PDF malware analysis — malicious · f882b40b33b58aa5

MALICIOUS

PDF

15.9 KB

MD5: edfdf6914c7f1bbf3a54070b9f604897 SHA-1: 8dce845a68dc9d7fe8b217181baa0f3dd02bf2d7 SHA-256: f882b40b33b58aa5ef3abb707bb3e3bc77f25530567a6c278eb211dea70e72cd

76 Risk Score

Malware Insights

MITRE ATT&CK

T1059.001 JavaScript/JScript T1566.001 Spearphishing Attachment

The PDF file was flagged by a machine learning classifier as malicious and contains embedded JavaScript. The JavaScript stream, named 'javascript_obj0006_000.js', is heavily obfuscated, but heuristic analysis indicates the use of String.fromCharCode and ASCIIHexDecode filters, common techniques for hiding malicious code. The primary function of the script appears to be downloading and executing a second-stage payload, which is a common attack vector for PDF-based malware.

Machine Learning

Nyx PDF Classifier malicious score 0.9929

Heuristics 5

ASCIIHexDecode filter (with exploit indicators) medium PDF_FILTER_HEX

Hex-encoding filter present alongside exploit delivery indicators — often used to hide payload or shellcode bytes
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. (matched inside decoded stream)
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_obj0006_000.js` `262878d18538de4a46ebd88c55a96188ee752508d819c0760f8976fca6e42003`	pdf-javascript-stream	PDF /JS object 6 at offset 0x19C	17340 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact contains 1 eval/decoder/string-building token(s). Carved artifact contains 1 long base64-like blob(s).

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