PDF malware analysis — malicious · c9c91e6101afa565

MALICIOUS

PDF

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

MD5: b5c780e42a155276d13a398c3d66d070 SHA-1: e0df0b4b1530a4b7a1da61fd64fef987c9634cdf SHA-256: c9c91e6101afa5656e364f1a654e1f77f95e4c8839b921a5ac39fd25848a381e

94 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

This PDF sample contains embedded JavaScript, flagged by multiple heuristics including 'PDF_METADATA_EVAL_STAGER'. The JavaScript stream, named 'javascript_obj0001_000.js', is likely responsible for downloading and executing a second-stage payload. The use of String.fromCharCode further indicates obfuscation techniques common in malware delivery. The ML classifier strongly supports the malicious verdict.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 4

PDF metadata JavaScript eval stager high PDF_METADATA_EVAL_STAGER

PDF JavaScript reads document metadata fields such as title, subject, or producer, decodes character data with parseInt/String.fromCharCode style helpers, and evals the recovered stage. This is a high-signal exploit-kit staging pattern.
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.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0001_000.js` `4414981cba388d8b81d94dc13c2b9a966cdeeaa4058ecf030fafecb167f0bff0`	pdf-javascript-stream	PDF /JS object 1 at offset 0x6212	456 bytes

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