CVE-2017-12353 : Security Advisory and Response

A weakness has been identified in the Multipurpose Internet Mail Extensions (MIME) scanner of Cisco AsyncOS Software used for Cisco Email Security Appliances (ESA). This vulnerability could potentially allow an unauthorized attacker to bypass user filters on the device by exploiting a malformed MIME header in an email attachment.

Understanding CVE-2017-12353

This CVE involves a vulnerability in the MIME scanner of Cisco Email Security Appliances that could be exploited to circumvent user filters on the device.

What is CVE-2017-12353?

The vulnerability in the MIME scanner of Cisco AsyncOS Software for Cisco Email Security Appliances allows attackers to bypass configured user filters by sending emails with crafted MIME attachments.

The Impact of CVE-2017-12353

Unauthorized attackers could exploit this vulnerability to bypass user filters on the device.
Successful exploitation could lead to the ability to discard emails by bypassing configured filters.

Technical Details of CVE-2017-12353

This section provides technical details about the vulnerability.

Vulnerability Description

The vulnerability arises from the improper handling of a malformed MIME header found in an email attachment, allowing attackers to bypass user filters on the device.

Affected Systems and Versions

Product: Cisco Email Security Appliance
Version: Cisco Email Security Appliance

Exploitation Mechanism

Attackers exploit the vulnerability by sending emails containing specifically crafted MIME attachments.
The malformed MIME headers may not adhere to RFC regulations but can still bypass the device's filtering mechanism.

Mitigation and Prevention

Steps to address and prevent the CVE-2017-12353 vulnerability.

Immediate Steps to Take

Apply patches and updates provided by Cisco to address the vulnerability.
Monitor email attachments for suspicious MIME headers.

Long-Term Security Practices

Regularly update and patch email security appliances.
Educate users on identifying and handling suspicious email attachments.

Patching and Updates

Stay informed about security advisories from Cisco.
Implement a robust email security policy to mitigate risks.