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AUSCERT External Security Bulletin Redistribution
ESB-2015.2343
Cisco ASR 1000 Series Aggregation Services Routers
Data-Plane Processing Denial of Service Vulnerability
8 September 2015
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AusCERT Security Bulletin Summary
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Product: Cisco ASR 1000 Series Routers
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Denial of Service -- Remote/Unauthenticated
Resolution: Mitigation
CVE Names: CVE-2015-6274
Original Bulletin:
http://tools.cisco.com/security/center/viewAlert.x?alertId=40708
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Vulnerability Alert Cisco ASR 1000 Series Aggregation Services Routers
Data-Plane Processing Denial of Service Vulnerability
Threat Type: CWE-119: Buffer Errors
IntelliShield ID: 40708
Version: 1
First Published: 2015 August 31 23:19 GMT
Last Published: 2015 August 31 23:19 GMT
Port: Not available
CVE: CVE-2015-6274
Urgency: Unlikely Use
Credibility: Confirmed C
Severity: Mild Damage
CVSS Base: 5.0
CVSS Version 2.0
CVSS Temporal: 4.8
Version Summary: Cisco ASR 1000 Series Aggregation Services Routers contain a
vulnerability that could allow an unauthenticated, remote attacker to cause a
denial of service condition.
Description
A vulnerability in the Cisco ASR 1000 Series Aggregation Services Routers
could allow an unauthenticated, remote attacker to cause a denial of service
(DoS) condition.
The vulnerability is due to the processing of excessive number of IPv4 packets
that require fragmentation and reassembly. An attacker could exploit ths
vulnerability by sending an excessive number of fragmented packets, causing
high Cisco QuantumFlow Processor (QFP) CPU utilization in the Embedded
Services Processor (ESP).
Cisco has confirmed the vulnerability; however, software updates are not
available.
Warning Indicators
At the time this alert was first published, Cisco ASR 1000 Series Aggregation
Services Routers version 15.5(3)S was vulnerable. Other releases may also be
affected.
IntelliShield Analysis
To exploit this vulnerability, the attacker must send an excessive number of
fragmented packets to the targeted system, making exploitation more difficult
in environments that restrict access from untrusted sources
Cisco indicates through the CVSS score that functional exploit code exists;
however, the code is not known to be publicly available.
Vendor Announcements
Cisco has released bug ID CSCuv71273 for registered users, which contains
additional details and an up-to-date list of affected product versions.
Impact
An unauthenticated, remote attacker could exploit the vulnerabilities to cause
high CPU utilization in the ESP by processing excessive IP packets on an
affected device, which could cause a DoS condition.
Technical Information
The vulnerability is due to the processing of an excessive number of IPv4
packets that require fragmentation and reassembly.
An unauthenticated, remote attacker could exploit the vulnerability by sending
100,000 packets per second or higher fragmented packets to the ASR 1000 Series
router, causing high QFP CPU utilization in the ESP.
Safeguards
Administrators are advised to allow only trusted users to have network access.
Administrators can help protect affected systems from external attacks by
using a solid firewall strategy.
Administrators may consider using IP-based access control lists (ACLs) to
allow only trusted systems to access the affected systems.
Administrators are advised to monitor affected systems.
Patches/Software
Updates are not available.
Alert History
Initial Release
Product Sets
The security vulnerability applies to the following combinations of products.
Primary Products:
Cisco Cisco ASR 1000 Series 15.5 Base, (3)S
Associated Products:
N/A
LEGAL DISCLAIMER
The urgency and severity ratings of this alert are not tailored to individual
users; users may value alerts differently based upon their network
configurations and circumstances. THE ALERT, AND INFORMATION CONTAINED
THEREIN, ARE PROVIDED ON AN "AS IS" BASIS AND DO NOT IMPLY ANY KIND OF
GUARANTEE OR WARRANTY, INCLUDING THE WARRANTIES OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR USE. YOUR USE OF THE ALERT, AND INFORMATION CONTAINED
THEREIN, OR MATERIALS LINKED FROM THE ALERT, IS AT YOUR OWN RISK. INFORMATION
IN THIS ALERT AND ANY RELATED COMMUNICATIONS IS BASED ON OUR KNOWLEDGE AT THE
TIME OF PUBLICATION AND IS SUBJECT TO CHANGE WITHOUT NOTICE. CISCO RESERVES
THE RIGHT TO CHANGE OR UPDATE ALERTS AT ANY TIME.
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