Adversary-in-the-Middle

What the technique is

Adversaries may attempt to position themselves between two or more networked devices using an adversary-in-the-middle (AiTM) technique to support follow-on behaviors such as Network Sniffing, Transmitted Data Manipulation, or replay attacks (Exploitation for Credential Access). By abusing features of common networking protocols that can determine the flow of network traffic (e.g. ARP, DNS, LLMNR, etc.), adversaries may force a device to communicate through an adversary controlled system so they can collect information or perform additional actions. For example, adversaries may manipulate victim DNS settings to enable other malicious activities such as preventing/redirecting users from accessing legitimate sites and/or pushing additional malware. Adversaries may also manipulate DNS and leverage their position in order to intercept user credentials, including access tokens (Steal Application Access Token) and session cookies (Steal Web Session Cookie). Downgrade Attacks can also be used to establish an AiTM position, such as by negotiating a less secure, deprecated, or weaker version of communication protocol (SSL/TLS) or encryption algorithm. Adversaries may also leverage the AiTM position to attempt to monitor and/or modify traffic, such as in Transmitted Data Manipulation. […]

What MITRE says you would watch

• AN0823

  Detects suspicious DNS/ARP poisoning attempts, unauthorized modifications to registry/network configuration, or abnormal TLS downgrade activity. Correlates changes in system configuration with subsequent unusual network flows or authentication events.

• AN0824

  Detects unauthorized edits to /etc/hosts, /etc/resolv.conf, or suspicious ARP broadcasts. Correlates file modifications with subsequent unexpected network sessions or service creation.

• AN0825

  Detects unauthorized edits to system configuration profiles, unexpected certificate trust changes, or abnormal ARP/DNS patterns indicative of interception.