Malicious PDF — malware analysis report

Static analysis result for SHA-256 831e3ba177aa3d5d…

MALICIOUS

PDF

8.2 KB
MD5: 049b878698a880f89ffe63ced50687bc SHA-1: fdde269485f0c98ca6d5c6311edd4101cf51dfed SHA-256: 831e3ba177aa3d5d665ca3c7b7458300259c99af9e6a357135f7930cb4c058b4
156 Risk Score

Malware Insights

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

The PDF file contains JavaScript code that utilizes eval() and String.fromCharCode, indicating an attempt to obfuscate malicious actions. This JavaScript is likely designed to download and execute a secondary payload, a common technique for initial compromise. The ML classifier also flagged this PDF as malicious with high confidence.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9164

Heuristics 6

  • 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)
  • 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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
stream_002_off0000032d.bin
8505f10ea09728a0b8061e075f08305459e5e3c53453a51cfcdb1922310e1722		 decompressed-pdf-stream PDF FlateDecoded stream at offset 0x32D 2438 bytes
objstm_0025_00.bin
d7311601f2db6ba9bf96e40f9d9632076494465f99e5da222bd808f1409606df		 pdf-objstm-decoded PDF /ObjStm 25 0 obj (inflated) 546 bytes

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