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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 =========================================================================== AUSCERT External Security Bulletin Redistribution ESB-2017.2249 Cisco IOS and Cisco IOS XE Software UDP Packet Processing Denial of Service Vulnerability 7 September 2017 =========================================================================== AusCERT Security Bulletin Summary --------------------------------- Product: Cisco IOS and Cisco IOS XE Publisher: Cisco Systems Operating System: Cisco Impact/Access: Denial of Service -- Remote/Unauthenticated Resolution: Patch/Upgrade CVE Names: CVE-2017-6627 Original Bulletin: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170906-ios-udp - --------------------------BEGIN INCLUDED TEXT-------------------- Cisco IOS and Cisco IOS XE Software UDP Packet Processing Denial of Service Vulnerability Medium Advisory ID: cisco-sa-20170906-ios-udp First Published: 2017 September 6 16:00 GMT Version 1.0: Final Workarounds: Yes Cisco Bug IDs: CSCup10024 CSCva55744 CSCva95506 CVSS Score: Base 5.3 Base 5.3 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L/E:X/RL:X/RC:X CVE-2017-6627 CWE-399 Summary A vulnerability in the UDP processing code of Cisco IOS and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause the input queue of an affected system to hold UDP packets, causing an interface queue wedge and a denial of service (DoS) condition. The vulnerability is due to Cisco IOS Software application changes that create UDP sockets and leave the sockets idle without closing them. An attacker could exploit this vulnerability by sending UDP packets with a destination port of 0 to an affected device. A successful exploit could allow the attacker to cause UDP packets to be held in the input interfaces queue, resulting in a DoS condition. The input interface queue will stop holding UDP packets when it receives 250 packets. There are workarounds that address this vulnerability. This advisory is available at the following link: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170906-ios-udp Affected Products Vulnerable Products This vulnerability affects Cisco IOS and Cisco IOS XE Software. 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 vulnerability. Workarounds To work around this vulnerability, administrators can set a maximum hold queue value that is greater than 250 for all device interfaces. The following example shows how to set the value to 350 by using the hold queue in interface configuration command: Router# configure terminal Router(config)# interface gigabitEthernet 1 Router(config-if)# hold-queue 350 in Administrators can also configure an access-control list (ACL) that blocks UDP packets with a destination port of 0 and apply the ACL to all device interfaces, for example: Extended IP access list 180 10 deny udp any any eq 0 Fixed Software 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 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. 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. URL https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170906-ios-udp Revision History Version Description Section Status Date 1.0 Initial public release. - Final 2017-September-06 LEGAL DISCLAIMER 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. - --------------------------END INCLUDED TEXT-------------------- You have received this e-mail bulletin as a result of your organisation's registration with AusCERT. The mailing list you are subscribed to is maintained within your organisation, so if you do not wish to continue receiving these bulletins you should contact your local IT manager. If you do not know who that is, please send an email to auscert@auscert.org.au and we will forward your request to the appropriate person. NOTE: Third Party Rights This security bulletin is provided as a service to AusCERT's members. As AusCERT did not write the document quoted above, AusCERT has had no control over its content. The decision to follow or act on information or advice contained in this security bulletin is the responsibility of each user or organisation, and should be considered in accordance with your organisation's site policies and procedures. 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