PDF malware analysis — malicious · f165c1cb9953e78a

MALICIOUS

PDF

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

MD5: 0729136306c04bd61fc93fd16dea2977 SHA-1: 335ccbcb078b615cbefd6890fe322b6fb9e7e193 SHA-256: f165c1cb9953e78aa7968f68d155f179b46b62b8897d2f2f1c63ebe88a6ee3e7

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 file contains embedded JavaScript, indicated by the PDF_JAVASCRIPT and PDF_JS heuristics. The presence of PDF_EVAL and the ML classifier's high confidence score strongly suggest malicious intent. The JavaScript stream, named javascript_obj0001_000.js, is likely responsible for executing the malicious payload, although its specific actions are not detailed in the provided evidence. The use of String.fromCharCode further points to obfuscation techniques common in malicious scripts.

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` `3f1ae27c0d59b4fa890db34d9c9c81bb722c414dc3fe44d8a874632dc08d1258`	pdf-javascript-stream	PDF /JS object 1 at offset 0xA	957 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).

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