PDF malware analysis — malicious · af52d8e2bd9198f8

MALICIOUS

PDF

23.6 KB

MD5: 9e106c129448288f646738c5d41d8c8c SHA-1: 4a5f7ec7d9dc00a47334bcb71d95c742550a6936 SHA-256: af52d8e2bd9198f8f189d088c9a7c3efdc2457b40560628d1fae63ed7ef067bf

120 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

This PDF sample exhibits multiple critical heuristic firings related to JavaScript exploits, including the use of String.fromCharCode for obfuscation. The embedded JavaScript, both original and deobfuscated, is heavily obfuscated, but the presence of 'vz='c'; a='...' indicates it's designed to reconstruct and execute code. The ML classifier strongly flags this as malicious. Given the PDF structure and the JavaScript exploit cluster, the likely attack pattern involves exploiting a PDF vulnerability to run obfuscated JavaScript, which in turn is expected to download and execute a secondary payload.

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.

Filename	Kind	Source	Size
`javascript_obj0099_000.js` `ce82b656603c3f58a4615ece061158c4c9af74d78ae73ceca9bac097769d6094`	pdf-javascript-stream	PDF /JS object 99 at offset 0x548D	8657 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` `a67bf23557bf1980b589d50cccb66df5ef415f42fd103b6dbee8dbdf97dec273`	deobfuscated-js	PDF JavaScript deobfuscation pass	103223 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).

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