Malicious PDF — malware analysis report

Static analysis result for SHA-256 143278d7fa86fc80…

MALICIOUS

PDF

6.4 KB
MD5: 856174aa3488466d640b2b8f6df7ec81 SHA-1: 64c19b3e30ca89417ef0da868621a6f5c1667ad4 SHA-256: 143278d7fa86fc8072f4c38624f37c51bf2a85a7a5688dcd7c6058a37bef8fc0
148 Risk Score

Malware Insights

MITRE ATT&CK
T1059.007 JavaScript T1203 Exploitation for Client Execution

The PDF sample contains embedded JavaScript, flagged by multiple heuristics including PDF_JAVASCRIPT and PDF_JS_EXPLOIT_CLUSTER. The presence of an unescape() call within the JavaScript stream indicates an attempt to decode and execute malicious code, likely leading to client-side exploitation. No specific family could be identified, but the technique suggests a downloader or dropper.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9833

Heuristics 5

  • 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.
  • 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. (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)
  • 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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objstm_0024_00.bin
1c43b33894112743b33db26424087cb70a2314937a9592688d803e9ce6ed314d		 pdf-objstm-decoded PDF /ObjStm 24 0 obj (inflated) 500 bytes

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