Emerging Threathightest
UNC4841 - SSL Certificate Exfiltration Via Openssl
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.
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Launch
Emerging Threat
Active Threat
Developed to detect an active or emerging threat. Prioritize investigation of any alerts and correlate with threat intelligence.
Log Source
LinuxProcess Creation
ProductLinux← raw: linux
CategoryProcess Creation← raw: process_creation
Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.
Detection Logic
Detection Logic1 selector
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: selectionFalse Positives
Unknown
False positive likelihood has not been assessed. Additional context may be needed during triage.
References
MITRE ATT&CK
Tactics
Other
detection.emerging-threats
Rule Metadata
Rule ID
60911c07-f989-4362-84af-c609828ef829
Status
test
Level
high
Type
Emerging Threat
Created
Fri Jun 16
Path
rules-emerging-threats/2023/TA/UNC4841-Barracuda-ESG-Zero-Day-Exploitation/proc_creation_lnx_apt_unc4841_openssl_connection.yml
Raw Tags
attack.defense-evasionattack.t1140detection.emerging-threats