Cisco Adaptive Security Appliance (ASA) Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are available.
A vulnerability in the DNS inspection engine code of Cisco ASA Software could allow an unauthenticated, remote attacker to trigger a reload of the affected device.
This vulnerability is due to improper processing of some fields in DNS messages. An attacker could exploit this vulnerability by sending a crafted DNS message that triggers inspection by an affected device.
Cisco has confirmed the vulnerability in a security advisory and released software updates.
Cisco ASA Software versions prior to 9.0(1.2) are affected.
To exploit this vulnerability, an attacker would need to send crafted DNS messages through the targeted 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 this vulnerability to cause the targeted device to reload, resulting in a denial of service (DoS) condition. Repeated exploitation could result in a sustained DoS condition.
The vulnerability is due to improper processing of certain DNS messages processed by the DNS inspection engine of the affected software.
An unauthenticated, remote attacker could exploit this vulnerability by sending a crafted DNS message through an affected device. Processing the crafted DNS message could trigger the affected device to reload, resulting in a DoS condition.
Administrators are advised to apply the appropriate updates.
Administrators are advised to allow only trusted users to have network access.
Administrators may consider disabling DNS inspection if this feature is not needed.
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 this vulnerability.
Administrators are advised to monitor affected systems.
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 firstname.lastname@example.org.
The security vulnerability applies to the following combinations of products.
Cisco Adaptive Security Appliance (ASA) Software
9.0 .1, .2
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