PDF malware analysis — malicious · d374fbef9c7109b9

MALICIOUS

PDF

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

MD5: 9666f7e09eccd2865eb7a0770bfd5f81 SHA-1: 5e1b3f656905d4b89459945ea343d2d4fa7ff263 SHA-256: d374fbef9c7109b985509cb5c637a6b072fccaa2168d36d67bfe0a53112cee6a

64 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 file contains embedded JavaScript, identified by the 'PDF_JAVASCRIPT' and 'PDF_JS' heuristics. The 'PDF_METADATA_EVAL_STAGER' heuristic specifically indicates that the JavaScript is used to decode and execute a stager from the PDF's metadata. The use of 'String.fromCharCode' further supports the obfuscation technique employed by the stager. While the exact payload is not discernible from the static analysis, the stager's purpose is to download and execute a second-stage payload. The document body text is minimal and does not provide further context.

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` `fe2186fae1c5ced4e26538e01e042a22f8b94b11a4b00a24d4dca238e7014d67`	pdf-javascript-stream	PDF /JS object 1 at offset 0x6241	527 bytes

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