The dangers of pre-shared key and why a certificate OID is needed. September 2003 The dangers of pre-shared key and why a certificate OID is needed. Arunesh Mishra, Minho Shin, William Arbaugh University of Maryland College Park Insun Lee, Kyunghun Jang Samsung Electronics Mishra, Shin, Arbaugh, Lee, Jang

September 2003 Pre-shared key (PSK) Everyone shares the same PMK therefore we have both an active and a passive attack by insiders. Mishra, Shin, Arbaugh, Lee, Jang

Passive Attack - Eavesdropping September 2003 Passive Attack - Eavesdropping An insider (defined by knowledge of the PSK) can capture the 4-way handshake and derive the PTK allowing them to intercept traffic passively. Mishra, Shin, Arbaugh, Lee, Jang

Active Attack - Man in the middle September 2003 Active Attack - Man in the middle An insider can establish a man in the middle (MiTM) easily. Mishra, Shin, Arbaugh, Lee, Jang

This should not be new to you September 2003 This should not be new to you But- what is interesting is that the same problems exist with the use of certificates, if they are not created properly, i.e. How does the STA know the presented certificate belongs to a AAA server? There is no DNS or IP connectivity to verify the certificates attributes as in TLS. Mishra, Shin, Arbaugh, Lee, Jang

September 2003 Enter the OID MSFT caught this previously in L2TP, fortunately, and carried the prevention technique over to EAP/TLS. XP requires both a server and client OID in certificates: Server: 1.3.6.1.5.5.7.3.1 Client: 1.3.6.1.5.5.7.3.2 STA ONLY accepts a server certificate with the proper OID (Assumes CA only issues OID to AAA servers). Mishra, Shin, Arbaugh, Lee, Jang

September 2003 Recommendation Add informational text to draft explaining the dangers of PSK and strongly suggesting the use of both a server and client OID. Seek approval by the appropriate body of the server and client OIDs. Mishra, Shin, Arbaugh, Lee, Jang

September 2003 Straw Poll Would you approve of informational text that explains the dangers of PSK and strongly suggesting the use of both the server and client OIDS? If the group is in favor, text will be provided by Thursday morning for a vote in the afternoon. Mishra, Shin, Arbaugh, Lee, Jang