PDF malware analysis — malicious · b4aa65c37700afe3

MALICIOUS

PDF

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

MD5: 67703c11de78e08160391ea90dd3a689 SHA-1: 29749f0eae7fa3d173fa4c17b66533b9caaf5678 SHA-256: b4aa65c37700afe39f254af70d9128eca6a86ffe44378711a6527a4bc9016aa7

64 Risk Score

Malware Insights

MITRE ATT&CK

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

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_METADATA_EVAL_STAGER'. The 'String.fromCharCode' usage suggests obfuscation. The primary function of the embedded JavaScript appears to be a stager, likely intended to download and execute a second-stage payload. The file's metadata also contains JavaScript, further supporting its malicious intent.

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` `217c9701a4588c9356b02d81100a7e285a391b507afd8cfa82de2039356de65f`	pdf-javascript-stream	PDF /JS object 1 at offset 0x6369	518 bytes

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