PDF malware analysis — malicious · fb3bb7d5b966b2ad

MALICIOUS

PDF

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

MD5: 024a1717cadfbb0ef96a35b97fdf8125 SHA-1: 59a0f5d50d05afc152989ee1d6dbc35b7c18ada8 SHA-256: fb3bb7d5b966b2ad10fcd9714d9eeb1f1df1feb17890f415e0794a977764494d

94 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

The PDF file contains embedded JavaScript, identified by heuristics like 'PDF_JAVASCRIPT' and 'PDF_JS'. The 'PDF_METADATA_EVAL_STAGER' heuristic indicates that JavaScript within the PDF's metadata is used to decode and execute code. The ML classifier strongly flags this PDF as malicious. The presence of 'String.fromCharCode' suggests obfuscation techniques are employed within the JavaScript. The primary intent appears to be the execution of a stager that likely downloads and runs a second-stage payload.

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` `4206ef7f18b89cd9c7feaf9ed4b8ef8d4e245c6773f335f5674092530eb7fc71`	pdf-javascript-stream	PDF /JS object 1 at offset 0x623A	516 bytes

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