  Current Version
  ===============
  Product: Cisco S370 Web Security Appliance
  Model: S370
  Version: 10.1.0-204
  Build Date: 2016-12-21
  .
  .
  .

  While logged in to the web GUI, administrators can view the Current AsyncOS Version under System Administration > System Upgrade.

  Products Confirmed Not Vulnerable

  No other Cisco products are currently known to be affected by this vulnerability.
  
  Cisco has confirmed that this vulnerability does not affect the following products:
  

  • Cisco Email Security Appliance, virtual and hardware versions
  • Cisco Content Security Management Appliance, virtual and hardware versions

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: http://www.cisco.com/en/US/docs/general/warranty/English/EU1KEN_.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: http://www.cisco.com/en/US/support/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 should upgrade to an appropriate release as indicated in the following table:
  
  

  Cisco AsyncOS for Web Software Major Release	First Fixed Release
  Prior to 10.0	Not affected
  10.0	Affected; migrate to 10.1.1-235
  10.1	10.1.1-235
  10.5	10.5.1-270
  11.0	Affected; migrate to the upcoming 11.5 release

  
  In most cases, Cisco WSA can be updated over the network by using the System Upgrade options in the System Administration GUI. Perform the following steps to upgrade a device by using the System Administration GUI:
  

  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 and reported to Cisco by Daniel Jensen from Security-Assessment.com.

URL

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170719-wsa1

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	?	Interim	2017-July-19

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