| ID | Name |
|---|---|
| T1048.001 | Exfiltration Over Symmetric Encrypted Non-C2 Protocol |
| T1048.002 | Exfiltration Over Asymmetric Encrypted Non-C2 Protocol |
| T1048.003 | Exfiltration Over Unencrypted Non-C2 Protocol |
Adversaries may steal data by exfiltrating it over a symmetrically encrypted network protocol other than that of the existing command and control channel. The data may also be sent to an alternate network location from the main command and control server.
Symmetric encryption algorithms are those that use shared or the same keys/secrets on each end of the channel. This requires an exchange or pre-arranged agreement/possession of the value used to encrypt and decrypt data.
Network protocols that use asymmetric encryption often utilize symmetric encryption once keys are exchanged, but adversaries may opt to manually share keys and implement symmetric cryptographic algorithms (ex: RC4, AES) vice using mechanisms that are baked into a protocol. This may result in multiple layers of encryption (in protocols that are natively encrypted such as HTTPS) or encryption in protocols that not typically encrypted (such as HTTP or FTP).
| ID | Mitigation | Description |
|---|---|---|
| M1037 | Filter Network Traffic |
Enforce proxies and use dedicated servers for services such as DNS and only allow those systems to communicate over respective ports/protocols, instead of all systems within a network. |
| M1031 | Network Intrusion Prevention |
Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary command and control infrastructure and malware can be used to mitigate activity at the network level. |
| M1030 | Network Segmentation |
Follow best practices for network firewall configurations to allow only necessary ports and traffic to enter and exit the network.[1] |
| ID | Name | Analytic ID | Analytic Description |
|---|---|---|---|
| DET0503 | Behavioral Detection Strategy for Exfiltration Over Symmetric Encrypted Non-C2 Protocol | AN1389 |
Detects the execution of non-browser processes establishing outbound encrypted network connections using uncommon symmetric encryption protocols (e.g., AES via PowerShell or custom scripts) to alternate external destinations. |
| AN1390 |
Detects command-line utilities or scripts using encryption libraries or symmetric algorithms (e.g., OpenSSL AES, GPG, Python + PyCrypto) in conjunction with outbound file transfers or traffic to external destinations. |
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| AN1391 |
Detects symmetric key-based encryption operations (e.g., AES via Python, AppleScript, or OpenSSL) followed by unusual outbound connections from non-browser applications or scripted tools. |
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| AN1392 |
Detects unexpected encrypted egress traffic from management services (e.g., hostd) or guest VMs utilizing symmetric encryption without traditional protocols (e.g., FTP with embedded AES ciphertext). |