PDF malware analysis — malicious · d12b464a5c4caaa0

MALICIOUS

PDF

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

MD5: b2bc01cf489e93dd63b094a0bcf0b243 SHA-1: 1505a095c2344d6fd132b3374e7fa73045de46a6 SHA-256: d12b464a5c4caaa0b22506ac91f7acb691c8c51335ab0c42e8f978808a1cd11d

94 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell T1204.002 Malicious File

The PDF file contains embedded JavaScript, identified by heuristics like PDF_JAVASCRIPT and PDF_JS. The high-confidence heuristic PDF_METADATA_EVAL_STAGER indicates that JavaScript within the PDF's metadata is used as a stager. This stager likely decodes and executes further malicious code, as suggested by the ML classifier's high confidence. The presence of 'String.fromCharCode' in both the metadata and the document body further supports the use of obfuscated JavaScript for payload delivery. No specific family could be identified.

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` `7551987e5dfc3b6b29bd7b42a4608401b61ccfcfd78f3a0e8494495639aba2f5`	pdf-javascript-stream	PDF /JS object 1 at offset 0x627C	534 bytes

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