Cisco IOS Software contains a vulnerability that could allow an unauthenticated, remote attacker to cause a denial of service condition on a targeted device. 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 insufficient validation of Internet Key Exchange (IKE) packets by the affected software. An unauthenticated, remote attacker could exploit this vulnerability by sending specific IKE packets to a device configured with features that leverage IKEv1. A successful exploit could allow the attacker to cause a memory leak. A sustained attack could cause the device to reload or become unresponsive, resulting in a DoS condition for legitimate users.
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.
If the network is experiencing active exploitation, the Crypto IKE Dis count will increase. To identify if a device is being exploited by this vulnerability, examine the contents of the old buffers. A device that is affected by this vulnerability will show a buffer leak in the Crypto IKE Dis user and will show buffers being leaked in Crypto IK.
This vulnerability can be exploited via either IPv4 or IPv6. Only traffic destined to the device can trigger the vulnerability; transit traffic is not an exploit vector.
An attacker must be able to send malicious packets to the targeted device to exploit the vulnerability and may require access to trusted, internal networks. This access requirement may reduce the likelihood of a successful attack.
Cisco indicates through the CVSS score that proof-of-concept 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 on a targeted device. A sustained attack could cause the device to reload or become unresponsive, resulting in a DoS condition for legitimate users.
The vulnerability is due to insufficient validation of IKE packets by the affected software.
An unauthenticated, remote attacker could exploit this vulnerability by sending specific IKE packets to a device configured with features that leverage IKEv1. When the malicious packets are processed by the affected software, improper memory operations could result in a memory leak. A successful exploit could allow the attacker to use the memory leak to cause the device to reload or become unresponsive, resulting in a DoS condition for legitimate users.
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 may consider implementing a Cisco IOS Embedded Event Manager (EEM) policy that can be used on vulnerable Cisco IOS devices to identify and detect a memory leak that is caused by this vulnerability. The policy script is available at the following link: Cisco Beyond: Embedded Event Manager (EEM) Scripting Community
Apply hardware rate limiter features to limit packets that require processing by the device's CPU to mitigate DoS attacks.
Administrators are advised to monitor critical 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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