Adversary-in-the-Middle
- ID
- T1557
- Tactics
- TA0006 Credential Access, TA0009 Collection
- Platforms
- Linux, macOS, Network Devices, Windows
- Data sources
- Windows Registry Key Modification, Network Connection Creation, File Modification, Network Traffic Content, Application Log Content, Network Traffic Flow
- Source
- attack.mitre.org
- MITRE last modified
- 12 May 2026
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.[1]
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.[2][3][4] 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).[5][6] 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.[7][8][9]
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.
Sub-techniques (4)
- T1557.001 Name Resolution Poisoning and SMB Relay
- T1557.002 ARP Cache Poisoning
- T1557.003 DHCP Spoofing
- T1557.004 Evil Twin
Detection
- DET0296 Detect Adversary-in-the-Middle via Network and Configuration Anomalies
Data components: Windows Registry Key Modification, Network Connection Creation, File Modification, Network Traffic Content, Application Log Content, Network Traffic Flow
Mitigations (7)
- M1017 User Training
Train users to be suspicious about certificate errors. Adversaries may use their own certificates in an attempt to intercept HTTPS traffic. Certificate errors may arise when the application’s certificate does not match the one expected by the host.
- M1030 Network Segmentation
Network segmentation can be used to isolate infrastructure components that do not require broad network access. This may mitigate, or at least alleviate, the scope of AiTM activity.
- M1031 Network Intrusion Prevention
Network intrusion detection and prevention systems that can identify traffic patterns indicative of AiTM activity can be used to mitigate activity at the network level.
- M1035 Limit Access to Resource Over Network
Limit access to network infrastructure and resources that can be used to reshape traffic or otherwise produce AiTM conditions.
- M1037 Filter Network Traffic
Use network appliances and host-based security software to block network traffic that is not necessary within the environment, such as legacy protocols that may be leveraged for AiTM conditions.
- M1041 Encrypt Sensitive Information
Ensure that all wired and/or wireless traffic is encrypted appropriately. Use best practices for authentication protocols, such as Kerberos, and ensure web traffic that may contain credentials is protected by SSL/TLS.
- M1042 Disable or Remove Feature or Program
Disable legacy network protocols that may be used to intercept network traffic if applicable, especially those that are not needed within an environment.