PDF malware analysis — malicious · a4a3ac35477b9b8d

MALICIOUS

PDF

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

MD5: b49e901bc744ff0c01ec9cd714193513 SHA-1: 58fb36cf5ac368d88f5bb33e25b7961a53d0e0f8 SHA-256: a4a3ac35477b9b8db8a44493f4e045430042e2d55c15667cfb00fd39e9680159

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 JavaScript execution within its metadata. The embedded JavaScript stream, named 'javascript_obj0001_000.js', is likely responsible for downloading and executing a second-stage payload. The use of String.fromCharCode further suggests obfuscation techniques common in malware delivery.

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` `5c76bcccd06337fb4b3613f01ee13908033db721edf16a9ec0279e8e996a10b9`	pdf-javascript-stream	PDF /JS object 1 at offset 0x629B	522 bytes

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