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Vulnerability Alert

Cisco Carrier Routing System Security Bypass Vulnerability

 
Threat Type:CWE-264: Permissions, Privileges, and Access Control
IntelliShield ID:26618
Version:1
First Published:2012 August 10 14:48 GMT
Last Published:2012 August 10 14:48 GMT
Port: Not available
CVE:CVE-2012-1342
BugTraq ID:54852
Urgency:Unlikely Use
Credibility:Confirmed
Severity:Mild Damage
CVSS Base:4.3 CVSS Calculator
CVSS Version 2.0
CVSS Temporal:3.6
 
Version Summary:Cisco Carrier Routing System contains a vulnerability that could allow an unauthenticated, remote attacker to bypass security protections and gain unauthorized access. Updates are available.
 
 
Description
Cisco Carrier Routing System contains a vulnerability that could allow an unauthenticated, remote attacker to bypass security protections and gain unauthorized network access.

The vulnerability is due to improper handling of IP version 4 (IPv4) fragments in the affected device. An unauthenticated, remote attacker could exploit this vulnerability by sending malicious requests to the device. When processed, the requests could bypass access control entries (ACEs), allowing the attacker to send network requests to restricted network segments.

Cisco has confirmed this vulnerability and released software updates.
 
Warning Indicators
Cisco Carrier Routing System with software version 3.9, 4.0, or 4.1 is vulnerable.
 
IntelliShield Analysis
The vulnerability affects only systems that use ACLs to restrict access to specific network segments or hosts and only for noninitial IPv4 fragments. This vulnerability does not apply to nonfragments or to the initial fragment.

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 issued a release note enclosure for Cisco bug ID CSCtj10975 at the following link: Cisco CRS-1 8-Slot Line Card Chassis
 
Impact
An unauthenticated, remote attacker could exploit the vulnerability to bypass ACEs and gain unauthorized network access.
 
Technical Information
The vulnerability occurs because the IPv4 protocol is ignored when matching noninitial fragments to an ACE. This vulnerability applies only when noninitial IPv4 fragments with any protocol match the ACE. Noninitial fragments are those with a fragment offset not equal to zero.

An unauthenticated, remote attacker could exploit this vulnerability by sending malicious requests to the system. The device may allow the attacker to bypass an ACE by using fragmented packets to gain unauthorized network access.
 
Safeguards
Administrators are advised to apply the appropriate updates.

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:
CiscoCisco Carrier Routing System (CRS) 3.9 Base | 4.0 Base | 4.1 Base

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.
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