PDF malware analysis — malicious · 825bb9d9cd02114e

MALICIOUS

PDF

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

MD5: cf7d4fb25333b6fbea9a8b5d979da603 SHA-1: 5568b0b0c1a229ca42f32101f94956d75b0339ac SHA-256: 825bb9d9cd02114e2d8fa57a421dd0c57738efac566d879e5926f46e54a82887

96 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 Command and Scripting Interpreter: PowerShell T1204.002 Malicious File: Malicious File

The PDF file contains embedded JavaScript, indicated by multiple heuristic firings including 'PDF_JAVASCRIPT', 'PDF_JS', and 'PDF_EVAL'. The JavaScript stream, named 'javascript_obj0001_000.js', is highly suspicious and likely responsible for executing the malicious payload. The ML classifier also strongly flagged this PDF as malicious. The use of String.fromCharCode and eval() suggests obfuscation to hide the script's true intent, which is presumed to be downloading and executing 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` `91a5a35f613342140f70fc2966776a71b6817b9d6556cb6b1284607ee67769a3`	pdf-javascript-stream	PDF /JS object 1 at offset 0xA	523 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 6 eval/decoder/string-building token(s).

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