PDF malware analysis — malicious · b57fb0c0160ab2c8

MALICIOUS

PDF

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

MD5: e99b195695591715e6a5d88a46ba3105 SHA-1: b9a8336b7c9026cd5e32d92ce35f6f7b3cec13a2 SHA-256: b57fb0c0160ab2c8c6cfc0b51db51dc92028ad20a7b7276e519565df1c5b314c

98 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, indicated by the PDF_JAVASCRIPT and PDF_JS heuristics. The JavaScript stream utilizes `eval()` and `String.fromCharCode`, suggesting obfuscation and dynamic code execution. The ML classifier strongly flags this PDF as malicious. The primary attack vector appears to be the execution of obfuscated JavaScript from within the PDF, likely to download and execute a secondary 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` `95f1fb16d40af8f96c530d6a670ed5586851d1d1260ceeaee6e179c195d635ce`	pdf-javascript-stream	PDF /JS object 1 at offset 0xA	1049 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).

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