""ET INFO Base64 Encoded Null Byte Padded File in HTML Body (Magic Bytes)""

SID: 2047791

Revision: 1

Class Type: misc-activity

Metadata: attack_target Client_Endpoint, created_at 2023_08_28, deployment Perimeter, deployment SSLDecrypt, performance_impact Low, confidence High, signature_severity Informational, tag HTML_Smuggling, updated_at 2023_10_06, reviewed_at 2023_08_28, mitre_tactic_id TA0005, mitre_tactic_name Defense_Evasion, mitre_technique_id T1027, mitre_technique_name Obfuscated_Files_or_Information

Reference:

Protocol: tcp

Source Network: $EXTERNAL_NET

Source Port: $HTTP_PORTS

Destination Network: $HOME_NET

Destination Port: any

Flow: established,to_client

Contents:

  • Value: "data|3a|"

  • Value: "base64,AAAAAAAA"

Within: 65

PCRE:

Special Options:

  • file_data

  • nocase

  • fast_pattern

source