K42378447 : IPsec IKEv1 vulnerability CVE-2018-5389

Security Advisory Description

The Internet Key Exchange v1 main mode is vulnerable to offline dictionary or brute force attacks. Reusing a key pair across different versions and modes of IKE could lead to cross-protocol authentication bypasses. It is well known, that the aggressive mode of IKEv1 PSK is vulnerable to offline dictionary or brute force attacks. For the main mode, however, only an online attack against PSK authentication was thought to be feasible. This vulnerability could allow an attacker to recover a weak Pre-Shared Key or enable the impersonation of a victim host or network. (CVE-2018-5389)

Impact

BIG-IP

There are four types of attacks on the IKEv1 protocol implementations affected by this vulnerability:

• Impersonating a device by performing a Bleichenbacher Oracle attack on its IKEv1 implementation of PKE (Public Key Encryption) based authentication.
• Impersonating a device by performing a Bleichenbacher Oracle attack on its IKEv1 implementation of RPKE (Revised Public Key Encryption) based authentication.
• Impersonating a device by forging its RSA signature through Bleichenbacher Oracle attack on its IKEv1 implementation of the PKE and RPKE-based authentication types.
• Performing an offline dictionary attack on a Pre-Shared Key (PSK) based authentication type for IKEv1.

The BIG-IP system is not affected by the three impersonating attack types.

The BIG-IP system that contains IKEv1 configuration using a weak (low-entropy) PSK is susceptible to the exploit of this vulnerability.

Enterprise Manager / BIG-IQ / iWorkflow / Traffix SDC

There is no impact for these F5 products; they are not affected by this vulnerability.