Cross-source coverage

T1048.001 / ATT&CK

Exfiltration Over Alternative Protocol: Exfiltration Over Symmetric Encrypted Non-C2 Protocol

5 rules across 3 sources.

From MITRE ATT&CK 19.2

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).

Tactics
Exfiltration
Platforms
Linux · macOS · Windows · ESXi
Telemetry
WinEventLog:Sysmonauditd:SYSCALLNSM:Flowmacos:unifiedlogmacos:osqueryesxi:vmkernelesxi:hostd

How MITRE says to detect it DET0503

Behavioral Detection Strategy for Exfiltration Over Symmetric Encrypted Non-C2 Protocol

Windows Analytic 1389

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.

  • WinEventLog:Sysmon EventCode=3, 22
  • WinEventLog:Sysmon EventCode=1

Linux Analytic 1390

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.

  • auditd:SYSCALL execve
  • auditd:SYSCALL connect
  • NSM:Flow conn.log or flow data
  • NSM:Flow ssl.log (for TLS handshake analysis), dns.log (tunneling indicators)

macOS Analytic 1391

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.

  • macos:unifiedlog log stream process subsystem
  • macos:osquery socket_events
  • macos:unifiedlog log stream network activity

ESXi Analytic 1392

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).

  • esxi:vmkernel egress log analysis
  • esxi:hostd execution + payload hints
  • NSM:Flow host switch egress data

View on attack.mitre.org ↗

Wazuh Core Ruleset

3 rules
Detection Severity Format
Amazon Security Lake - Amazon VPC rules grouped. Low Wazuh XML
Amazon Security Lake - CloudTrail rules grouped. Low Wazuh XML
Amazon Security Lake - Route 53 rules grouped. Low Wazuh XML

SigmaHQ/sigma

1 rule
Detection Severity Format
DNS Exfiltration and Tunneling Tools Execution High Sigma

elastic/detection-rules

1 rule
Detection Severity Format
Potential Data Exfiltration Through Curl Medium Elastic TOML

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