PDF malware analysis — malicious · da27fbcd9a9e2587

MALICIOUS

PDF

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

MD5: a86408d8ccca13581d0df463aadcfcfb SHA-1: c2d99b0cdca493c46c09a77945c6294a9f8add25 SHA-256: da27fbcd9a9e2587792ad40781752d08bbfdd40f94369901d3e8bcc7af31a540

94 Risk Score

Malware Insights

MITRE ATT&CK

T1566.002 Phishing: Spearphishing Attachment T1204.002 Malicious File Execution: Malicious Script

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_METADATA_EVAL_STAGER'. The 'ML_NYX_PDF_MALICIOUS' classifier strongly suggests malicious intent. The JavaScript is likely used as a stager to download and execute a second-stage payload. The use of String.fromCharCode further supports the obfuscation of JavaScript code.

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` `ec2cf94b77d7732d75ceb6cd680495dfb0f8fdd496f096558b978f013eba51d6`	pdf-javascript-stream	PDF /JS object 1 at offset 0x6280	540 bytes

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