Cisco Security Advisory
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CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
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Multiple Cisco products are affected by a vulnerability in the Ethernet Frame Decoder of the Snort detection engine that could allow an unauthenticated, adjacent attacker to cause a denial of service (DoS) condition.
The vulnerability is due to improper handling of error conditions when processing Ethernet frames. An attacker could exploit this vulnerability by sending malicious Ethernet frames through an affected device. A successful exploit could allow the attacker to exhaust disk space on the affected device, which could result in administrators being unable to log in to the device or the device being unable to boot up correctly.
Note: Manual intervention is required to recover from this situation. Customers are advised to contact the Cisco Technical Assistance Center (TAC) to help recover a device in this condition.
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-snort-ethernet-dos-HGXgJH8n
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Vulnerable Products
This vulnerability affects all open source Snort project releases earlier than Release 2.9.17. For more information on open source Snort, see the Snort website.
Impact to Cisco Products
This vulnerability affects the following Cisco products, if they are running a vulnerable release of Cisco UTD Snort IPS Engine Software for IOS XE or Cisco UTD Engine for IOS XE SD-WAN Software and are configured to pass Ethernet frames to the Snort detection engine:
- 1000 Series Integrated Services Routers (ISRs)
- 4000 Series Integrated Services Routers (ISRs)
- Catalyst 8000V Edge Software
- Catalyst 8200 Series Edge Platforms
- Catalyst 8300 Series Edge Platforms
- Cloud Services Router 1000V Series
- Integrated Services Virtual Router (ISRv)
For information about which Cisco software releases are vulnerable, see the Fixed Software section of this advisory.
Products Confirmed Not Vulnerable
Cisco has confirmed that this vulnerability does not affect the following Cisco products:
- 3000 Series Industrial Security Appliances (ISAs)
- Adaptive Security Appliance (ASA) Software
- Catalyst 8500 Series Edge Platforms
- Catalyst 8500L Series Edge Platforms
- Firepower Management Center (FMC) Software
- Firepower Threat Defense (FTD) Software1
- Meraki Security Appliances
1. A related vulnerability affecting Cisco FTD Software was previously resolved and disclosed as Cisco Firepower Threat Defense Software Inline Pair/Passive Mode Denial of Service Vulnerability.
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There are no workarounds that address this vulnerability.
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Cisco has released free 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.htmlAdditionally, customers may only download software for which they have a valid license, procured from Cisco directly, or through a Cisco authorized reseller or partner. In most cases this will be a maintenance upgrade to software that was previously purchased. Free security software updates do not entitle customers to a new software license, additional software feature sets, or major revision upgrades.
When considering software upgrades, customers are advised to regularly consult the advisories for Cisco products, which are available from the Cisco Security Advisories 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.
Customers Without Service Contracts
Customers who purchase directly from Cisco but do not hold a Cisco service contract and customers who make purchases through third-party vendors but are unsuccessful in obtaining fixed software through their point of sale should obtain upgrades by contacting the Cisco TAC: https://www.cisco.com/c/en/us/support/web/tsd-cisco-worldwide-contacts.html
Customers should have the product serial number available and be prepared to provide the URL of this advisory as evidence of entitlement to a free upgrade.
Fixed Releases
Customers are advised to upgrade to an appropriate fixed software release as indicated in the following table(s):
Cisco IOS XE Software and Cisco IOS XE SD-WAN Software
Cisco UTD Snort IPS Engine Software for IOS XE and
Cisco UTD Engine for IOS XE SD-WAN Software1First Fixed Release for This Vulnerability Earlier than 16.12 Migrate to a fixed release. 16.12 16.12.5 17.1 Migrate to a fixed release. 17.2 Migrate to a fixed release. 17.3 17.3.3 17.4 17.4.1a 1. Starting with release 17.2.1, Cisco IOS XE Software and Cisco IOS XE SD-WAN Software share the same image file.Open Source Snort
The open source Snort project versions 2.9.17 and later contain the fix for this vulnerability. For more information on open source Snort, see the Snort website.
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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.
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This vulnerability was found during the resolution of a Cisco TAC support case.
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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.
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Show LessVersion Description Section Status Date 1.0 Initial public release. — Final 2021-MAR-03
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