PDF malware analysis — malicious · ac4ecfd34b221534

MALICIOUS

PDF

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

MD5: 4e530a85b551f7d69930fb9889fe2246 SHA-1: cba6e830a52f99ed240ef9badf5d261d027afbf8 SHA-256: ac4ecfd34b221534f35f294dda3556949266200095cf3ecd0b528db7456f1572

64 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter: PowerShell

The PDF file contains embedded JavaScript within its metadata, identified by the 'PDF_METADATA_EVAL_STAGER' heuristic. This JavaScript, likely obfuscated using String.fromCharCode, is designed to decode and execute a malicious payload. The presence of JavaScript actions and streams further supports this. The primary function appears to be the execution of a second-stage payload, though the exact nature is not fully discernible from the provided evidence.

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` `4afdf9ac7a04f800f0fa0824a5e1fd87b6dfed5f17ddf4bd759be460864aa648`	pdf-javascript-stream	PDF /JS object 1 at offset 0x6221	452 bytes

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