PDF malware analysis — malicious · d8fb77648124d1b8

MALICIOUS

PDF

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

MD5: 09aad2867dc3f8b0276a3aa526ee29ed SHA-1: 08edb5d500f1080ca83c4822995d2109d2853643 SHA-256: d8fb77648124d1b8ecce78fc3138c417f188b44f76f12bfb65db778bae8c515f

96 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter: PowerShell T1059.003 Command and Scripting Interpreter: Windows Command Shell T1059.007 Command and Scripting Interpreter: JavaScript/TypeScript

The PDF contains embedded JavaScript, flagged by multiple heuristics including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_EVAL'. The ML classifier also strongly indicates maliciousness. The JavaScript stream, named 'javascript_obj0001_000.js', is obfuscated and likely responsible for downloading and executing a second-stage payload. The use of String.fromCharCode and eval() within the JavaScript points to dynamic code execution.

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` `7ea88e82594fce1fc5f8418f04d721e2646100634f90e1b06b58bccd00ea0c47`	pdf-javascript-stream	PDF /JS object 1 at offset 0xA	516 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 6 eval/decoder/string-building token(s).

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