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AUSCERT External Security Bulletin Redistribution
ESB-2015.1652
Cisco IOS Software UBR Devices IPv6 VPN Multiprotocol Label
Switching Denial of Service Vulnerability
25 June 2015
===========================================================================
AusCERT Security Bulletin Summary
---------------------------------
Product: Cisco IOS Software
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Denial of Service -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2015-4203 CVE-2015-4200
Original Bulletin:
http://tools.cisco.com/security/center/viewAlert.x?alertId=39424
http://tools.cisco.com/security/center/viewAlert.x?alertId=39439
Comment: This bulletin contains two (2) Cisco Systems security advisories.
- --------------------------BEGIN INCLUDED TEXT--------------------
Vulnerability Alert
Cisco IOS Software UBR Devices IPv6 to IPv4 Subsystem Denial of Service
Vulnerability
Threat Type: CWE-399: Resource Management Errors
IntelliShield ID: 39424
Version: 1
First Published: 2015 June 22 14:53 GMT
Last Published: 2015 June 22 14:53 GMT
Port: Not available
CVE: CVE-2015-4200
Urgency: Unlikely Use
Credibility: Confirmed
Severity: Mild Damage
CVSS Base: 5.0
CVSS Version 2.0
CVSS Temporal: 4.1
Version Summary: Cisco Universal Broadband Routers running Cisco IOS Software
contain a vulnerability that could allow an unauthenticated, remote attacker
to cause a denial of service condition. Updates are available.
Description
A vulnerability in the IPv6 to IPv4 subsystem of Cisco IOS Software could
allow an unauthenticated, remote attacker to cause a standby Performance
Routing Engine (PRE) to leak a small portion of memory on a targeted system,
resulting in a denial of service (DoS) condition.
The vulnerability is due to a failure to free a portion of memory allocated to
store the IPv6 address of a connecting customer premises equipment (CPE)
device when a specific error condition is encountered. An attacker who can
trigger a specific type of failed CPE negotiation could cause the standby PRE
to leak a small portion of memory, resulting in a DoS condition.
Cisco has confirmed the vulnerability and released software updates.
Warning Indicators
Cisco Universal Broadband Router (UBR) devices running Cisco IOS Software are
affected.
IntelliShield Analysis
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 CSCug00885 for registered users, which contains
additional details and an up-to-date list of affected product versions.
Impact
An unauthenticated, remote attacker could exploit this vulnerability to cause
a standby PRE module to leak a small portion of memory, resulting in a DoS
condition.
Technical Information
The vulnerability is due to a failure to free a portion of memory allocated to
store the IPv6 address of a connecting CPE device when a specific error
condition is encountered.
An attacker who can trigger a specific type of failed CPE negotiation could
cause the standby PRE module to leak a small portion of memory, resulting in a
DoS condition.
Safeguards
Administrators are advised to apply the appropriate updates.
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
Cisco customers with active contracts can obtain updates through the Software
Center at the following link: Cisco. Cisco customers without contracts can
obtain upgrades by contacting the Cisco Technical Assistance Center at
1-800-553-2447 or 1-408-526-7209 or via email at tac@cisco.com.
Alert History
Initial Release
Product Sets
The security vulnerability applies to the following combinations of products.
Primary Products:
Cisco IOS 15.3S 15.3(3)S
Associated Products:
N/A
Alerts and bulletins on the Cisco Security Intelligence Operations Portal are
highlighted by analysts in the Cisco Threat Operations Center and represent a
subset of the comprehensive content that is available through Cisco Security
IntelliShield Alert Manager Service. This customizable threat and
vulnerability alert service provides security staff with access to timely,
accurate, and credible information about threats and vulnerabilities that may
affect their environment.
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.
- ----------------------------------------------------------------------------
Vulnerability Alert
Cisco IOS Software UBR Devices IPv6 VPN Multiprotocol Label Switching Denial
of Service Vulnerability
Threat Type: CWE-362: Race Conditions
IntelliShield ID: 39439
Version: 1
First Published: 2015 June 22 16:05 GMT
Last Published: 2015 June 22 16:05 GMT
Port: Not available
CVE: CVE-2015-4203
Urgency: Unlikely Use
Credibility: Confirmed
Severity: Mild Damage
CVSS Base: 5.4
CVSS Version 2.0
CVSS Temporal: 4.5
Version Summary: Cisco Universal Broadband Routers running Cisco IOS Software
contain a vulnerability that could allow an unauthenticated, remote attacker
to cause a denial of service condition. Updates are available.
Description
A vulnerability in Cisco Universal Broadband Routers performing IPv6 VPN over
Multiprotocol Label Switching (MPLS; 6VPE) and configured for NetFlow could
allow an unauthenticated, remote attacker to cause a crash of the Parallel
Express Forwarding (PXF) process on the Performance Routing Engine (PRE)
module.
The vulnerability is due to a race condition that may cause an incorrect
pointer to be used during IPv6 deaggregation. An attacker would need to
control a trusted MPLS neighbor that can forward a malformed 6VPE packet at a
high rate to an affected device. Successful exploitation could cause the PXF
process on the PXE module of a targeted device to crash, resulting in a denial
of service (DoS) condition
Cisco has confirmed the vulnerability and released software updates.
Warning Indicators
Cisco uBR10000 Series Universal Broadband Routers running Cisco IOS Software
are affected.
IntelliShield Analysis
To exploit this vulnerability, the attacker must take control of a trusted
MPLS neighbor that can forward a malformed 6VPE packet at a high rate to the
targeted device, making exploitation more difficult in environments that
restrict network 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 CSCud83396 for registered users, which contains
additional details and an up-to-date list of affected product versions.
Impact
An unauthenticated, remote attacker could exploit this vulnerability to cause
the PXF process on the PRE module on an affected device to crash, resulting in
a DoS condition.
Technical Information
The vulnerability is due to a race condition that could occur on an affected
device that may result in use of an incorrect pointer during IPv6
deaggregation.
An attacker who can take control of a trusted MPLS neighbor that can forward a
malformed 6VPE packet at a high rate to an affected device could exploit this
vulnerability to cause the PXF process on the PXE module of a targeted device
to crash, resulting in a DoS condition.
Safeguards
Administrators are advised to apply the appropriate updates.
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
Cisco customers with active contracts can obtain updates through the Software
Center at the following link: Cisco. Cisco customers without contracts can
obtain upgrades by contacting the Cisco Technical Assistance Center at
1-800-553-2447 or 1-408-526-7209 or via email at tac@cisco.com.
Alert History
Initial Release
Product Sets
The security vulnerability applies to the following combinations of products.
Primary Products:
Cisco IOS 12.2SCH 12.2(33)SCH
Associated Products:
N/A
Alerts and bulletins on the Cisco Security Intelligence Operations Portal are
highlighted by analysts in the Cisco Threat Operations Center and represent a
subset of the comprehensive content that is available through Cisco Security
IntelliShield Alert Manager Service. This customizable threat and
vulnerability alert service provides security staff with access to timely,
accurate, and credible information about threats and vulnerabilities that may
affect their environment.
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.
- --------------------------END INCLUDED TEXT--------------------
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