PDF malware analysis — malicious · 43caf784e4926f28

MALICIOUS

PDF

26.1 KB Created: 2011-72-51 03:25:00 Authoring application: String.fromCharCode

MD5: aeadf336a8ded5704c8c9705af434f7f SHA-1: 1cfac2c4c5d67d81004ab1e357672fbf0347af33 SHA-256: 43caf784e4926f2880244841743ebad8d9d7da7b936fb2ac0461cc1ce219d863

96 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

This PDF file contains embedded JavaScript, indicated by multiple heuristic firings including PDF_JAVASCRIPT, PDF_JS, and PDF_FROMCHARCODE. The presence of a high-confidence ML classifier hit (ML_NYX_PDF_MALICIOUS) and a high-severity PDF_EVAL heuristic firing strongly suggests malicious intent. The JavaScript is obfuscated and uses String.fromCharCode, a common technique to hide malicious code. The primary function of the script appears to be executing arbitrary code via eval(), which is likely used to download and run a secondary payload. No specific family could be identified.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 5

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.
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.
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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0001_000.js` `465d8f162bd64a7e80a7b57d3db5795dd705697e77831460951b876760827674`	pdf-javascript-stream	PDF /JS object 1 at offset 0xA	886 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).

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