Cisco Firewall Services Module and Cisco ASA 5500 Series Adaptive Security Appliance contain multiple vulnerabilities that could allow an unauthenticated, remote attacker to cause a denial of service condition on a targeted system. Updates are available.
Description
Cisco Firewall Services Module (FWSM) and Cisco ASA 5500 Series Adaptive Security Appliance (ASA) contain multiple vulnerabilities that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on a targeted system.
These vulnerabilities are due to insufficient validation of user-supplied input processed by the affected software. An unauthenticated, remote attacker could exploit these vulnerabilities by sending crafted Distributed Computing Environment/Remote Procedure Call (DCERPC) packets to a vulnerable system. Processing these packets could cause a targeted device to reload, resulting in a DoS condition on the system.
Cisco has confirmed these vulnerabilities and released updated software.
Warning Indicators
The following releases of Cisco FWSM are vulnerable while running on Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers with the DCERPC inspection engine enabled:
Cisco FWSM Releases prior to 3.2(24)
Cisco FWSM Releases 4.0.17 and prior
Cisco FWSM Releases prior to 4.1(7)
The following releases of Cisco ASA Software are also affected by these vulnerabilities:
Cisco ASA Releases prior to 8.3(2.25)
Cisco ASA Releases prior to 8.4(2.4)
Cisco ASA Releases prior to 8.5(1.12)
IntelliShield Analysis
To exploit these vulnerabilities, an attacker would need access to an internal network to send crafted packets to a vulnerable device. In a typical network configuration, such devices are placed on trusted, internal networks. This access requirement could limit the possibility 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.
An unauthenticated, remote attacker could exploit these vulnerabilities to cause an affected device to reload, resulting in a DoS condition.
Technical Information
The vulnerabilities are due to insufficient validation of user-supplied input processed by the affected software. The DCERPC inspection engine of an affected device fails to validate DCERPC packets in a valid DCERPC session. These vulnerabilities can be triggered by IP version 4 and IP version 6 traffic. In addition, these vulnerabilities also affect both routed and transparent firewall modes in both single-context and multicontext modes.
An unauthenticated, remote attacker could exploit these vulnerabilities by sending crafted DCERPC packets to a vulnerable system for inspection. Processing these packets could cause a device to reload or possibly overflow the stack, which may allow the attacker to execute arbitrary commands.
Safeguards
Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
Administrators may consider disabling the DCERPC inspection engine if this option is not required.
Administrators are advised to implement an intrusion prevention system (IPS) or intrusion detection system (IDS) to help detect and prevent attacks that attempt to exploit these vulnerabilities.
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.
Signatures
Cisco Systems Cisco Intrusion Prevention System (IPS) 6.0
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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.
