Malicious PDF — malware analysis report

Static analysis result for SHA-256 5c7edd36b131f3cf…

MALICIOUS

PDF

750.2 KB Created: 2008-07-17 23:28:44 +08:00 Authoring application: Acrobat PDFMaker 7.0 for Word (via Acrobat Distiller 7.0 (Windows))
MD5: 71f8ec14981d7ade3fa787ad85fd60c9 SHA-1: 5cc994c4d7e5a42272496520472da2ff9e5eb19c SHA-256: 5c7edd36b131f3cf6d48ab966b96d0bf9a49e292a362f503774de1f370790c8a
228 Risk Score

Malware Insights

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

The PDF contains embedded JavaScript that utilizes eval() and String.fromCharCode() functions, indicating an attempt to obfuscate malicious code. The script also checks the Adobe Reader version, suggesting it's exploiting a known vulnerability for client execution. The primary goal appears to be downloading and executing a secondary payload, likely delivered as a spearphishing attachment.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9972

Heuristics 10

  • 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.
  • Secondary embedded PDF body has suspicious static findings critical POLYGLOT_CHILD_PDF_STATIC_TRIAGE
    A valid PDF body was found at a nonzero offset inside another container and its carved contents matched PDF exploit or lure heuristics. This catches polyglots where the top-level magic routes to ZIP/OLE while a PDF reader or downstream parser opens the hidden PDF payload.
  • 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.
  • 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.
  • Embedded file low PDF_EMBEDDED
    PDF embeds a file attachment — could carry an executable or another weaponised document as a nested payload
  • 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)
  • Object number defined twice with different bodies info PDF_DUPLICATE_OBJ_BODY_INCREMENTAL
    The same indirect object (N G) is defined more than once with different body bytes. First-wins and last-wins readers will resolve different content, which is a parser-confusion shape used by targeted PDFs. Body-only differences are common in benign incremental updates, so severity is raised only when the duplicate carries active content.
  • 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/pdf/1.3/
    • http://ns.adobe.com/pdfx/1.3/
    • http://ns.adobe.com/xap/1.0/
    • http://ns.adobe.com/xap/1.0/mm/
    • http://purl.org/dc/elements/1.1/
    • http://ns.adobe.com/photoshop/1.0/

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
3.jpg
5d6527b148e8d84a27a4f669d817a52d39abe9bec61e35a052c66d495101c827		 pdf-embedded-file PDF EmbeddedFile object 31 at offset 0x2303 403 bytes
javascript_obj0037_000.js
98e3c3ca0476ffedc3c2fffc3d2bff11646ce68d12d65706966657d0d9c107a5		 pdf-javascript-stream PDF /JS object 37 at offset 0xBA204 3433 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s).
polyglot_child_pdf_off00030ed0.pdf
7261617645f4447dcd9dcdb452342e0813e39ab371a40229a14d53033fe93aae		 polyglot-child-pdf Secondary PDF body inside pdf container at offset 0x30ED0 567761 bytes

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