AV:N/AC:L/Au:N/C:P/I:N/A:N/E:F/RL:OF/RC:C
-
A vulnerability in the email filtering functionality of Cisco AsyncOS Software for Cisco Email Security Appliances could allow an unauthenticated, remote attacker to bypass Advanced Malware Protection (AMP) filters that are configured for an affected device.
The vulnerability is due to improper error handling when malformed Multipurpose Internet Mail Extensions (MIME) headers are present in an email attachment that is sent through an affected device. An attacker could exploit this vulnerability by sending an email message that has a crafted, MIME-encoded file attachment through an affected device. A successful exploit could allow the attacker to bypass AMP filter configurations 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-20161116-esa2
-
Vulnerable Products
This vulnerability affects all releases prior to the first fixed release of Cisco AsyncOS Software for both virtual and hardware versions of Cisco Email Security Appliances, if the AMP feature is configured to scan incoming email attachments.
To determine whether AMP is configured on a Cisco Email Security Appliance (ESA), administrators can use the Cisco AsyncOS System Administration GUI or the command-line interface (CLI).
In the System Administration GUI, choose Security Services > File Reputation and Analysis, and then check the setting for the File Reputation option.
In the CLI, issue the ampconfig command and check the value of the File Reputation field in the command output. The following example shows the output of the ampconfig command for an ESA that has AMP configured to scan incoming email attachments:ciscoesa> ampconfig File Reputation: Enabled File Analysis: Enabled File types selected for File Analysis: Microsoft Windows / DOS Executable Appliance Group ID/Name: Not part of any group yet
ciscoesa> version Current Version =============== Product: Cisco IronPort X1070 Messaging Gateway(tm) Appliance Model: X1070 Version: 8.5.7-044 . . .
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
-
Exploitation of this vulnerability could prevent the AMP feature from detecting a malformed MIME attachment as possible malware. The system log file may contain the following log entry:
Info: MID 2612684 AMP file reputation verdict : CLEAN
-
There are no workarounds that address this vulnerability.
-
For information about fixed software releases, consult the Cisco bug ID 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.
-
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.
-
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.
-
Version Description Section Status Date 1.0 Initial public release. — Final 2016-November-16
-
THIS DOCUMENT IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS LINKED FROM THE DOCUMENT IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS DOCUMENT AT ANY TIME.
A standalone copy or paraphrase of the text of this document that omits the distribution URL is an uncontrolled copy and may lack important information or contain factual errors. The information in this document is intended for end users of Cisco products.