Malicious PDF — malware analysis report

Static analysis result for SHA-256 81c5251dd0446f21…

MALICIOUS

PDF

31.6 KB Created: ·P’ò%$;ý§Y¶ú0¯D ³‚›%2& Authoring application: • f  – „½ùtK (via • ’f ª– „¼õt\ ñ)
MD5: 3d30381f5deffeba28742f9a5a741bc8 SHA-1: 645e7c1fe7039b38645bbf1153a012eee290eb99 SHA-256: 81c5251dd0446f2198c39c0f4bc1d5616b97e79a8fcea1de32c8f5fa0f0a9605
64 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell

The PDF file is encrypted and contains embedded JavaScript, which is a common technique to obfuscate malicious content. The presence of JavaScript actions and an embedded JS stream, combined with the PDF encryption using JavaScript, strongly suggests that the script is responsible for delivering the malicious payload. The script itself is large and likely contains the core malicious functionality, such as downloading and executing further stages. The specific intent of the script could not be fully determined due to its size and potential obfuscation, but its presence within an encrypted PDF points to a delivery mechanism for malware.

Heuristics 4

  • Encrypted PDF carries /JavaScript — payload hidden from static analysis high PDF_ENCRYPTED_WITH_JS
    PDF declares /Encrypt and also references an executable trigger (/JavaScript). Document encryption hides the JavaScript body and stream contents from static scanners — combined with auto-execution indicators this is a known evasion pattern used to deliver weaponised JavaScript that the analyst cannot inspect without the decryption key.
  • JavaScript action low PDF_JAVASCRIPT
    PDF contains a /JavaScript action. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • Embedded JS stream low PDF_JS
    PDF references a /JS stream. Generic JavaScript is common in benign forms; specific dangerous APIs are scored by separate rules.
  • Optional Content Group with action trigger low PDF_OPTIONAL_CONTENT
    Optional Content Group (layer) co-occurs with an action trigger — content can be selectively hidden from viewers or scanners while the action still fires on open

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0009_000.js
2e116e8e6421df713a659a929372f329bd31499d8b851782618aee87eac6a624		 pdf-javascript-stream PDF /JS object 9 at offset 0x3D2 29722 bytes

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