UNC4841 - SSL Certificate Exfiltration Via Openssl

title: UNC4841 - SSL Certificate Exfiltration Via Openssl
id: 60911c07-f989-4362-84af-c609828ef829
status: test
description: Detects the execution of "openssl" to connect to an IP address. This techniques was used by UNC4841 to exfiltrate SSL certificates and as a C2 channel with named pipes. Investigate commands executed in the temporal vicinity of this command.
references:
    - https://www.mandiant.com/resources/blog/barracuda-esg-exploited-globally
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-06-16
tags:
    - attack.stealth
    - attack.t1140
    - detection.emerging-threats
logsource:
    product: linux
    category: process_creation
detection:
    selection:
        Image|endswith: '/openssl'
        CommandLine|re: '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'
        CommandLine|contains|all:
            - 's_client'
            - '-quiet'
            - '-connect'
        CommandLine|contains:
            - ':443'
            - ':8080'
    condition: selection
falsepositives:
    - Unknown
level: high