PDF malware analysis — malicious · 7e1988d932ea9630

MALICIOUS

PDF

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

MD5: b6387d6bd4d00f4d2bc4db93da5be137 SHA-1: cfd31292285dd26fcb54e58b1ecbe06b1b7d4a9a SHA-256: 7e1988d932ea9630fffadd6c4d6ec946d7fb9a00801a1bdce8089ac99aa2c82a

94 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Phishing: Spearphishing Attachment T1027 Obfuscated Files or Information

The PDF file contains embedded JavaScript, identified by heuristics such as 'PDF_JAVASCRIPT' and 'PDF_JS'. A high-confidence heuristic 'PDF_METADATA_EVAL_STAGER' indicates that the JavaScript is used to decode and execute code from the PDF's metadata. The ML classifier also strongly flags this PDF as malicious. The presence of 'String.fromCharCode' suggests obfuscation techniques are employed within the JavaScript. The primary function appears to be a stager for executing further malicious actions, likely downloading and running a second-stage payload.

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` `d3b5631c2cc66f5bd9f3992bbbfae1693bace9fe0aa1a6f44cceaefbeee8e3de`	pdf-javascript-stream	PDF /JS object 1 at offset 0x6191	452 bytes

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