| Internet-Draft | MITM | October 2022 |
| Richardson & Hoyland | Expires 26 April 2023 | [Page] |
The terms on-path attacker and Man-in-the-Middle Attack have been used in a variety of ways, sometimes interchangeably, and sometimes meaning different things.¶
This document offers an update on terminology for network attacks. A consistent set of terminology is important in describing what kinds of attacks a particular protocol defends against, and which kinds the protocol does not.¶
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A number of terms have been used to describe attacks against networks.¶
In the [dolevyao] paper, the attacker is assumed to be able to:¶
Some authors refer to such an attacker as an "on-path" attacker [reference], or a "Man-in-the-Middle" [reference]. This type of attack is also refered to as a "monster-in-the-middle" attack.¶
Despite a broad consensus on what is meant by a MITM attack, there is less agreement on the how to describe its variants. The term "passive attacker" has been used in many cases to describe situations where the attacker can only observe messages, but can not intercept, modify or delete any messages.¶
Another variant is the case where an eavesdropper is not on the network path between the actual correspondants, and thus cannot drop messages, they may be able to inject packets faster than the correspondants, and thus beat legitimate packets in a race.¶
As summarised, there are three broad variations of the MITM attacker:¶
The attacks are numbered in this section as no consensus on naming the attacks yet. In the diagrams below, the sender is named "Alice", and the recipient is named "Bob", as is typical in many cryptographic protocols [alicebob], as first introduced by [digisign].¶
The attacker is named "Mallory"¶
In this attack, the attacker is involved with the forwarding of the packets. A firewall or network router is ideally placed for this attack.¶
In this case Mallory can:¶
In this attack, the attacker is not involved with the forwarding of the packets. The attacker receives a copy of packets that are sent. This could be from, for instance, a mirror port or SPAN [span]. Alternatively, a copy of traffic may be obtained via passive (optical) tap [fibertap]. This kind of attack is often associated with Pervasive Monitoring [RFC7258].¶
In this case Mallory can:¶
In some cases, Mallory may be able to send messages to Bob via another route which due to some factor will arrive at Bob prior to the original message from Alice.¶
In that case Mallory can:¶
But Mallory will be unable to drop or modify the original packets. Bob however, may be unable to distinguish packets from Alice vs packets sent from Mallory that purport to be from Alice.¶
The third kind of attack is one in which Mallory can not see any packets from Alice. This is usually what is meant by an "off-path" attack. Mallory can usually forge packets purporting to be from Alice, but can never see Alice's actual packets.¶
In this case Mallory can:¶
This document aspires to pick a single set of terms and explain them.¶
Alternatively:¶
[alliteration] proposes the "the council of attackers"¶
This document introduces a set of terminology that will be used in many Security Considerations sections.¶
This document makes no IANA requests.¶
The SAAG mailing list.¶