Vulnerability Alert

Cisco IOS Software SSL VPN Interface Queue Wedge Denial of Service Vulnerability

 
Threat Type:CWE-20: Input Validation
IntelliShield ID:31757
Version:1
First Published:2013 November 13 20:19 GMT
Last Published:2013 November 13 20:19 GMT
Port: Not available
CVE:CVE-2013-6686
BugTraq ID:63699
Urgency:Possible use
Credibility:Confirmed
Severity:Mild Damage
CVSS Base:6.8 CVSS Calculator
CVSS Version 2.0
CVSS Temporal:5.6
 
Version Summary:Cisco IOS Software contains a vulnerability that could allow an authenticated, remote attacker to create a denial of service condition. Updates are available.
 
 
Description
A vulnerability in the Datagram Transport Layer Security (DTLS) function of the Cisco IOS Software SSL VPN feature could allow an authenticated, remote attacker to cause the SSL VPN gateway interface to stop processing traffic when the queue is full, resulting in a denial of service (DoS) condition.

The vulnerability is due to improper processing of specific DTLS packets. An attacker could exploit this vulnerability by creating an SSL session and then sending crafted DTLS packets. An exploit could allow the attacker to cause the SSL VPN gateway interface to become full, resulting in a DoS condition.

Cisco has confirmed the vulnerability in a security notice and released software updates.
 
Warning Indicators
At the time this alert was first published, Cisco IOS Software Releases 15.3(1)T2 and prior were vulnerable. Later releases of Cisco IOS Software may also be vulnerable.
 
IntelliShield Analysis
To exploit this vulnerability, an attacker would need to authenticate to the targeted device to send specific DTLS packets to the vulnerable system. This access requirement decreases the likelihood of a successful exploit.

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 a security notice at the following link: CVE-2013-6686

Customers are advised to consult Cisco bug IDs CSCuh97409 and CSCud90568 for a complete list of affected product versions.
 
Impact
An authenticated, remote attacker could exploit this vulnerability to cause the SSL VPN gateway interface on an affected device to stop processing traffic, resulting in a DoS condition.
 
Technical Information
The vulnerability is due to improper processing of specific DTLS packets by a device running an affected version of Cisco IOS Software.

An authenticated, remote attacker could exploit this vulnerability by creating an SSL session and then sending crafted DTLS packets. An exploit could allow the attacker to cause the SSL VPN gateway interface to become full, 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 are advised to allow only privileged users to access administration or management systems.

Administrators are advised to monitor affected systems.
 
Patches/Software
Cisco customers with active contracts should contact their Cisco support team for assistance in upgrading to a software version that includes fixes for this vulnerability. Cisco customers without contracts may contact the Cisco Technical Assistance Center at 1-800-553-2447 or 1-408-526-7209 or via email at tac@cisco.com for assistance.
 
Alert History
 
Initial Release


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

Primary Products:
CiscoIOS 15.1GC 15.1(2)GC, 15.1(2)GC1, 15.1(2)GC2 | 15.1T 15.1(2)T, 15.1(2)T0a, 15.1(2)T1, 15.1(2)T2, 15.1(2)T2a, 15.1(2)T3, 15.1(2)T4, 15.1(2)T5, 15.1(3)T, 15.1(3)T1, 15.1(3)T2, 15.1(3)T3, 15.1(3)T4, 15.1(4)T | 15.2GC 15.2(1)GC, 15.2(1)GC1, 15.2(1)GC2, 15.2(2)GC, 15.2(3)GC, 15.2(3)GC1 | 15.2GCA 15.2(3)GCA, 15.2(3)GCA1 | 15.2M 15.2(4)M, 15.2(4)M1, 15.2(4)M2, 15.2(4)M3 | 15.2T 15.2(1)T, 15.2(1)T1, 15.2(1)T2, 15.2(1)T3, 15.2(1)T3a, 15.2(2)T, 15.2(2)T1, 15.2(2)T2, 15.2(2)T3, 15.2(3)T, 15.2(3)T1, 15.2(3)T2, 15.2(3)T3 | 15.3T 15.3(1)T, 15.3(1)T1, 15.3(1)T2

Associated Products:
N/A




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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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