Cupid is the name of the new Heartbleed attack method recently proposed by Portuguese security researcher Luis Grangeia, unlike the original version of the attack, which took place on TLS connections over TCP, it could be exploited over wireless networks and peer-to-peer connections. The Cupid attack happens on TLS connections over the Extensible Authentication Protocol (EAP), the popular authentication framework typically used in wireless networks and peer-to-peer connections, in particular the HeartBleed flaw impacted EAP methods are the ones that use TLS (EAP-PEAP, EAP-TLS and EAP-TTLS). EAP-PEAP, EAP-TTLS and EAP-TLS use a TLS tunnel over EAP to secure some part of the authentication process.
As explained by the researcher Cupid is the name he gave to two source patches that can be applied to the programs “hostapd” and “wpa_supplicant” on Linux, they attempt to exploit Heartbleed over EAP TLS tunneled protocols EAP-PEAP, EAP-TLS, EAP-TTLS and affects both clients and servers.
“This is basically the same attack as heartbleed, based on a malicious heartbeat packet. Like the original attack which happens on regular TLS connections over TCP, both clients and servers can be exploited and memory can be read off processes on both ends of the connection. The difference in this scenario is that the TLS connection is being made over EAP, which is an authentication framework/mechanism used in Wireless networks. It’s also used in other situations, including wired networks that use 802.1x Network Authentication and peer to peer connections.” said Luis Grangeia.
In successfully attacks, hackers can gain access to the contents of the memory exactly like in the HeartBleed scenario, and steal the private key of the certificate used on the TLS connection, and authentication credentials.
As explained by Grangeia the Cupid attack vectors are:
In the attack scenario 1 servers could be attacked by evil client that relies on an altered version of the wpa_supplicant application to handle authentication on a WiFi communication. The attacker requests a connection to a vulnerable network and then send a Heartbeat request right after the TLS connection is made.
In the attack scenario 2 vulnerable clients can be exploited with the modified hostapd application which is designed for deploying configurable Access Points on Linux. The attacker sets up a network that sends malicious heartbeat requests when a vulnerable client requests a TLS connection.
“We request a connection to a vulnerable network and then send a heartbeat request right after the TLS connection is made,” Grangeia explained in his report.
Be aware, as explained by the researcher, the attacker doesn’t need a valid password to exploit the flaw, it is enough only a valid username, it’s also not necessary to establish a full TLS connection in order to perform a Cupid attack since heartbeat responses can be sent or received before keys and certificates are exchanged.
Which systems are vulnerable to the Cupid attack?
Luis Grangeia explained that default installations of wpa_supplicant, hostapd, and freeradius can be exploited on Ubuntu if it uses a vulnerable version of OpenSSL, while Mobile devices running Android 4.1.0 and 4.1.1 are affected because they use wpa_supplicant to connect to wireless networks.
Grangeia revealed that 802.1x Network Access Controlled wired networks could be impacted, but the good news is that home routers don’t use EAP.
Be aware, everything that uses OpenSSL for EAP TLS is susceptible to Cupid attacks, so don’t waste time the Cupid patches for hostapd and wpa_supplicant are available on GitHub.
(Security Affairs – Cupid attack, HeartBleed)