PDF malware analysis — malicious · 529bda17e4f7acda

MALICIOUS

PDF

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

MD5: fe449dd34ed0d9af6825f10594818dd9 SHA-1: a2396c2c7e58eba2ac57470c31ff4054bc1c883d SHA-256: 529bda17e4f7acda30e090445a7d8540f3cdcc4755b8deb9f78a78cca59cb2c4

64 Risk Score

Malware Insights

MITRE ATT&CK

T1204.002 Malicious File: Malicious File

The PDF sample contains embedded JavaScript, identified by the 'PDF_JAVASCRIPT' and 'PDF_JS' heuristics. The 'PDF_METADATA_EVAL_STAGER' heuristic indicates that this JavaScript is used to decode and execute further code, likely from the PDF's metadata. The 'String.fromCharCode' usage further supports obfuscated JavaScript execution. While no specific URLs or further payloads were extracted, the pattern strongly suggests a downloader or stager designed to fetch and execute a malicious payload. The file's metadata also indicates it was authored using 'String.fromCharCode', aligning with the obfuscation techniques observed.

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` `68d8f7b48f721f0e14e65028f692f5e7630075ba338a5ce4774a256424d4b40e`	pdf-javascript-stream	PDF /JS object 1 at offset 0x621B	535 bytes

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