CyberStack

MITRE ATT&CK / Techniques / T1071.003

Application Layer Protocol: Mail Protocols

ID
T1071.003
Tactics
TA0011 Command and Control
Sub-technique of
T1071 Application Layer Protocol
Platforms
Linux, macOS, Network Devices, Windows
Data sources
Network Connection Creation, Process Creation, Network Traffic Content, Network Traffic Flow
Source
attack.mitre.org
MITRE last modified
4 Sep 2026

Adversaries may communicate using application layer protocols associated with electronic mail delivery to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server.

Protocols such as SMTP/S, POP3/S, and IMAP that carry electronic mail may be very common in environments. Packets produced from these protocols may have many fields and headers in which data can be concealed. Data could also be concealed within the email messages themselves. An adversary may abuse these protocols to communicate with systems under their control within a victim network while also mimicking normal, expected traffic.[1]

Detection

Mitigations (2)

M1031 Network Intrusion Prevention

Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary malware can be used to mitigate activity at the network level.

M1037 Filter Network Traffic

Limit the ability of servers and critical systems to initiate outbound email communications. Filtering SMTP/IMAP/POP3 traffic to only trusted mail servers reduces the risk of attackers using compromised systems to exfiltrate data via email or to receive commands from attacker-controlled email accounts.

Groups (6)

Software (20)

References

  1. FireEye APT28