sublimemediumRule

Attachment: PDF with base64 JavaScript and eval functions

PDF attachment contains base64-encoded JavaScript variables with eval functions, indicating potential code obfuscation and execution techniques commonly used in malicious documents.

MITRE ATT&CK

T1566.001 T1204.002 T1486 T1036 T1027

defense-evasion

Detection Query

type.inbound
and any(filter(attachments, .file_type == "pdf"),
        any(file.explode(.),
            .depth == 0
            and any(.scan.yara.matches, .name in ("pdf_b64_js_var_eval", ))
        )
)

Data Sources

Email MessagesEmail HeadersEmail Attachments

Platforms

Raw Content

name: "Attachment: PDF with base64 JavaScript and eval functions"
description: "PDF attachment contains base64-encoded JavaScript variables with eval functions, indicating potential code obfuscation and execution techniques commonly used in malicious documents."
type: "rule"
severity: "medium"
source: |
  type.inbound
  and any(filter(attachments, .file_type == "pdf"),
          any(file.explode(.),
              .depth == 0
              and any(.scan.yara.matches, .name in ("pdf_b64_js_var_eval", ))
          )
  )

attack_types:
  - "Malware/Ransomware"
tactics_and_techniques:
  - "Evasion"
  - "PDF"
detection_methods:
  - "File analysis"
  - "Javascript analysis"
  - "YARA"
id: "7fa9cfb5-c043-58b0-8914-d726222073b2"