PDF malware analysis — malicious · d6d1559b9348bfc8

MALICIOUS

PDF

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

MD5: bfbdf1d8e9e6792f6bfb8e9e41a6aa9d SHA-1: a0aafb1e4069673a99042cedfc547287f7cc270e SHA-256: d6d1559b9348bfc8a0f5850060d43e8101a9baf4b004b26ae8fbdf49c7f55d2e

94 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

This PDF file was flagged as malicious by an ML classifier and exhibits high-confidence heuristic firings for a JavaScript eval stager within its metadata. The embedded JavaScript, likely constructed using String.fromCharCode, is designed to execute arbitrary code. This pattern suggests the document acts as a dropper, initiating a download and execution chain for further malicious activity.

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` `5304dc2c778670a09bd477bb514a67cd29471f5a05f99bc3c06e5edf2c7f3867`	pdf-javascript-stream	PDF /JS object 1 at offset 0x61D4	456 bytes

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