T1557 - Adversary-in-the-Middle

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.(Citation: Rapid7 MiTM Basics)

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.(Citation: ttint_rat)(Citation: dns_changer_trojans)(Citation: ad_blocker_with_miner) Adversaries may also manipulate DNS and leverage their position in order to intercept user credentials and session cookies.(Citation: volexity_0day_sophos_FW) 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.(Citation: mitm_tls_downgrade_att)(Citation: taxonomy_downgrade_att_tls)(Citation: tlseminar_downgrade_att)

Adversaries may also leverage the AiTM position to attempt to monitor and/or modify traffic, such as in Transmitted Data Manipulation. Adversaries can setup a position similar to AiTM to prevent traffic from flowing to the appropriate destination, potentially to Impair Defenses and/or in support of a Network Denial of Service.

Atomic Tests:

Currently, no tests are available for this technique.

Detection

Monitor network traffic for anomalies associated with known AiTM behavior. Consider monitoring for modifications to system configuration files involved in shaping network traffic flow.

Shield Active Defense

Network Monitoring

Monitor network traffic in order to detect adversary activity.

Network monitoring involves capturing network activity data, including capturing of server, firewall, and other relevant logs. A defender can then review them or send them to a centralized collection location for further analysis.

Opportunity

There is an opportunity to monitor network traffic for different protocols, anomalous traffic patterns, transfer of data, etc. to determine the presence of an adversary.

Use Case

A defender can monitor network traffic for anomalies associated with known MiTM behavior.

Procedures

Capture network logs for internet-facing devices and send those logs to a central collection location. Capture all network device (router, switches, proxy, etc.) logs on a decoy network and send those logs to a central collection location.