Summary

• A vulnerability in the configured security policies, including drop email filtering, in Cisco AsyncOS for Cisco Email Security Appliance (ESA) could allow an unauthenticated, remote attacker to bypass a configured drop filter by using an email with a corrupted attachment.
  
  The vulnerability is due to improper error handling. An attacker could exploit this vulnerability by sending an email message with a corrupted attachment. A successful exploit could allow the attacker to bypass a configured drop filter.
  
  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://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20161026-esa5

Affected Products

• Vulnerable Products

  Cisco Email Security Appliance (ESA) software is vulnerable. Cisco provides information about affected releases in Cisco bugs, which are accessible through the Cisco Bug Search Tool.
  
  To determine which release of Cisco AsyncOS Software is running on an ESA, administrators can use the version command in the 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.
  
  The following products are not vulnerable:

  • Security Mail Appliance, both virtual and hardware versions
  • Web Security Appliance, both virtual and hardware versions

Workarounds

• There are no workarounds that address this vulnerability.

Fixed Software

• Cisco provides information about fixed software in Cisco bugs, which are accessible through the Cisco Bug Search Tool.
  
  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 resolution of a support case.

URL

• https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20161026-esa5

Revision History

• Version	Description	Section	Status	Date
  1.0	Initial public release.	—	Final	2016-October-26

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