""ET MALWARE Cobalt Strike Beacon Activity (GET)""

SID: 2033145

Revision: 2

Class Type: trojan-activity

Metadata: attack_target Client_Endpoint, created_at 2021_06_15, deployment Perimeter, malware_family Cobalt_Strike, signature_severity Major, updated_at 2021_06_15, mitre_tactic_id TA0011, mitre_tactic_name Command_And_Control, mitre_technique_id T1001, mitre_technique_name Data_Obfuscation

Reference:

• Link

Protocol: tcp

Source Network: $HOME_NET

Source Port: any

Destination Network: $EXTERNAL_NET

Destination Port: $HTTP_PORTS

Flow: established,to_server

Contents:

• Value: "GET"

• Value: ".css?open="

• Value: "lu=" Depth: 3

• Value: !"Referer|3a 20|"

Within:

PCRE: "/^lu=(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=|[A-Za-z0-9+/]{4})$/C"

Special Options:

• http_method

• fast_pattern

• http_uri

• http_cookie

• http_header

source