PDF malware analysis — malicious · 650bb79e537e47e8

MALICIOUS

PDF

20.5 KB

MD5: 6661cb07abd87e55e02b0703b83e68a6 SHA-1: 16ccda69a238063984afdda0f88ec8af9d134120 SHA-256: 650bb79e537e47e83d8c035ae8a6643d5524ca26372d13f0b96e4ca7d77d8ca6

120 Risk Score

Malware Insights

MITRE ATT&CK

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

The PDF contains embedded JavaScript, flagged by multiple heuristics as a critical exploit cluster. The JavaScript stream, named 'javascript_obj0099_000.js', is heavily obfuscated but its presence and the exploit cluster firing strongly suggest it's designed to download and execute a second-stage payload. The ML classifier also strongly indicates maliciousness.

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` `691f4f3e500bdb2f23fe4b7c28bc3f78e2fb821e793c2e1e0839e6378d3fcfd1`	pdf-javascript-stream	PDF /JS object 99 at offset 0x479A	19790 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s).

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