Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition. Updates are available.
Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.
The vulnerability is due to an unspecified vulnerability when the device is handling crafted encryption packets. An unauthenticated, remote attacker could exploit this vulnerability by sending a crafted encryption packet to the affected device. An exploit could cause the device to reload, resulting in a DoS condition.
Cisco has confirmed this vulnerability and released updated software.
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.
Only systems configured with one or more of the following features are affected by this vulnerability: SSL VPN, SSH, or Internet Key Exchange (IKE) encrypted nonces. Additional information about determining if a device is vulnerable is available in the vendor advisory.
Exploitation of this vulnerability requires a three-way TCP handshake for the TCP ports. For this reason, attackers will not be able to spoof the source address of the malicious packets, making it harder for the attacker to conceal the source of their attacks. However, for the IKE encrypted nonces service which uses UDP, source address spoofing will be possible.
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 a DoS condition on the affected device. Repeated exploitation could result in a persistent DoS condition.
The vulnerability is due to an unspecified error that could occur when the vulnerable device handles encryption packets for SSL VPN, SSH, or IKE security nonces. An unauthenticated, remote attacker could send a malicious encrypted packet to any of the following ports depending on which services have been enabled on the device:
When the affected device attempts to process the malicious packet, it could cause the device to reload, resulting in a DoS condition.
Administrators are advised to apply the appropriate updates.
Administrators may consider disabling all of the affected features.
Administrators may mitigate this vulnerability for SSH by using access control lists (ACLs) in local firewalls to restrict access to TCP port 22 to trusted IP addresses.
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 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.