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AUSCERT External Security Bulletin Redistribution
ESB-2020.0609
Cisco Email Security Appliance Shortened URL Denial of
Service Vulnerability
21 February 2020
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AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco Email Security Appliance
Publisher: Cisco Systems
Operating System: Network Appliance
Impact/Access: Denial of Service -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2020-3132
Original Bulletin:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-esa-shrt-dos-wM54R8qA
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Cisco Email Security Appliance Shortened URL Denial of Service Vulnerability
Priority: Medium
Advisory ID: cisco-sa-esa-shrt-dos-wM54R8qA
First Published: 2020 February 19 16:00 GMT
Version 1.0: Final
Workarounds: YesCisco Bug IDs: CSCvp75565
CVE-2020-3132
CWE-400
CVSS Score:
6.8 AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
Summary
o A vulnerability in the email message scanning feature of Cisco AsyncOS
Software for Cisco Email Security Appliance (ESA) could allow an
unauthenticated, remote attacker to cause a temporary denial of service
(DoS) condition on an affected device.
The vulnerability is due to inadequate parsing mechanisms for specific
email body components. An attacker could exploit this vulnerability by
sending a malicious email containing a high number of shortened URLs
through an affected device. A successful exploit could allow the attacker
to consume processing resources, causing a DoS condition on an affected
device. To successfully exploit this vulnerability, certain conditions
beyond the control of the attacker must occur.
Cisco has released software updates that address the vulnerability
described in this advisory. There is a workaround that addresses this
vulnerability.
This advisory is available at the following link:
https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-esa-shrt-dos-wM54R8qA
Affected Products
o Vulnerable Products
At the time of publication, this vulnerability affected Cisco ESA and Cisco
Cloud Email Security (CES) s oftware releases earlier than 12.5.1-037 and
earlier than 13.0.0-375.
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability.
Workarounds
o Administrators can disable email URL filtering for shortened URLs by
connecting to a device through the CLI and typing the command
websecurityadvancedconfig . Under Do you want to enable URL filtering for
shortened URLs type N and commit the changes. URL filtering for shortened
URLs is enabled by default.
Fixed Software
o Cisco has released software updates that address the vulnerability
described in this advisory. Customers may only install and expect support
for software versions and feature sets for which they have purchased a
license. By installing, downloading, accessing, or otherwise using such
software upgrades, customers agree to follow the terms of the Cisco
software license: https://www.cisco.com/c/en/us/products/
end-user-license-agreement.html
Fixed Releases
At the time of publication, Cisco ESA and Cisco CES software releases
12.5.1-037 and later and 13.0.0-375 and later contained the fix for this
vulnerability.
Cisco Cloud Email Security (CES) includes the Cisco ESA and Cisco Content
Security Management Appliance (SMA) as part of the service solution. Cisco
provides regular maintenance of the products included in this solution.
Customers can also request a software upgrade by contacting Cisco CES
support.
Exploitation and Public Announcements
o 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
o This vulnerability was found during the resolution of a Cisco TAC support
case.
Cisco Security Vulnerability Policy
o 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.
URL
o https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/
cisco-sa-esa-shrt-dos-wM54R8qA
Revision History
o +----------+---------------------------+----------+--------+--------------+
| Version | Description | Section | Status | Date |
+----------+---------------------------+----------+--------+--------------+
| 1.0 | Initial public release. | - | Final | 2020-FEB-19 |
+----------+---------------------------+----------+--------+--------------+
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