Malicious PDF — malware analysis report

Static analysis result for SHA-256 d281b4feda72308f…

MALICIOUS

PDF

198.2 KB Created: 2009-12-16 15:43:47 +08:00 Authoring application: Acrobat PDFMaker 8.0 for Word (via Acrobat Distiller 8.0.0 (Windows))
MD5: eba50a0fbb3b380c45fc642d19c03559 SHA-1: 659e1a6e66a757aba0ca232b5c1838540a6f0702 SHA-256: d281b4feda72308f4a1d343c007e5de7d371aa089007dd380bd0a1688c98983b
188 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell

The PDF file contains obfuscated JavaScript, including calls to eval() and unescape(), which is a strong indicator of malicious intent. A secondary embedded PDF was also detected, which itself contains suspicious static findings. The primary function of the embedded script appears to be downloading and executing a second-stage payload from the embedded PDF. The ML classifier strongly flagged this PDF as malicious.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9997

Heuristics 7

  • Secondary embedded PDF body has suspicious static findings critical POLYGLOT_CHILD_PDF_STATIC_TRIAGE
    A valid PDF body was found at a nonzero offset inside another container and its carved contents matched PDF exploit or lure heuristics. This catches polyglots where the top-level magic routes to ZIP/OLE while a PDF reader or downstream parser opens the hidden PDF payload.
  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • unescape() call high PDF_UNESCAPE
    unescape() found — often used to decode shellcode in PDF JS exploits (matched inside decoded stream)
  • 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.
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://www.w3.org/1999/02/22-rdf-syntax-ns#
    • http://ns.adobe.com/pdf/1.3/
    • http://ns.adobe.com/pdfx/1.3/
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://purl.org/dc/elements/1.1/

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0022_000.js
feac65540d26e56111f21aef62ce780951f37c0c97c12b902e1fc3989c46abad		 pdf-javascript-stream PDF /JS object 22 at offset 0x1922 4677 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 16 eval/decoder/string-building token(s).
polyglot_child_pdf_off0002f6d7.pdf
4bfd8dfb85f361082d8d9290cf9337d5af95e72fe14ba4740cbd0ac889cb28e7		 polyglot-child-pdf Secondary PDF body inside pdf container at offset 0x2F6D7 8685 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 long base64-like blob(s).

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