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AUSCERT External Security Bulletin Redistribution
Cisco Email Security Appliance Malformed EML Attachment
7 September 2017
AusCERT Security Bulletin Summary
Product: Cisco Email Security Appliance
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Reduced Security -- Remote/Unauthenticated
CVE Names: CVE-2017-12218
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Cisco Email Security Appliance Malformed EML Attachment Bypass Vulnerability
Advisory ID: cisco-sa-20170906-esa
First Published: 2017 September 6 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs:
Base 5.8 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N/E:X/RL:X/RC:X
A vulnerability in the malware detection functionality within Advanced Malware
Protection (AMP) of Cisco AsyncOS Software for Cisco Email Security Appliances
(ESAs) could allow an unauthenticated, remote attacker to cause an email
attachment containing malware to be delivered to the end user.
The vulnerability is due to the failure of AMP to scan certain EML attachments
that could contain malware. An attacker could exploit this vulnerability by
sending an email with a crafted EML attachment through the targeted device. A
successful exploit could allow the attacker to bypass the configured ESA email
message and content filtering and allow the malware to be delivered to the end
There are no workarounds that address this vulnerability.
This advisory is available at the following link:
This vulnerability affects Cisco AsyncOS Software for Cisco ESA, both virtual
and hardware appliances, that are configured with message or content filters
to scan incoming email attachments on the ESA. For information about affected
software releases, consult the Cisco bug ID(s) at the top of this advisory.
Products Confirmed Not Vulnerable
No other Cisco products are currently known to be affected by this
Cisco has confirmed that this vulnerability does not affect the following
Cisco Web Security Appliance, virtual and hardware versions
Cisco Content Security Management Appliance, virtual and hardware versions
There are no workarounds that address this vulnerability.
For information about fixed software releases, consult the Cisco bug ID(s) 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
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.
This vulnerability was found during resolution of a Cisco TAC Support case.
Version Description Section Status Date
1.0 Initial public release. - Final 2017-September-06
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FOR A PARTICULAR USE. YOUR USE OF THE INFORMATION ON THE DOCUMENT OR MATERIALS
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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.
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