PDF malware analysis — malicious · 6b1cfdc4ad825986

MALICIOUS

PDF

20.6 KB

MD5: f35ac14c0a141b66964ff278a3be62da SHA-1: b1d5fc8581c8083b75545341409ce4ffa75d650f SHA-256: 6b1cfdc4ad825986af2452e2d8280e5e3c3858c27e788eb81125113a45ac6e81

120 Risk Score

Malware Insights

MITRE ATT&CK

T1059.007 JavaScript T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_JS_EXPLOIT_CLUSTER'. The JavaScript stream, named 'javascript_obj0099_000.js', is heavily obfuscated but its presence and the exploit cluster signal suggest it is designed to execute malicious code. The ML classifier also strongly flagged this PDF as malicious. The likely intent is to exploit a vulnerability to download and execute a secondary payload, consistent with a spearphishing attachment.

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#

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0099_000.js` `64706c0746825037f9775ac5cbe6914293b7e41d75ce6e55cb4658f3d11b8885`	pdf-javascript-stream	PDF /JS object 99 at offset 0x479A	20240 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).

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