Malicious PDF — malware analysis report

Static analysis result for SHA-256 f98b8b679fb5babf…

MALICIOUS

PDF

127.3 KB
MD5: cbe2b552b441af1f7a58d7133c68bea8 SHA-1: ab12bbdafd0694153aef64356454e8af6cd79eae SHA-256: f98b8b679fb5babfcba99d5ed7db5c3b655e6207cf883131521a337ae9c87318
84 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 JavaScript/JScript T1566.002 Spearphishing Attachment

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings including PDF_JAVASCRIPT and PDF_JS. The ML classifier strongly flags this PDF as malicious. The embedded JavaScript stream, named javascript_obj0013_000.js, is likely responsible for downloading and executing a second-stage payload from one of the suspicious URLs found within the document. The document body content is heavily obfuscated and does not provide clear user-facing lures.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9998

Heuristics 7

  • ASCIIHexDecode filter (with exploit indicators) medium PDF_FILTER_HEX
    Hex-encoding filter present alongside exploit delivery indicators — often used to hide payload or shellcode bytes
  • 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.
  • XFA form low PDF_XFA
    PDF uses XML Forms Architecture — can contain script logic
  • String.fromCharCode low PDF_FROMCHARCODE
    String.fromCharCode found — used to construct payload strings dynamically. Common in benign JavaScript libraries for codepoint manipulation, so this alone is informational; weaponised use is also caught by the dedicated fromCharCode-stage and exploit-shape rules. (matched inside decoded stream)
  • 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.bitstream.com
    • http://ns.adobe.com/xdp/
    • http://www.xfa.org/schema/xci/2.6/
    • http://www.xfa.org/schema/xfa-template/2.6/

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0013_000.js
57daca061d7a81f8fbd743f5357d7b2c0785f0001c8c9ea4799f5e266e002b9b		 pdf-javascript-stream PDF /JS object 13 at offset 0x10531 20836 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
font_00_sfnt_off00000352.bin
a8f4d9b7d604c3c8a0bf3f9a31b9e952d467f98d118fdc784d95d689a14d8a33		 pdf-font-stream PDF embedded font (sfnt) at offset 0x352 65932 bytes

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