Summary

• A vulnerability in the content filtering functionality of Cisco AsyncOS Software for Cisco Email Security Appliances could allow an unauthenticated, remote attacker to bypass user filters that are configured for an affected device.
  
  The vulnerability is due to improper filtering of certain TAR format files that are attached to email messages. An attacker could exploit this vulnerability by sending an email message that has a crafted TAR file attachment through an affected device. A successful exploit could allow the attacker to bypass user filters that are configured for the device.
  
  There are no workarounds that address this vulnerability.
  
  This advisory is available at the following link:
  
  https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20161207-esa

Affected Products

• Vulnerable Products

  This vulnerability affects all releases prior to the first fixed release of Cisco AsyncOS Software for both virtual and hardware versions of the Cisco Email Security Appliances (ESAs) that are configured to use message or content filters that scan incoming email attachments.
   

  For example, the following content filter could be configured for an ESA:

  attachment-filename == "vulnerability"
  Action: drop

  To determine which release of Cisco AsyncOS Software is running on an ESA, administrators can use the version command in the ESA command-line interface (CLI). The following example shows the output of the version command for an ESA running Cisco AsyncOS Software Release 8.5.7-044:

  ciscoesa> version
  
  Current Version
  ===============
  Product: Cisco IronPort X1070 Messaging Gateway(tm) Appliance
  Model: X1070
  Version: 8.5.7-044
  .
  .
  .

  Note that Cisco provides regular maintenance of products in the Cisco Cloud Email Security (CES) service solution, which includes Cisco Email Security Appliances and Cisco Content Security Management Appliances. Customers can also request a software upgrade by contacting Cisco CES support.

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

Workarounds

• There are no workarounds that address this vulnerability.

Fixed Software

• For information about fixed software releases, consult the Cisco bug IDs 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

• 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 support case.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20161207-esa

Revision History

• Version	Description	Section	Status	Date
  2.0	Removed association to bug CSCvb06764. Removed Web Security Appliance from Summary and Vulnerable Products. Added Content Security Management Appliance and Web Security Appliance to Products Confirmed Not Vulnerable.	Summary, Vulnerable Products, and Products Confirmed Not Vulnerable	Final	2016-December-07
  1.0	Initial public release.	—	Final	2016-December-07

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