PDF malware analysis — malicious · c7c8aead600c9220

MALICIOUS

PDF

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

MD5: 9a6aa919e65ee3ff191ec6baad3dbdc5 SHA-1: d2a093cc8f749c3f24aabdf4e93b961819aebfee SHA-256: c7c8aead600c92200d41bda45dc70dca7822a937b8ff6282031f9148bd63efed

94 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter: PowerShell T1204.002 Malicious File: User Execution: Malicious File

The PDF contains embedded JavaScript, flagged by multiple heuristics including a high-severity 'PDF_METADATA_EVAL_STAGER'. The JavaScript is obfuscated using String.fromCharCode, a common technique for evading static analysis. The ML classifier strongly indicates maliciousness. The primary attack pattern involves leveraging PDF's JavaScript capabilities to execute arbitrary code, likely for further payload 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` `817ccc1eb8a703f8bc859833a5f4ce2956a4b74dc983106f64d1129435d6327b`	pdf-javascript-stream	PDF /JS object 1 at offset 0x6186	453 bytes

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