PDF malware analysis — malicious · b0603f8c56e364d5

MALICIOUS

PDF

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

MD5: a43df12d5e328581c6dacdc70e17b1f2 SHA-1: e786a3fc2fc5384f70d8be3d4c9fd4cf55d50358 SHA-256: b0603f8c56e364d5c7cfddea0484cbe403f307384bc0c310eba1e3e21cd5d9e5

94 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF file contains embedded JavaScript, identified by heuristics such as '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 further code. The presence of 'String.fromCharCode' suggests obfuscation techniques are employed to hide the malicious payload. While the exact payload is not visible, the stager pattern strongly implies the download and execution of a second-stage malicious file.

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` `b3b668e526239fc500886aafc9057348ecc49e114fcfdb421b356254d127a3d4`	pdf-javascript-stream	PDF /JS object 1 at offset 0x629C	530 bytes

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