PDF malware analysis — malicious · 22045aa66f76b760

MALICIOUS

PDF

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

MD5: e08a217c89bc22ed5b935267d1c77c53 SHA-1: 20d88ed93568f30c301954b9f0f767d272f037d1 SHA-256: 22045aa66f76b760d3b95c7a70a4e3c624940943fa13b0b2773ba28efa77e24c

98 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter: PowerShell T1204.002 Malicious File: User Execution: Malicious File

This PDF file contains embedded JavaScript, indicated by multiple heuristic firings including PDF_JAVASCRIPT, PDF_JS, and PDF_FROMCHARCODE. The high-severity PDF_EVAL firing suggests the JavaScript is being used to execute arbitrary code. The ML classifier also flagged this PDF as malicious with high confidence. The embedded JavaScript file, 'javascript_obj0001_000.js', is the primary artifact, and its obfuscated nature points towards an attempt to download and execute a second-stage payload. The authoring application 'String.fromCharCode' further supports the use of obfuscated JavaScript.

Machine Learning

Nyx PDF Classifier malicious score 1.0000

Heuristics 5

eval() call high PDF_EVAL

eval() found — commonly used for obfuscated exploit execution (matched inside decoded stream)
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.
Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE

One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0001_000.js` `6e37dfab9a290afadd0ff3661b7194602694237bbaa4fb22f2658cda3786d349`	pdf-javascript-stream	PDF /JS object 1 at offset 0xA	540 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).

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