Malicious PDF — malware analysis report

Static analysis result for SHA-256 5f74508f89d65396…

MALICIOUS

PDF

8.3 KB
MD5: 55e4030f0090296567d86e2a7ab3df6e SHA-1: dc910e5c35c012589fecfabe10e61fd9bc325d12 SHA-256: 5f74508f89d6539608a0306cbb1a78498238c42aa7fc5687543e67fad5c95e09
158 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The PDF contains obfuscated JavaScript, indicated by PDF_JAVASCRIPT and PDF_JS heuristics, which utilizes eval() and String.fromCharCode. This JavaScript is likely responsible for downloading and executing a secondary payload, as suggested by the PDF_JS_EXPLOIT_CLUSTER firing. The ML classifier also flagged the PDF as malicious with a high probability. No specific family could be identified.

Machine Learning

  • Nyx PDF Classifier malicious score 0.8287

Heuristics 7

  • PDF JavaScript exploit cluster critical PDF_JS_EXPLOIT_CLUSTER
    PDF combines an executable JavaScript/action surface with exploit staging indicators such as eval/unescape/fromCharCode, XFA script content, or a related CVE pattern. Benign form JavaScript remains low-severity, but this correlated cluster is high-confidence malicious behavior.
  • eval() call high PDF_EVAL
    eval() found — commonly used for obfuscated exploit execution (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. (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)
  • 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/xap/1.0/
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://ns.adobe.com/pdf/1.3/

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
stream_003_off000004a7.bin
8505f10ea09728a0b8061e075f08305459e5e3c53453a51cfcdb1922310e1722		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0x4A7 2438 bytes
stream_004_off00000b74.js
72976bee7b057c9d715415314d451ee25a9862b4b3f68da1b805b85fdca17bf5		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0xB74 366 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 1 eval/decoder/string-building token(s).
objstm_0026_00.bin
7b72b9a02bdaa8e51a9b0074a50985b1b1873eedcfa2a5252b5a4698cec00d89		 pdf-objstm-decoded PDF /ObjStm 26 0 obj (inflated) 468 bytes

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