On the security of PPPoE network

Abstract

Point‐to‐Point Protocol over Ethernet (PPPoE) is a network protocol for encapsulating PPP frames inside Ethernet frames. It is widely used by commercial Internet service providers to provide Internet surfing for customers who pay bills. In this paper, we analyze the security of PPPoE network. We find that we can easily collect information about both the peers and the PPPoE authentication servers. We can use such information to recover the peer's authentication password by silently impersonating the server, which is undetectable in the network. We impersonate the server in the peers' LAN and get their passwords by hijacking the peers' PPPoE connections and negotiating for using the Password Authentication Protocol (PAP). We further propose an efficient password recovery attack against the Challenge‐Handshake Authentication Protocol (CHAP). We first recover the length of the used password through on‐line queries, based on the weakness of MD5 input pre‐processing. Then, we crack the known‐length password off‐line, using the probabilistic context‐free grammars. We point out that PPPoE cannot be used anymore until all of the weak authentication protocols including PAP, CHAP, and Microsoft CHAP are abolished right now and replaced with more secure Extensible Authentication Protocols. Copyright © 2012 John Wiley & Sons, Ltd.

A General Way to Break Hash-based Challenge-and-Response

“…CHAP. The Challenge-Handshake Authentication Protocol (CHAP) [3], [8], [9] is an authentication scheme used by a PPP server to validate the identity of a remote peer, who wants to access the resource of the server. The server sends an id and a challenge C to the peer.…”

Design in the Authentication and Billing System Based on Radius and 802.1x Protocol

“…Ping Ding considered that the 802.1x misses its goals in access control denial of service (DoS) attacks and propose a Central Manager (CM) not only to take the responsibility of an authentication server, but also to add functionality to prevent denial of service attacks [1]; Pascal Urien and Guy Pujolle introduced smart cards ensuring strong authentication in IP networks, according to the extensible authentication protocol (EAP) [2]; Fanbao Liu and Yumeng Feng have a study on the security problem of PPPoE network [3]; Gaurav Sharma made use of currency like hash chain tokens in order to identify an efficient authentication and billing mechanism for faster handoffs in WLANs based on the IEEE 802.1x specification [4]. This paper not only compares the advantages and disadvantages between different internet protocols but also propose a solution integrate both of International Symposium on Computers & Informatics (ISCI 2015) the advantage of 802.1x and radius in order to the network protocol overhead and improve the network performance.…”

How to Break EAP-MD5

“…The authenticator is a network device, such as a Wireless Access Point (WAP), and the authentication server is typically a host running software supporting the Remote Authentication Dial In User Service (RADIUS) and EAP protocols. EAP-MD5 [4], first used as Challenge-Handshake Authentication Protocol (CHAP) [13] in Point-to-Point Protocol (PPP) [12,9] network for peer authentication, is a hash-based challenge and response protocol. EAP-MD5 applies the secret prefix approach of hashing [14] to generate response R = MD5(P ||C), where P is the shared password and C is the challenge.…”