PDF malware analysis — malicious · f8be163c5d9d8b3f

MALICIOUS

PDF

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

MD5: 114a7892e5c11ea699742cc390f5ecc3 SHA-1: 443278c4e9373ed9a28f8ad68acd1ca9373ce54d SHA-256: f8be163c5d9d8b3f85e6b49dd8da41212fede3f611ec8bd1dcedaeb40444facf

96 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter: PowerShell

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings including PDF_JAVASCRIPT and PDF_JS. The JavaScript stream utilizes `eval()` and `String.fromCharCode` for obfuscation, a common technique for malicious scripts. The ML classifier strongly flags this PDF as malicious. The primary intent appears to be the execution of obfuscated JavaScript, likely to download and execute a second-stage payload.

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` `2bc23ddd657f7e1d01616feeee525226b7a5055590cae71897a6760801a77246`	pdf-javascript-stream	PDF /JS object 1 at offset 0xA	522 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 6 eval/decoder/string-building token(s).

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