Malicious PDF — malware analysis report

Static analysis result for SHA-256 cb79cf378583e1cf…

MALICIOUS

PDF

23.6 KB
MD5: 7a2433496384bc21221643a9c6ba056a SHA-1: f1e8116fae731c74edef9164f4d146174191a0bf SHA-256: cb79cf378583e1cf89531673a116c4acf76c960b73a77ee8a6b2ec3f0b8d52be
120 Risk Score

Malware Insights

MITRE ATT&CK
T1059.001 PowerShell T1204.002 Malicious File

The PDF contains embedded JavaScript that is heavily obfuscated, but static analysis indicates it's part of an exploit cluster. The ML classifier strongly flags this PDF as malicious. The deobfuscated JavaScript likely downloads and executes a second-stage payload, which is a common technique for initial access.

Machine Learning

  • Nyx PDF Classifier malicious score 0.9994

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.
  • 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.
  • 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)
  • PDF paints image(s) but contains no text operators info PDF_IMAGE_ONLY_LURE
    PDF has 1 image XObject(s) and the content stream contains no text-emitting operators (BT/ET, Tj, TJ, ', ") in either raw bytes or decompressed streams — this is the screenshot-as-PDF pattern used to bypass text-based scanners and to deliver instructions purely through rendered pixels. It is informational unless paired with invisible links or risky URI context.
  • 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 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
javascript_obj0099_000.js
ad4880b5db7323b44547334667156ea257f8fa558ebfab9cc08761f4e4237f8e
pdf-javascript-stream PDF /JS object 99 at offset 0x548D 8717 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 2 eval/decoder/string-building token(s). Carved artifact contains 9 long base64-like blob(s).
deobfuscated.js
3eda4f8cee21ebf719fb4059de5bd3274814abab03c224c517d75ccb5d3875b2
deobfuscated-js PDF JavaScript deobfuscation pass 39902 bytes
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact contains 4 eval/decoder/string-building token(s). Carved artifact contains 18 long base64-like blob(s).