Malicious PDF — malware analysis report

Static analysis result for SHA-256 1b3333c76dc9464b…

MALICIOUS

PDF

52.8 KB Created: 2017-11-13 00:19:06 +01:00
MD5: d893280b50e85f8b68096bab5de08cd3 SHA-1: fd0843af421ba0775cccd88af0e7ae1542aa0e26 SHA-256: 1b3333c76dc9464bfcbe92a522f4a4270cd13409bdfc28bda1a9a6b5d4016e9d
138 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 JavaScript/JScript T1204.002 Malicious File T1566.001 Spearphishing Attachment

The PDF contains embedded JavaScript with eval() calls and String.fromCharCode, indicating obfuscated code execution. Heuristics also flag an embedded script payload and a general ML classification of malicious. The JavaScript is likely responsible for downloading and executing a secondary payload, though the specific URLs or commands are not directly extractable from the provided evidence.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9729

Heuristics 9

  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
  • Embedded script payload in PDF stream medium PDF_EMBEDDED_SCRIPT_PAYLOAD
    PDF stream bytes contain an HTML/XFA <script> tag without accompanying Windows shell-execution primitives — common in accessible XFA forms but worth surfacing for analyst review.
  • Embedded file low PDF_EMBEDDED
    PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload
  • XFA form low PDF_XFA
    PDF uses XML Forms Architecture — can contain script logic
  • 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. (matched inside decoded stream)
  • 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. (matched inside decoded stream)
  • 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)
  • AcroForm button with action trigger low PDF_ACROFORM_BUTTON
    PDF contains a /Btn form field together with a SubmitForm/URI/Launch/JS trigger — this is the building block of fake 'Download' or 'Open' button overlays used in PDF phishing lures
  • 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/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
embedded_file_obj0029.bin
ddb2f0273ff53a78cba698afed0c23add8e219eaa85fecd99611493bebdb4d27		 pdf-embedded-file PDF EmbeddedFile object 29 at offset 0xC668 1237 bytes
objstm_0035_00.bin
eeb69e2dadfa00e86ba6af0e6cb511413051e5b08feb63db3edbb93a1dcfb2ad		 pdf-objstm-decoded PDF /ObjStm 35 0 obj (inflated) 1283 bytes

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