PDF malware analysis — malicious · 44c37c05dd4032a7

MALICIOUS

PDF

16.2 KB

MD5: 35803da9044ced1466fc35a2ff873dfa SHA-1: 24beec0c54b9026cd52f1e6d36646da5a86a0f89 SHA-256: 44c37c05dd4032a700cb99c8c0079d4143b23fa4f27eb811a6208197bbf8b0ab

96 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 PowerShell

The PDF file contains embedded JavaScript, which is heavily obfuscated and utilizes `eval()` and `String.fromCharCode()`. The ML classifier strongly indicates maliciousness. The extracted JavaScript files, particularly `legacy_pdfkit_stage_000.js`, are likely responsible for downloading and executing a secondary payload, a common technique for initial access. The obfuscation and use of `eval` suggest an attempt to evade static analysis.

Machine Learning

Nyx PDF Classifier malicious score 0.9999

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. (matched inside decoded stream)
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 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`javascript_obj0004_000.js` `51de62b40d76a102a902461211a43b4990c8df5202a0013524aa4f4364b06eb5`	pdf-javascript-stream	PDF /JS object 4 at offset 0xE1	312 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 2 eval/decoder/string-building token(s).
`legacy_pdfkit_stage_000.js` `4220988f9ac6e3c69be15bcace2b9f4ddd2090ecd6a90bf2267bbf45960bb6e6`	deobfuscated-js	repeated-marker hex decoded JavaScript at offset 0x1B53	12493 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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