PDF malware analysis — malicious · b09d929ad4bf9b39

MALICIOUS

PDF

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

MD5: c81a616d841ee42f3e0291d7dac1289d SHA-1: bb7b4e78cacd1099c73b73e163dfc90eb6ada3bc SHA-256: b09d929ad4bf9b39ef3907535d599d9872d2c98ecffbaf8cc2392fe8fb3d00ce

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 JavaScript stream utilizes `eval()` and `String.fromCharCode`, suggesting obfuscation and dynamic code execution. The ML classifier strongly flags this PDF as malicious. The primary intent appears to be downloading and executing a second-stage payload, as evidenced by the embedded JavaScript and its obfuscated nature. No specific family could be identified.

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` `d9328691619951de294a059d5fa44ca7a687a6078d7b3ade902d9522d6d1b6a7`	pdf-javascript-stream	PDF /JS object 1 at offset 0xA	886 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 5 eval/decoder/string-building token(s).

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