An adversary targets the communication between two components (typically client and server), in order to alter or obtain data from transactions. A general approach entails the adversary placing themself within the communication channel between the two components.

Whenever one component attempts to communicate with the other (data flow, authentication challenges, etc.), the data first flows through the adversary, who has the opportunity to observe or alter it, before being passed on to the intended recipient as if it was never observed. This interposition is transparent leaving the two compromised components unaware of the potential corruption or leakage of their communications. The potential for these attacks yields an implicit lack of trust in communication or identify between two components.
These attacks differ from Sniffing Attacks (CAPEC-157) since these attacks often modify the communications prior to delivering it to the intended recipient.

Man-in-the-Middle / MITM

Person-in-the-Middle / PiTM

Monkey-in-the-Middle

Monster-in-the-Middle

On-path Attacker

High
Very High

1
Explore
[Determine Communication Mechanism] The adversary determines the nature and mechanism of communication between two components, looking for opportunities to exploit.
Perform a sniffing attack and observe communication to determine a communication protocol.
Look for application documentation that might describe a communication mechanism used by a target.

2
Experiment
[Position In Between Targets] The adversary inserts themself into the communication channel initially acting as a routing proxy between the two targeted components.
Install spyware on a client that will intercept outgoing packets and route them to their destination as well as route incoming packets back to the client.
Exploit a weakness in an encrypted communication mechanism to gain access to traffic. Look for outdated mechanisms such as SSL.

3
Exploit
[Use Intercepted Data Maliciously] The adversary observes, filters, or alters passed data of its choosing to gain access to sensitive information or to manipulate the actions of the two target components for their own purposes.
Prevent some messages from reaching their destination, causing a denial of service.

There are two components communicating with each other.
An attacker is able to identify the nature and mechanism of communication between the two target components.
An attacker can eavesdrop on the communication between the target components.
Strong mutual authentication is not used between the two target components yielding opportunity for attacker interposition.
The communication occurs in clear (not encrypted) or with insufficient and spoofable encryption.

This attack can get sophisticated since the attack may use cryptography.

Integrity
Modify Data

Confidentiality
Access Control
Authorization
Gain Privileges

Confidentiality
Read Data

Ensure Public Keys are signed by a Certificate Authority
Encrypt communications using cryptography (e.g., SSL/TLS)
Use Strong mutual authentication to always fully authenticate both ends of any communications channel.
Exchange public keys using a secure channel

In 2017, security researcher Jerry Decime discovered that Equifax mobile applications were not leveraging HTTPS in all areas. Although authentication was properly utilizing HTTPS, in addition to validating the root of trust of the server certificate, other areas of the application were using HTTP to communicate. Adversaries could then conduct MITM attacks on rogue WiFi or cellular networks and hijack the UX. This further allowed the adversaries to prompt users for sensitive data, which could then be obtained in the plaintext response. [REF-636]

1557
Adversary-in-the-Middle

Man-in-the-middle attack

CAPEC Content Team
The MITRE Corporation
2014-06-23

CAPEC Content Team
The MITRE Corporation
2017-08-04
Updated Examples-Instances, Related_Vulnerabilities

CAPEC Content Team
The MITRE Corporation
2018-07-31
Updated References

CAPEC Content Team
The MITRE Corporation
2019-04-04
Updated Example_Instances, Related_Attack_Patterns, Taxonomy_Mappings

CAPEC Content Team
The MITRE Corporation
2019-09-30
Updated @Abstraction, Description, Related_Attack_Patterns

CAPEC Content Team
The MITRE Corporation
2020-07-30
Updated Description, Example_Instances, Execution_Flow, Taxonomy_Mappings

CAPEC Content Team
The MITRE Corporation
2020-12-17
Updated Related_Attack_Patterns, Taxonomy_Mappings

CAPEC Content Team
The MITRE Corporation
2021-06-24
Updated @Name, @Status, Alternate_Terms, Description, Example_Instances, Execution_Flow, Mitigations, References, Related_Attack_Patterns, Related_Weaknesses, Taxonomy_Mappings

CAPEC Content Team
The MITRE Corporation
2022-02-22
Updated Description, Execution_Flow, Extended_Description

CAPEC Content Team
The MITRE Corporation
2022-09-29
Updated Taxonomy_Mappings

Man in the Middle Attack