Suspicious SSL Connection — Sigma Rule

Rule metadata and linked tags

Author: frack113. Source status: test; severity: low. Source dates: 2022-01-23 / not supplied.

{
  "product": "windows",
  "category": "ps_script",
  "definition": "Requirements: Script Block Logging must be enabled"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: a5b7e19bef10c2ca0541649f39024a6d910d26962040a071a48c2ce187aa1dc3

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Suspicious SSL Connection
id: 195626f3-5f1b-4403-93b7-e6cfd4d6a078
status: test
description: Adversaries may employ a known encryption algorithm to conceal command and control traffic rather than relying on any inherent protections provided by a communication protocol.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1573/T1573.md#atomic-test-1---openssl-c2
    - https://medium.com/walmartglobaltech/openssl-server-reverse-shell-from-windows-client-aee2dbfa0926
author: frack113
date: 2022-01-23
tags:
    - attack.command-and-control
    - attack.t1573
logsource:
    product: windows
    category: ps_script
    definition: 'Requirements: Script Block Logging must be enabled'
detection:
    selection:
        ScriptBlockText|contains|all:
            - System.Net.Security.SslStream
            - Net.Security.RemoteCertificateValidationCallback
            - '.AuthenticateAsClient'
    condition: selection
falsepositives:
    - Legitimate administrative script
level: low

Original YAML and metadata in JSON

False positives

• Legitimate administrative script

Source references

• https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1573/T1573.md#atomic-test-1---openssl-c2
• https://medium.com/walmartglobaltech/openssl-server-reverse-shell-from-windows-client-aee2dbfa0926