Vulnerability Alert

Cisco IOS Software Tunneled Traffic Queue Wedge Denial of Service Vulnerability

 
Threat Type:CWE-399: Resource Management Errors
IntelliShield ID:26898
Version:1
First Published:2012 September 26 16:26 GMT
Last Published:2012 September 26 16:26 GMT
Port: Not available
CVE:CVE-2012-4620
Urgency:Unlikely Use
Credibility:Confirmed
Severity:Mild Damage
CVSS Base:7.8 CVSS Calculator
CVSS Version 2.0
CVSS Temporal:6.4
 
Version Summary:Cisco IOS software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are available.
 
 
Description
Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on a targeted device.

The vulnerability is due to improper handling of IP tunneled ingress traffic by the Cisco IOS Software. An unauthenticated, remote attacker could exploit this vulnerability by sending Generic Routing Encapsulation IP (GRE/IP), IP in IP (IPIP), or IPv4 encapsulated IPv6 packets, which terminate at the device, to a device with a vulnerable tunnel configuration. Successful exploitation could allow the attacker to cause the affected device to stop responding to legitimate IP tunnel traffic on an affected interface, resulting in a DoS condition.

Cisco has confirmed this vulnerability and released software updates.
 
Warning Indicators
Cisco has published a list of affected Cisco IOS Software releases in a security advisory. The Vendor Announcements section of this alert contains a link to the security advisory.
 
IntelliShield Analysis
Only Cisco IOS Software running on the Cisco 10000 series router has been demonstrated to be affected.

Cisco indicates through the CVSS score that functional exploit code exists; however, the code is not known to be publicly available.

To exploit this vulnerability, the attacker may need access to trusted, internal network resources. This access requirement reduces the likelihood of a successful exploit.
 
Vendor Announcements
Cisco has released a security advisory for Cisco bug ID CSCts66808 at the following link: cisco-sa-20120926-c10k-tunnels
 
Impact
An unauthenticated, remote attacker could exploit this vulnerability to cause the affected device to stop responding to legitimate IP tunnel traffic on an affected interface, resulting in a DoS condition for legitimate users.
 
Technical Information
The vulnerability exists because the Cisco IOS Software fails to properly decrement the input queue of an IP tunnel interface configured with tunnel mode gre ip (GRE/IP), tunnel mode ipip (IPIP), or tunnel mode ipv6ip (IPv6inIP) when processing packets from IPv4 protocol types 41, 47, or 94.

An unauthenticated, remote attacker could exploit this vulnerability by sending GRE/IP, IPIP, or IPv4 encapsulated IPv6 packets, which terminate at the device, to a device with a vulnerable tunnel configuration. When the malicious packets are processed by the Cisco IOS Software, an error condition could allow the attacker to cause the affected device to stop processing legitimate IP tunnel traffic on an affected interface, resulting in a DoS condition for legitimate IP tunnel traffic.
 
Safeguards
Administrators are advised to apply the appropriate updates.

Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected devices.

Administrators are advised to allow only trusted users to have network access.

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 e-mail at tac@cisco.com.
 
Alert History
 
Initial Release


Product Sets
 
The security vulnerability applies to the following combinations of products.

Primary Products:
CiscoIOS 12.2SB 12.2(33)SB, 12.2(33)SB1, 12.2(33)SB1a, 12.2(33)SB1b, 12.2(33)SB10, 12.2(33)SB11, 12.2(33)SB2, 12.2(33)SB3, 12.2(33)SB4, 12.2(33)SB5, 12.2(33)SB6, 12.2(33)SB6a, 12.2(33)SB6aa, 12.2(33)SB6b, 12.2(33)SB7, 12.2(33)SB8, 12.2(33)SB8b, 12.2(33)SB8c, 12.2(33)SB8d, 12.2(33)SB8e, 12.2(33)SB8f, 12.2(33)SB8g, 12.2(33)SB9, 12.2(34)SB1, 12.2(34)SB2, 12.2(34)SB3, 12.2(34)SB4, 12.2(34)SB4a, 12.2(34)SB4b, 12.2(34)SB4c, 12.2(34)SB4d | 12.2SRC 12.2(33)SRC, 12.2(33)SRC1 | 12.2SRD 12.2(33)SRD | 15.0S 15.0(1)S, 15.0(1)S1, 15.0(1)S2, 15.0(1)S3a, 15.0(1)S4, 15.0(1)S4a

Associated Products:
N/A




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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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