Cisco IOS and IOS XE 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 Internet Key Exchange (IKE) protocol of Cisco IOS Software and Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition.
The vulnerability is due to improper handling of crafted IKE packets by the affected software. An attacker could exploit this vulnerability by sending crafted IKE packets to a device configured with features that leverage IKE version 1 (IKEv1). A successful exploit could cause Cisco IOS Software not to release allocated memory, causing a memory leak. A sustained attack may result in a device reload, resulting in a DoS condition for legitimate users.
Cisco has confirmed the vulnerability in a security advisory and released software updates.
Cisco devices that are running Cisco IOS Software or Cisco IOS-XE Software are vulnerable when they are configured to use IKEv1 or IKE version 2 (IKEv2).
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.
To exploit this vulnerability, the attacker would need the ability to send malformed IKEv1 packets to the targeted system. To achieve this objective, 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.
Although IKEv1 is automatically enabled on Cisco IOS Software and Cisco IOS XE Software when IKEv1 or IKEv2 is configured, the vulnerability can be triggered only by sending a malformed IKEv1 packet; however in specific conditions, normal IKEv1 packets can also cause an affected release of Cisco IOS Software to leak memory.
Only IKEv1 is affected by this vulnerability.
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 memory leak in the affected software, resulting in a DoS condition.
The vulnerability is due to incorrect handling of malformed IKE packets by the affected software.
An unauthenticated, remote attacker could exploit this vulnerability by sending malformed IKEv1 packets via UDP ports 500, 848, or 4500 to an affected device. Processing the malformed IKEv1 packets could trigger a memory leak on an affected device, 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 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.
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