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Vulnerability Alert

Cisco IOS Software Queue Wedge Denial of Service Vulnerability

 
Threat Type:CWE-399: Resource Management Errors
IntelliShield ID:30700
Version:1
First Published:2013 September 25 16:33 GMT
Last Published:2013 September 25 16:33 GMT
Port: Not available
CVE:CVE-2013-5477
Urgency:Unlikely Use
Credibility:Confirmed
Severity:Mild Damage
CVSS Base:7.8 CVSS Calculator
CVSS Version 2.0
CVSS Temporal:6.4
Related Resources:
View related Security AdvisoryView related Event Response
 
 
Version Summary:Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition on a targeted device. Updates are available.
 
 
Description
A vulnerability in the T1/E1 driver queue implementation of Cisco IOS Software could allow an unauthenticated, remote attacker to cause an interface wedge condition, which could lead to loss of connectivity, loss of routing protocol adjacency, and could result in a denial of service (DoS) scenario.

The vulnerability is due to incorrect implementation of the T1/E1 driver queue. An attacker could exploit this vulnerability by sending bursty traffic through the affected interface driver. Repeated exploitation could cause a DoS condition.

Cisco has confirmed the vulnerability in a security advisory and has released software updates.
 
Warning Indicators
Cisco has published a list of affected Cisco IOS Software releases in the security advisory. The "Vendor Announcements" section of this alert contains a link to the advisory.
 
IntelliShield Analysis
To exploit this vulnerability, an attacker may require access to trusted, internal networks to send crafted requests to the affected software. This access requirement could limit the likelihood of a successful exploit.

Valid network traffic could trigger this vulnerability on affected devices. Recovery from this interface queue wedge requires a reload of the device.

A device is vulnerable if it is configured with T1/E1 signaling on an interface that is using an HDLC32 driver.

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 advisory for bug ID CSCub67465 at the following link: cisco-sa-20130925-wedge
 
Impact
An unauthenticated, remote attacker could exploit this vulnerability to cause a DoS condition on a targeted device.
 
Technical Information
The vulnerability is due to incorrect implementation of the T1/E1 driver queue.

An unauthenticated, remote attacker with some knowledge of the affected infrastructure could exploit this vulnerability by sending a bursty profile of network packets through a targeted device. When the bursty traffic is processed by the affected software, packets queued by a Cisco IOS router or switch are never removed from the queue, leading to an interface queue wedge. A successful exploit could allow the attacker to interrupt traffic processing on the egress interface of the device. Repeated exploitation could cause a sustained DoS condition.
 
Safeguards
Administrators are advised to apply the appropriate updates.

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

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

For more information about queue wedges and a few detection mechanisms that may be used to identify a blocked interface on Cisco IOS Software (including a white paper describing how this condition can be detected using SNMP) see Cisco IOS Queue Wedges Explained

Prevent disruption of communication between devices by reducing the impact of attacks which may directly impact the CPU performance of the individual devices. For control plane hardening best practices, consult the Cisco Guide to Harden Cisco IOS Devices.

Apply hardware rate limiter features to limit packets requiring processing by the device's CPU to mitigate DoS attacks. See the vendor's documentation for specific configuration instructions. For hardware rate limiting configuration details, see Cisco Catalyst 6500 Denial of Service (DoS) Protection Configuration Guide.

Understanding activity on the network provides information and visibility that can be used to identify potential security incidents. Organizations should log events from devices and review the logged data to provide insight into anomalies or malicious activity. For logging best practices, see Cisco Guide to Harden Cisco IOS Devices.

Administrators may consider analyzing network traffic to identify bursty traffic, see Wireshark Use to Identify Bursty Traffic on Catalyst Switches.

Administrators are advised to monitor network traffic for security-related network activity. Cisco NetFlow can identify such activity. For more information about Cisco NetFlow, see Introduction to Cisco IOS NetFlow - A Technical Overview.

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:
CiscoIOS 15.0M 15.0(1)M, 15.0(1)M1, 15.0(1)M10, 15.0(1)M2, 15.0(1)M3, 15.0(1)M4, 15.0(1)M5, 15.0(1)M6, 15.0(1)M6a, 15.0(1)M7, 15.0(1)M8, 15.0(1)M9 | 15.0XA 15.0(1)XA, 15.0(1)XA1, 15.0(1)XA2, 15.0(1)XA3, 15.0(1)XA4, 15.0(1)XA5 | 15.1GC 15.1(2)GC, 15.1(2)GC1, 15.1(2)GC2, 15.1(4)GC, 15.1(4)GC1 | 15.1M 15.1(4)M, 15.1(4)M0a, 15.1(4)M0b, 15.1(4)M1, 15.1(4)M2, 15.1(4)M3, 15.1(4)M3a, 15.1(4)M4, 15.1(4)M5, 15.1(4)M6 | 15.1T 15.1(1)T, 15.1(1)T1, 15.1(1)T2, 15.1(1)T3, 15.1(1)T4, 15.1(1)T5, 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 | 15.1XB 15.1(1)XB, 15.1(1)XB1, 15.1(1)XB2, 15.1(1)XB3, 15.1(4)XB4, 15.1(4)XB5, 15.1(4)XB5a, 15.1(4)XB6, 15.1(4)XB7, 15.1(4)XB8a | 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 | 15.2JA 15.2(2)JA, 15.2(2)JA1, 15.2(4)JA | 15.2JAX 15.2(2)JAX | 15.2JB 15.2(2)JB, 15.2(2)JB1 | 15.2M 15.2(4)M, 15.2(4)M1, 15.2(4)M2 | 15.2T 15.2(1)T, 15.2(1)T1, 15.2(1)T2, 15.2(1)T3, 15.2(1)T3a, 15.2(1)T4, 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, 15.2(100)T | 15.2XA 15.2(3)XA | 15.2XB 15.2(4)XB10 | 15.3T 15.3(1)T, 15.3(1)T1

Associated Products:
N/A




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