PDF malware analysis — malicious · 58015ab4011151c6

MALICIOUS

PDF

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

MD5: b16c900c739b039f78f4739a4f9ba63c SHA-1: 7872e4d0d627ff3753e3027a4e5baaac0fa55bb1 SHA-256: 58015ab4011151c6ffd686aae5eafea6d65119c0047e3c8288b7a37d84afc868

94 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter: PowerShell T1059.003 Command and Scripting Interpreter: Windows Command Shell T1059.007 Command and Scripting Interpreter: JavaScript/TypeScript

The PDF contains JavaScript within its metadata, which is used as a stager to decode and execute a malicious payload. The use of String.fromCharCode and PDF metadata JavaScript eval stager heuristics indicates a deliberate attempt to obfuscate the initial execution. The embedded JavaScript object, javascript_obj0001_000.js, is the primary artifact responsible for this behavior.

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` `58359dff6e31e9a2431e93a573badfb4a7b7d0dc062e3baecff693da1eda92df`	pdf-javascript-stream	PDF /JS object 1 at offset 0x62B0	515 bytes

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