PDF malware analysis — malicious · 1fb6177930f57278

MALICIOUS

PDF

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

MD5: a3e5297e9935d7561ceeef168fffc5d4 SHA-1: 889a8dcd30bbdf14890d791423a5b0d4a1efc71f SHA-256: 1fb6177930f57278dc70c0c3dfe6b05154381efec1b8af7102e27d0f9bb464cb

94 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF file contains embedded JavaScript, triggered via metadata, which is a common technique for initial execution. The heuristic 'PDF_METADATA_EVAL_STAGER' strongly suggests the JavaScript is used to decode and execute further malicious code. The presence of 'String.fromCharCode' in the document body and heuristics indicates obfuscation techniques are employed. The ML classifier's high score further supports the malicious nature of the 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` `4cf9f30b3496fe3b0eefcbec5a2890a4b6691dbb763db714bf6a1fe5427ac8c4`	pdf-javascript-stream	PDF /JS object 1 at offset 0x627F	449 bytes

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