Vulnerability Alert

Cisco IOS Software Zone-Based Firewall and Content Filtering Vulnerability

 
Threat Type:CWE-20: Input Validation
IntelliShield ID:30699
Version:1
First Published:2013 September 25 16:22 GMT
Last Published:2013 September 25 16:22 GMT
Port: Not available
CVE:CVE-2013-5476
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
A vulnerability in the Zone-Based Firewall (ZFW) component of Cisco IOS Software could allow an unauthenticated, remote attacker to cause an affected device to hang or reload.

The vulnerability is due to improper processing of specific HTTP packets when the device is configured for content filtering or HTTP application layer gateway inspection. An attacker could exploit this vulnerability by sending specific HTTP packets through an affected device. An exploit could allow the attacker to cause an affected device to hang or reload.

Cisco confirmed the vulnerability in a security advisory and released software updates.
 
Warning Indicators
Cisco devices that are running affected Cisco IOS Software versions are vulnerable when HTTP application layer gateway (ALG) inspection or Cisco IOS Content filtering is configured under the ZBFW.

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, the attacker must send HTTP packets to the targeted system. To achieve this, the attacker may need access to trusted, internal network resources in which the targeted device may reside. This access requirement reduces the likelihood of a successful exploit.

Only transit traffic can trigger this vulnerability; HTTP traffic destined to a vulnerable device cannot trigger this vulnerability.

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 Cisco bug ID CSCtx56174 at the following link: cisco-sa-20130925-cce
 
Impact
An unauthenticated, remote attacker could exploit this vulnerability to cause an affected device to hang or reload, resulting in a denial of service (DoS) condition.
 
Technical Information
The vulnerability is due to improper processing of specific HTTP packets when an affected device is configured for content filtering or HTTP ALG inspection.

An unauthenticated, remote attacker could exploit this vulnerability by sending specific HTTP packets through an affected device. If successful, the attacker could cause an affected device to hang or reload, 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 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 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 15.1GC 15.1(4)GC, 15.1(4)GC1 | 15.1M 15.1(4)M2, 15.1(4)M3, 15.1(4)M3a, 15.1(4)M4, 15.1(4)M5 | 15.1XB 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 | 15.2T 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(2)T4, 15.2(3)T, 15.2(3)T1, 15.2(3)T2, 15.2(3)T3 | 15.2XA 15.2(3)XA

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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